preprints refereed journals refereed conference proceedings theses

preprints

2023

arXiv
Supersymmetric Casimir energy on $\mathcal{N}=1$ conformal supergravity backgrounds

Pantelis Panopoulos, and Ioannis Papadimitriou

2023

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We provide a first principles derivation of the supersymmetric Casimir energy of $\mathcal{N}=1$ SCFTs in four dimensions using the supercharge algebra on general conformal supergravity backgrounds that admit Killing spinors. The superconformal Ward identities imply that there exists a continuous family of conserved R-currents on supersymmetric backgrounds, as well as a continuous family of conserved currents for each conformal Killing vector. These continuous families interpolate between the consistent and covariant R-current and energy-momentum tensor. The resulting Casimir energy, therefore, depends on two continuous parameters corresponding to the choice of conserved currents used to define the energy and R-charge. This ambiguity is in addition to any possible scheme dependence due to local terms in the effective action. As an application, we evaluate the general expression for the supersymmetric Casimir energy we obtain on a family of backgrounds with the cylinder topology R×S3R×S3 and admitting two supercharges of opposite R-charge. Our result is a direct consequence of the supersymmetry algebra, yet it resembles more known expressions for the non-supersymmetric Casimir energy on such backgrounds and differs from the supersymmetric Casimir energy obtained from the zero temperature limit of supersymmetric partition functions. We defer a thorough analysis of the relation between these results to future work.
@article{Panopoulos:2023cdg, category = {preprint}, title = {Supersymmetric Casimir energy on $\mathcal{N}=1$ conformal supergravity backgrounds}, author = {Panopoulos, Pantelis and Papadimitriou, Ioannis}, arxiv = {2312.17740}, archiveprefix = {arXiv}, primaryclass = {hep-th}, year = {2023}, dimensions = {true}, }

refereed journals

2022

JHEP
Black hole superpotential as a unifying entropy function and BPS thermodynamics

Praxitelis Ntokos, and Ioannis Papadimitriou

JHEP, 2022

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We develop an effective superpotential formalism for the SU(2)×U(1) invariant sector of $\mathcal{N} = 2$ gauged supergravity in five dimensions with a U(1)$^3$ Fayet-Iliopoulos gauging, and determine the exact superpotential that describes all 1/4 BPS solutions in this sector. This includes the Gutowski-Reall black holes, but also a much broader class of solutions with a squashed $S^3$, magnetic flux and vector multiplet sources, as well as complex Euclidean BPS saddles. Some of these solutions are known only numerically, but the exact superpotential allows us to analytically evaluate the on-shell action, holographic one-point functions and conserved charges of all BPS solutions and to study their thermodynamics. In particular, by examining the supersymmetry Ward identities we show that solutions with supersymmetric vector multiplet sources break supersymmetry spontaneously. We also demonstrate the first law for black holes in the SU(2)×U(1) invariant sector and show that the conserved charges of supersymmetric solutions satisfy the generalized BPS relation derived in arXiv:1703.04299, which includes the supersymmetric Casimir energy as a consequence of the anomalous supersymmetry transformation of the $\mathcal{N} = 1$ supercurrent at the boundary. Finally, we show that the effective superpotential provides a unifying entropy extremization principle, reproducing Sen’s entropy function for near extremal black holes and the Hosseini-Hristov-Zaffaroni functional for complex Euclidean BPS saddles.
@article{Ntokos:2021duk, category = {article}, title = {Black hole superpotential as a unifying entropy function and BPS thermodynamics}, author = {Ntokos, Praxitelis and Papadimitriou, Ioannis}, arxiv = {2112.05954}, archiveprefix = {arXiv}, primaryclass = {hep-th}, journal = {JHEP}, volume = {03}, pages = {058}, year = {2022}, publisher = {Springer}, doi = {10.1007/JHEP03(2022)058}, dimensions = {true}, }
PRD
Anomalies and supersymmetry

Ruben Minasian, Ioannis Papadimitriou, and Piljin Yi

Phys. Rev. D, 2022

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We revisit quantum field theory anomalies, emphasizing the interplay with diffeomorphisms and supersymmetry. The Ward identities of the latter induce Noether currents of all continuous symmetries, and we point out how these consistent currents are replaced by their covariant form through the appearance of the Bardeen-Zumino currents, which play a central role in our study. For supersymmetry Ward identities, two systematic methods for solving the Wess-Zumino consistency conditions are discussed: anomaly inflow and anomaly descent. The simplest inflows are from supersymmetric Chern-Simons actions in one dimension higher, which are used to supersymmetrize flavor anomalies in $d=4$ and, for $d=2$ $\mathcal{N} = (p,q)$, flavor anomalies with $p,q≤3$ and Lorentz-Weyl anomalies with $p,q≤6$. Finally, we extend the BRST algebra and the subsequent descent, a necessity for the diffeomorphism anomaly in retrospect. The same modification computes the supersymmetrized anomalies, and determines the above Chern-Simons actions when these exist.
@article{Minasian:2021png, category = {article}, author = {Minasian, Ruben and Papadimitriou, Ioannis and Yi, Piljin}, title = {Anomalies and supersymmetry}, arxiv = {2104.13391}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P21011}, journal = {Phys. Rev. D}, volume = {105}, number = {6}, pages = {065005}, year = {2022}, publisher = {American Physical Society}, doi = {10.1103/PhysRevD.105.065005}, dimensions = {true}, }

2021

JHEP
AdS$_{3}$ gravity and the complex SYK models

Pankaj Chaturvedi, Ioannis Papadimitriou, Wei Song, and Boyang Yu

JHEP, 2021

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We provide a non conformal generalization of the Compère-Song-Strominger (CSS) boundary conditions for AdS3 gravity that breaks the $\hat{u}(1)$ Kac-Moody-Virasoro symmetry to two $u(1)$s. The holographic dual specified by the new boundary conditions can be understood as an irrelevant deformation of a warped conformal field theory (WCFT). Upon consistent reduction to two dimensions, AdS$_3$ gravity results in a deformed Jackiw-Teitelboim dilaton gravity model coupled to a Maxwell field. We show that near extremality the boundary conditions inherited from generalized CSS boundary conditions in three dimensions give rise to an effective action exhibiting the same symmetry breaking pattern as the complex Sachdev-Ye-Kitaev models. Besides the Schwarzian term reflecting the breaking of conformal symmetry, the effective action contains an additional term that captures the breaking of the $\hat{u}(1)$ Kac-Moody symmetry.
@article{Chaturvedi:2020jyy, category = {article}, author = {Chaturvedi, Pankaj and Papadimitriou, Ioannis and Song, Wei and Yu, Boyang}, title = {AdS$_{3}$ gravity and the complex SYK models}, arxiv = {2011.10001}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P20068}, journal = {JHEP}, volume = {05}, pages = {142}, year = {2021}, doi = {10.1007/JHEP05(2021)142}, dimensions = {true}, }

2020

JHEP
Supersymmetry anomaly in the superconformal Wess-Zumino model

Georgios Katsianis, Ioannis Papadimitriou, Kostas Skenderis, and Marika Taylor

JHEP, 2020

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We present a comprehensive analysis of supersymmetry anomalies in the free and massless Wess-Zumino (WZ) model in perturbation theory. At the classical level the model possesses $\mathcal{N} = 1$ superconformal symmetry, which is partially broken by quantum anomalies. The form of the anomalies and the part of the symmetry they break depend on the multiplet of conserved currents used. It was previously shown that the R-symmetry anomaly of the conformal current multiplet induces an anomaly in Q-supersymmetry, which appears first in 4-point functions. Here we confirm this result by an explicit 1-loop computation using a supersymmetric Pauli-Villars regulator. The conformal current multiplet does not exist in the regulated theory because the regulator breaks conformal invariance, R-symmetry and S-supersymmetry explicitly. The minimal massive multiplet is the Ferrara-Zumino (FZ) one and the supersymmetry preserved by the regulator is a specific field dependent combination of Q- and S- supersymmetry of the conformal multiplet. While this supersymmetry is non anomalous, conformal invariance, R-symmetry and the original Q- and S-supersymmetries are explicitly broken by finite contact terms, both in the regulated and renormalized theories. A conformal current multiplet does exist for the renormalized theory and may be obtained from the FZ multiplet by a set of finite local counterterms that eliminate the explicit symmetry breaking, thus restoring superconformal invariance up to anomalies. However, this necessarily renders both Q- and S-supersymmetries anomalous, as is manifest starting at 4-point functions of conformal multiplet currents. The paper contains a detailed discussion of a number of issues and subtleties related to Ward identities that may be useful in a wider context.
@article{Katsianis:2020hzd, category = {article}, author = {Katsianis, Georgios and Papadimitriou, Ioannis and Skenderis, Kostas and Taylor, Marika}, title = {Supersymmetry anomaly in the superconformal Wess-Zumino model}, arxiv = {2011.09506}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P20067}, journal = {JHEP}, volume = {21}, pages = {209}, year = {2020}, doi = {10.1007/JHEP02(2021)209}, dimensions = {true}, }
JHEP
Counterterms, Kounterterms, and the variational problem in AdS gravity

Giorgos Anastasiou, Olivera Miskovic, Rodrigo Olea, and Ioannis Papadimitriou

JHEP, 2020

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We show that the Kounterterms for pure AdS gravity in arbitrary even dimensions coincide with the boundary counterterms obtained through holographic renormalization if and only if the boundary Weyl tensor vanishes. In particular, the Kounterterms lead to a well posed variational problem for generic asymptotically locally AdS manifolds only in four dimensions. We determine the exact form of the counterterms for conformally flat boundaries and demonstrate that, in even dimensions, the Kounterterms take exactly the same form. This agreement can be understood as a consequence of Anderson's theorem for the renormalized volume of conformally compact Einstein 4-manifolds and its higher dimensional generalizations by Albin and Chang, Qing and Yang. For odd dimensional asymptotically locally AdS manifolds with a conformally flat boundary, the Kounterterms coincide with the boundary counterterms except for the logarithmic divergence associated with the holographic conformal anomaly, and finite local terms.
@article{Anastasiou:2020zwc, category = {article}, author = {Anastasiou, Giorgos and Miskovic, Olivera and Olea, Rodrigo and Papadimitriou, Ioannis}, title = {Counterterms, Kounterterms, and the variational problem in AdS gravity}, arxiv = {2003.06425}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P20010}, journal = {JHEP}, volume = {08}, pages = {061}, year = {2020}, doi = {10.1007/JHEP08(2020)061}, dimensions = {true}, }

2019

JHEP
Supersymmetry anomalies in new minimal supergravity

Ioannis Papadimitriou

JHEP, 2019

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We determine the general structure of quantum anomalies for the R-multiplet of four dimensional $\mathcal{N} = 1$ supersymmetric quantum field theories in the presence of background fields for an arbitrary number of Abelian flavor multiplets. By solving the Wess-Zumino consistency conditions for off-shell new minimal supergravity in four dimensions with an arbitrary number of Abelian vector multiplets, we compute the anomaly in the conservation of the supercurrent to leading non trivial order in the gravitino and vector multiplet fermions. We find that both R-symmetry and flavor anomalies necessarily lead to a supersymmetry anomaly, thus generalizing our earlier results to non superconformal theories with Abelian flavor symmetries. The anomaly in the conservation of the supercurrent leads to an anomalous transformation for the supercurrent under rigid supersymmetry on bosonic backgrounds that admit new minimal Killing spinors. The resulting deformation of the supersymmetry algebra has implications for supersymmetric localization computations on such backgrounds.
@article{Papadimitriou:2019yug, category = {article}, author = {Papadimitriou, Ioannis}, title = {Supersymmetry anomalies in new minimal supergravity}, arxiv = {1904.00347}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P19022}, journal = {JHEP}, volume = {09}, pages = {039}, year = {2019}, doi = {10.1007/JHEP09(2019)039}, dimensions = {true}, }
PRL
Anomalous Supersymmetry

George Katsianis, Ioannis Papadimitriou, Kostas Skenderis, and Marika Taylor

Phys. Rev. Lett., 2019

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We show that supersymmetry is anomalous in $\mathcal{N} = 1$ superconformal quantum field theories (SCFTs) with an anomalous R-symmetry. This anomaly was originally found in holographic SCFTs at strong coupling. Here we show that this anomaly is present in general and demonstrate it for the massless superconformal Wess-Zumino model via a one loop computation. The anomaly appears first in four-point functions of two supercurrents with either two R-currents or with an R-current and an energy momentum tensor. In fact, the Wess-Zumino consistency conditions together with the standard R-symmetry anomaly imply the existence of the anomaly. We outline the implications of this anomaly.
@article{Katsianis:2019hhg, category = {article}, author = {Katsianis, George and Papadimitriou, Ioannis and Skenderis, Kostas and Taylor, Marika}, title = {Anomalous Supersymmetry}, arxiv = {1902.06715}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P19008}, journal = {Phys. Rev. Lett.}, volume = {122}, number = {23}, pages = {231602}, year = {2019}, doi = {10.1103/PhysRevLett.122.231602}, dimensions = {true}, }
JHEP
Supersymmetry anomalies in $\mathcal{N}=1$ conformal supergravity

Ioannis Papadimitriou

JHEP, 2019

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We solve the Wess-Zumino consistency conditions of $\mathcal{N} = 1$ off-shell conformal supergravity in four dimensions and determine the general form of the superconformal anomalies for arbitrary a and c anomaly coefficients to leading non trivial order in the gravitino. Besides the well known Weyl and R-symmetry anomalies, we compute explicitly the fermionic Q- and S-supersymmetry anomalies. In particular, we show that Q-supersymmetry is anomalous if and only if R-symmetry is anomalous. The Q- and S-supersymmetry anomalies give rise to an anomalous supersymmetry transformation for the supercurrent on curved backgrounds admitting Killing spinors, resulting in a deformed rigid supersymmetry algebra. Our results may have implications for supersymmetric localization and supersymmetry phenomenology. Analogous results are expected to hold in dimensions two and six and for other supergravity theories. The present analysis of the Wess-Zumino consistency conditions reproduces the holographic result of arXiv:1703.04299 and generalizes it to arbitrary a and c anomaly coefficients.
@article{Papadimitriou:2019gel, category = {article}, author = {Papadimitriou, Ioannis}, title = {Supersymmetry anomalies in $\mathcal{N}=1$ conformal supergravity}, arxiv = {1902.06717}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P19007}, journal = {JHEP}, volume = {04}, pages = {040}, year = {2019}, doi = {10.1007/JHEP04(2019)040}, dimensions = {true}, }

2018

JHEP
5D rotating black holes and the nAdS$_{2}$/nCFT$_{1}$ correspondence

Alejandra Castro, Finn Larsen, and Ioannis Papadimitriou

JHEP, 2018

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We study rotating black holes in five dimensions using the nAdS$_2$/nCFT$_1$ correspondence. A consistent truncation of pure Einstein gravity (with a cosmological constant) in five dimensions to two dimensions gives a generalization of the Jackiw-Teitelboim theory that has two scalar fields: a dilaton and a squashing parameter that breaks spherical symmetry. The interplay between these two scalar fields is non trivial and leads to interesting new features. We study the holographic description of this theory and apply the results to the thermodynamics of the rotating black hole from a two dimensional point of view. This setup challenges notions of universality that have been advanced based on simpler models: we find that the mass gap of Kerr-AdS$_5$ corresponds to an undetermined effective coupling in the nAdS$_2$/nCFT$_1$ theory which depends on ultraviolet data.
@article{Castro:2018ffi, category = {article}, author = {Castro, Alejandra and Larsen, Finn and Papadimitriou, Ioannis}, title = {5D rotating black holes and the nAdS$_{2}$/nCFT$_{1}$ correspondence}, arxiv = {1807.06988}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P18074}, journal = {JHEP}, volume = {10}, pages = {042}, year = {2018}, doi = {10.1007/JHEP10(2018)042}, dimensions = {true}, }
JHEP
Thermoelectric DC conductivities in hyperscaling violating Lifshitz theories

Sera Cremonini, Mirjam Cvetič, and Ioannis Papadimitriou

JHEP, 2018

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We analytically compute the thermoelectric conductivities at zero frequency (DC) in the holographic dual of a four dimensional Einstein-Maxwell-Axion-Dilaton theory that admits a class of asymptotically hyperscaling violating Lifshitz backgrounds with a dynamical exponent z and hyperscaling violating parameter $θ$. We show that the heat current in the dual Lifshitz theory involves the energy flux, which is an irrelevant operator for $z>1$. The linearized fluctuations relevant for computing the thermoelectric conductivities turn on a source for this irrelevant operator, leading to several novel and non-trivial aspects in the holographic renormalization procedure and the identification of the physical observables in the dual theory. Moreover, imposing Dirichlet or Neumann boundary conditions on the spatial components of one of the two Maxwell fields present leads to different thermoelectric conductivities. Dirichlet boundary conditions reproduce the thermoelectric DC conductivities obtained from the near horizon analysis of Donos and Gauntlett, while Neumann boundary conditions result in a new set of DC conductivities. We make preliminary analytical estimates for the temperature behavior of the thermoelectric matrix in appropriate regions of parameter space. In particular, at large temperatures we find that the only case which could lead to a linear resistivity $ρ∼T$ corresponds to $z=4/3$.
@article{Cremonini:2018jrx, category = {article}, author = {Cremonini, Sera and Cvetič, Mirjam and Papadimitriou, Ioannis}, title = {Thermoelectric DC conductivities in hyperscaling violating Lifshitz theories}, arxiv = {1801.04284}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P18004, UPR-1288-T}, journal = {JHEP}, volume = {04}, pages = {099}, year = {2018}, doi = {10.1007/JHEP04(2018)099}, dimensions = {true}, }
JHEP
Entropy functional and the holographic attractor mechanism

Alejandro Cabo-Bizet, Uri Kol, Leopoldo A. Pando Zayas, Ioannis Papadimitriou, and Vimal Rathee

JHEP, 2018

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We provide a field theory interpretation of the attractor mechanism for asymptotically AdS$_4$ dyonic BPS black holes whose entropy is captured by the supersymmetric index of the twisted ABJM theory at Chern-Simons level one. We holographically compute the renormalized off-shell quantum effective action in the twisted ABJM theory as a function of the supersymmetric fermion masses and the arbitrary vacuum expectation values of the dimension one scalar bilinear operators and show that extremizing the effective action with respect to the vacuum expectation values of the dimension one scalar bilinears is equivalent to the attractor mechanism in the bulk. In fact, we show that the holographic quantum effective action coincides with the entropy functional and, therefore, its value at the extremum reproduces the black hole entropy.
@article{Cabo-Bizet:2017xdr, category = {article}, author = {Cabo-Bizet, Alejandro and Kol, Uri and Pando Zayas, Leopoldo A. and Papadimitriou, Ioannis and Rathee, Vimal}, title = {Entropy functional and the holographic attractor mechanism}, arxiv = {1712.01849}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {KIAS-P17130, LCTP-17-07}, journal = {JHEP}, volume = {05}, pages = {155}, year = {2018}, doi = {10.1007/JHEP05(2018)155}, dimensions = {true}, }

2017

JHEP
Supercurrent anomalies in 4d SCFTs

Ioannis Papadimitriou

JHEP, 2017

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We use holographic renormalization of minimal $\mathcal{N} = 2$ gauged supergravity in order to derive the general form of the quantum Ward identities for 3d $\mathcal{N} = 2$ and 4d $\mathcal{N} = 1$ superconformal theories on general curved backgrounds, including an arbitrary fermionic source for the supercurrent. The Ward identities for 4d $\mathcal{N} = 1$ theories contain both bosonic and fermionic global anomalies, which we determine explicitly up to quadratic order in the supercurrent source. The Ward identities we derive apply to any superconformal theory, independently of whether it admits a holographic dual, except for the specific values of the $a$ and $c$ anomaly coefficients, which are equal due to our starting point of a two-derivative bulk supergravity theory. We show that the fermionic anomalies lead to an anomalous transformation of the supercurrent under rigid supersymmetry on backgrounds admitting Killing spinors, even if all superconformal anomalies are numerically zero on such backgrounds. The anomalous transformation of the supercurrent under rigid supersymmetry leads to an obstruction to the Q-exactness of the stress tensor in supersymmetric vacua, and may have implications for the applicability of localization techniques. We use this obstruction to the Q-exactness of the stress tensor, together with the Ward identities, in order to determine the general form of the stress tensor and R-current one-point functions in supersymmetric vacua, which allows us to obtain general expressions for the supersymmetric Casimir charges and partition function.
@article{Papadimitriou:2017kzw, category = {article}, author = {Papadimitriou, Ioannis}, title = {Supercurrent anomalies in 4d SCFTs}, arxiv = {1703.04299}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {SISSA-12-2017-FISI}, journal = {JHEP}, volume = {07}, pages = {038}, year = {2017}, doi = {10.1007/JHEP07(2017)038}, dimensions = {true}, }
JHEP
Phases of planar AdS black holes with axionic charge

Marco M. Caldarelli, Ariana Christodoulou, Ioannis Papadimitriou, and Kostas Skenderis

JHEP, 2017

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Planar AdS black holes with axionic charge have finite DC conductivity due to momentum relaxation. We obtain a new family of exact asymptotically AdS$_4$ black branes with scalar hair, carrying magnetic and axion charge, and we study the thermodynamics and dynamic stability of these, as well as of a number of previously known electric and dyonic solutions with axion charge and scalar hair. The scalar hair for all solutions satisfy mixed boundary conditions, which lead to modified holographic Ward identities, conserved charges and free energy, relative to those following from the more standard Dirichlet boundary conditions. We show that properly accounting for the scalar boundary conditions leads to well defined first law and other thermodynamic relations. Finally, we compute the holographic quantum effective potential for the dual scalar operator and show that dynamical stability of the hairy black branes is equivalent to positivity of the energy density.
@article{Caldarelli:2016nni, category = {article}, author = {Caldarelli, Marco M. and Christodoulou, Ariana and Papadimitriou, Ioannis and Skenderis, Kostas}, title = {Phases of planar AdS black holes with axionic charge}, arxiv = {1612.07214}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {SISSA-59-2016-FISI}, journal = {JHEP}, volume = {04}, pages = {001}, year = {2017}, doi = {10.1007/JHEP04(2017)001}, dimensions = {true}, }
JHEP
Two-point Functions in a Holographic Kondo Model

Johanna Erdmenger, Carlos Hoyos, Andy O'Bannon, Ioannis Papadimitriou, Jonas Probst, and Jackson M. S. Wu

JHEP, 2017

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We develop the formalism of holographic renormalization to compute two-point functions in a holographic Kondo model. The model describes a $(0+1)$-dimensional impurity spin of a gauged $SU(N)$ interacting with a $(1+1)$-dimensional, large-$N$, strongly-coupled Conformal Field Theory (CFT). We describe the impurity using Abrikosov pseudo-fermions, and define an $SU(N)$-invariant scalar operator $\mathcal{O}$ built from a pseudo-fermion and a CFT fermion. At large $N$ the Kondo interaction is of the form $\mathcal{O}^{\dagger} \mathcal{O}$, which is marginally relevant, and generates a Renormalization Group (RG) flow at the impurity. A second-order mean-field phase transition occurs in which $\mathcal{O}$ condenses below a critical temperature, leading to the Kondo effect, including screening of the impurity. Via holography, the phase transition is dual to holographic superconductivity in $(1+1)$-dimensional Anti-de Sitter space. At all temperatures, spectral functions of $\mathcal{O}$ exhibit a Fano resonance, characteristic of a continuum of states interacting with an isolated resonance. In contrast to Fano resonances observed for example in quantum dots, our continuum and resonance arise from a $(0+1)$-dimensional UV fixed point and RG flow, respectively. In the low-temperature phase, the resonance comes from a pole in the Green's function of the form $-i \langle {\cal O} \rangle^2$, which is characteristic of a Kondo resonance.
@article{Erdmenger:2016jjg, category = {article}, author = {Erdmenger, Johanna and Hoyos, Carlos and O'Bannon, Andy and Papadimitriou, Ioannis and Probst, Jonas and Wu, Jackson M. S.}, title = {Two-point Functions in a Holographic Kondo Model}, arxiv = {1612.02005}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {OUTP-16-27P, SISSA-61-2016-FISI, FPAUO-16-16}, journal = {JHEP}, volume = {03}, pages = {039}, year = {2017}, doi = {10.1007/JHEP03(2017)039}, dimensions = {true}, }
PRD
Holographic Kondo and Fano Resonances

Johanna Erdmenger, Carlos Hoyos, Andy O'Bannon, Ioannis Papadimitriou, Jonas Probst, and Jackson M. S. Wu

Phys. Rev. D, 2017

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We use holography to study a $(1+1)$-dimensional Conformal Field Theory (CFT) coupled to an impurity. The CFT is an $SU(N)$ gauge theory at large $N$, with strong gauge interactions. The impurity is an $SU(N)$ spin. We trigger an impurity Renormalization Group (RG) flow via a Kondo coupling. The Kondo effect occurs only below the critical temperature of a large-$N$ mean-field transition. We show that at all temperatures $T$, impurity spectral functions exhibit a Fano resonance, which in the low-$T$ phase is a large-$N$ manifestation of the Kondo resonance. We thus provide an example in which the Kondo resonance survives strong correlations, and uncover a novel mechanism for generating Fano resonances, via RG flows between $(0 + 1)$-dimensional fixed points.
@article{Erdmenger:2016vud, category = {article}, author = {Erdmenger, Johanna and Hoyos, Carlos and O'Bannon, Andy and Papadimitriou, Ioannis and Probst, Jonas and Wu, Jackson M. S.}, title = {Holographic Kondo and Fano Resonances}, arxiv = {1611.09368}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {FPAUO-16-15, OUTP-16-26P, SISSA-60-2016-FISI}, journal = {Phys. Rev. D}, volume = {96}, number = {2}, pages = {021901}, year = {2017}, doi = {10.1103/PhysRevD.96.021901}, dimensions = {true}, }

2016

JHEP
AdS$_{2}$ holographic dictionary

Mirjam Cvetič, and Ioannis Papadimitriou

JHEP, 2016

[Erratum: JHEP 01, 120 (2017)]

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We construct the holographic dictionary for both running and constant dilaton solutions of the 2D Einstein-Maxwell-Dilaton theory obtained by a circle reduction from 3D gravity with negative cosmological constant. This specific model ensures that the dual theory has a well defined ultraviolet completion in terms of a 2D CFT, but our results apply qualitatively to a wider class of 2D dilaton gravity theories. For each type of solutions we perform holographic renormalization, compute the exact renormalized one-point functions in the presence of arbitrary sources, and derive the asymptotic symmetries and conserved charges. In both cases we find that the scalar operator dual to the dilaton plays a crucial role in the description of the dynamics. Its source gives rise to a matter conformal anomaly for the running dilaton solutions, while its expectation value is the only non trivial observable for constant dilaton solutions. The role of this operator has been largely overlooked in the literature. We further show that the only non trivial conserved charges for running dilaton solutions are the mass and the electric charge, while for constant dilaton solutions only the electric charge is non zero. However, by uplifting the solutions to three dimensions we show that constant dilaton solutions can support non trivial extended symmetry algebras, including the one found by Compère, Song and Strominger, in agreement with results by Castro and Song. Finally, we demonstrate that any solution of this specific dilaton gravity model can be uplifted to a family of asymptotically AdS$_2\times S^2$ or conformally AdS$_2\times S^2$ solutions of the STU model in four dimensions. The four dimensional solutions obtained by uplifting the running dilaton solutions coincide with the so called `subtracted geometries', while those obtained from the uplift of the constant dilaton ones are new.
@article{Cvetic:2016eiv, category = {article}, author = {Cvetič, Mirjam and Papadimitriou, Ioannis}, title = {AdS$_{2}$ holographic dictionary}, arxiv = {1608.07018}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {UPR-1281-T, SISSA-44-2016-FISI}, journal = {JHEP}, volume = {12}, pages = {008}, year = {2016}, doi = {10.1007/JHEP12(2016)008}, dimensions = {true}, note = {[Erratum: JHEP 01, 120 (2017)]} }
JHEP
Thermodynamics, transport and relaxation in non-conformal theories

Maximilian Attems, Jorge Casalderrey-Solana, David Mateos, Ioannis Papadimitriou, Daniel Santos-Oliván, Carlos F. Sopuerta, Miquel Triana, and Miguel Zilhão

JHEP, 2016

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We study the equilibrium and near-equilibrium properties of a holographic five-dimensional model consisting of Einstein gravity coupled to a scalar field with a non-trivial potential. The dual four-dimensional gauge theory is not conformal and, at zero temperature, exhibits a renormalisation group flow between two different fixed points. We quantify the deviations from conformality both in terms of thermodynamic observables and in terms of the bulk viscosity of the theory. The ratio of bulk over shear viscosity violates Buchel's bound. We study relaxation of small-amplitude, homogeneous perturbations by computing the quasi-normal modes of the system at zero spatial momentum. In this approximation we identify two different relaxation channels. At high temperatures, the different pressures first become approximately equal to one another, and subsequently this average pressure evolves towards the equilibrium value dictated by the equation of state. At low temperatures, the average pressure first evolves towards the equilibrium pressure, and only later the different pressures become approximately equal to one another.
@article{Attems:2016ugt, category = {article}, author = {Attems, Maximilian and Casalderrey-Solana, Jorge and Mateos, David and Papadimitriou, Ioannis and Santos-Oliván, Daniel and Sopuerta, Carlos F. and Triana, Miquel and Zilhão, Miguel}, title = {Thermodynamics, transport and relaxation in non-conformal theories}, arxiv = {1603.01254}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {ICCUB-16-011, SISSA-17-2016-FISI}, journal = {JHEP}, volume = {10}, pages = {155}, year = {2016}, doi = {10.1007/JHEP10(2016)155}, dimensions = {true}, }
JHEP
Black hole thermodynamics from a variational principle: Asymptotically conical backgrounds

Ok Song An, Mirjam Cvetič, and Ioannis Papadimitriou

JHEP, 2016

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The variational problem of gravity theories is directly related to black hole thermodynamics. For asymptotically locally AdS backgrounds it is known that holographic renormalization results in a variational principle in terms of equivalence classes of boundary data under the local asymptotic symmetries of the theory, which automatically leads to finite conserved charges satisfying the first law of thermodynamics. We show that this connection holds well beyond asymptotically AdS black holes. In particular, we formulate the variational problem for $\mathcal{N}=2$ STU supergravity in four dimensions with boundary conditions corresponding to those obeyed by the so called `subtracted geometries'. We show that such boundary conditions can be imposed covariantly in terms of a set of asymptotic second class constraints, and we derive the appropriate boundary terms that render the variational problem well posed in two different duality frames of the STU model. This allows us to define finite conserved charges associated with any asymptotic Killing vector and to demonstrate that these charges satisfy the Smarr formula and the first law of thermodynamics. Moreover, by uplifting the theory to five dimensions and then reducing on a 2-sphere, we provide a precise map between the thermodynamic observables of the subtracted geometries and those of the BTZ black hole. Surface terms play a crucial role in this identification.
@article{An:2016fzu, category = {article}, author = {An, Ok Song and Cvetič, Mirjam and Papadimitriou, Ioannis}, title = {Black hole thermodynamics from a variational principle: Asymptotically conical backgrounds}, arxiv = {1602.01508}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {SISSA-04-2016-FISI, UPR-1277-T}, journal = {JHEP}, volume = {03}, pages = {086}, year = {2016}, doi = {10.1007/JHEP03(2016)086}, dimensions = {true}, }
JHEP
A Holographic Two-Impurity Kondo Model

Andy O'Bannon, Ioannis Papadimitriou, and Jonas Probst

JHEP, 2016

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We propose a model of a strongly-interacting two-impurity Kondo system based on the AdS/CFT correspondence, also known as holography. In a Landau Fermi Liquid, the single-impurity Kondo effect is the screening of an impurity spin at low temperature $T$. The two-impurity Kondo model then describes the competition between the Kondo interaction and the Heisenberg interaction between two impurity spins, also called the RKKY interaction. For spin-$1/2$ impurities, that competition leads to a quantum phase transition from a Kondo-screened phase to a phase in which the two impurity spins screen one another. Our holographic model is based on a $(1+1)$-dimensional CFT description of the two-impurity Kondo model, reliable for two impurities with negligible separation in space. We consider only impurity spins in a totally anti-symmetric representation of an $SU(N)$ spin symmetry. We employ a large-$N$ limit, in which both Kondo and RKKY couplings are double-trace, and both Kondo and inter-impurity screening appear as condensation of single-trace operators at the impurities' location. We perform the holographic renormalization of our model, which allows us to identify the Kondo and RKKY couplings as boundary conditions on fields in AdS. We numerically compute the phase diagram of our model in the plane of RKKY coupling versus $T$, finding evidence for a quantum phase transition from a trivial phase, with neither Kondo nor inter-impurity screening, to a non-trivial phase, with both Kondo and anti-ferromagnetic inter-impurity screening. More generally we show, just using $SU(N)$ representation theory, that ferromagnetic correlations must be absent at leading order in the large-$N$ limit. Our holographic model may be useful for studying many open problems involving strongly-interacting quantum impurities, including for example the Kondo lattice, relevant for describing the heavy fermion compounds.
@article{OBannon:2015cqy, category = {article}, author = {O'Bannon, Andy and Papadimitriou, Ioannis and Probst, Jonas}, title = {A Holographic Two-Impurity Kondo Model}, arxiv = {1510.08123}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {OUTP-15-28P, SISSA-49-2015-FISI}, journal = {JHEP}, volume = {01}, pages = {103}, year = {2016}, doi = {10.1007/JHEP01(2016)103}, dimensions = {true}, }

2015

JHEP
A goldstino at the bottom of the cascade

Matteo Bertolini, Daniele Musso, Ioannis Papadimitriou, and Himanshu Raj

JHEP, 2015

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Working within a five-dimensional consistent truncation of type IIB supergravity dimensionally reduced on $T^{1,1}$, we consider supersymmetry breaking solutions with the asymptotics of the supersymmetric Klebanov-Strassler background. There exists a two-parameter family of such solutions. Within this family, we show that those (and only those) solutions related to antiD-branes at the tip of the conifold correspond to dual field theory vacua where a goldstino mode is present and supercurrent Ward identities hold. Our findings do not depend on the IR singularity of the dual backgrounds, nor on its resolution. As such, they constitute an independent, necessary check for the existence of supersymmetry breaking vacua in the conifold cascading gauge theory. Our analysis relies on a holographic derivation of the Ward identities which has a wider applicability, beyond the specific system and symmetries considered here.
@article{Bertolini:2015hua, category = {article}, author = {Bertolini, Matteo and Musso, Daniele and Papadimitriou, Ioannis and Raj, Himanshu}, title = {A goldstino at the bottom of the cascade}, arxiv = {1509.03594}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {SISSA-40-2015-FISI}, journal = {JHEP}, volume = {11}, pages = {184}, year = {2015}, doi = {10.1007/JHEP11(2015)184}, dimensions = {true}, }
JHEP
Holographic Hall conductivities from dyonic backgrounds

Jonathan Lindgren, Ioannis Papadimitriou, Anastasios Taliotis, and Joris Vanhoof

JHEP, 2015

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We develop a general framework for computing the holographic 2-point functions and the corresponding conductivities in asymptotically locally AdS backgrounds with an electric charge density, a constant magentic field, and possibly non-trivial scalar profiles, for a broad class of Einstein-Maxwell-Axion-Dilaton theories, including certain Chern-Simons terms. Holographic renormalization is carried out for any theory in this class and the computation of the renormalized AC conductivities at zero spatial momentum is reduced to solving a single decoupled first order Riccati equation. Moreover, we develop a first order fake supergravity formulalism for dyonic renormalization group flows in four dimensions, allowing us to construct analytically infinite families of such backgrounds by specifying a superpotential at will. These RG flows interpolate between AdS$_4$ in the UV and a hyperscaling violating Lifshitz geometry in the IR with exponents $1<z<3$ and $\theta=z+1$. For $1<z<2$ the spectrum of fluctuations is gapped and discrete. Our hope and intention is that this analysis can serve as a manual for computing the holographic 1- and 2-point functions and the corresponding transport coefficients in any dyonic background, both in the context of AdS/CMT and AdS/QCD.
@article{Lindgren:2015lia, category = {article}, author = {Lindgren, Jonathan and Papadimitriou, Ioannis and Taliotis, Anastasios and Vanhoof, Joris}, title = {Holographic Hall conductivities from dyonic backgrounds}, arxiv = {1505.04131}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {SISSA-15-2015-FISI}, journal = {JHEP}, volume = {07}, pages = {094}, year = {2015}, doi = {10.1007/JHEP07(2015)094}, dimensions = {true}, }
JHEP
Lifshitz holography: The whole shebang

Wissam Chemissany, and Ioannis Papadimitriou

JHEP, 2015

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We provide a general algorithm for constructing the holographic dictionary for any asymptotically locally Lifshitz background, with or without hyperscaling violation, and for any values of the dynamical exponents $z$ and $\theta$, as well as the vector hyperscaling violating exponent, that are compatible with the null energy condition. The analysis is carried out for a very general bottom up model of gravity coupled to a massive vector field and a dilaton with arbitrary scalar couplings. The solution of the radial Hamilton-Jacobi equation is obtained recursively in the form of a graded expansion in eigenfunctions of two commuting operators, which are the appropriate generalization of the dilatation operator for non scale invariant and Lorentz violating boundary conditions. The Fefferman-Graham expansions, the sources and 1-point functions of the dual operators, the Ward identities, as well as the local counterterms required for holographic renormalization all follow from this asymptotic solution of the radial Hamilton-Jacobi equation. We also find a family of exact backgrounds with $z>1$ and $\theta>0$ corresponding to a marginal deformation shifting the vector hyperscaling violating parameter and we present an example where the conformal anomaly contains the only $z=2$ conformal invariant in $d=2$ with four spatial derivatives.
@article{Chemissany:2014xsa, category = {article}, author = {Chemissany, Wissam and Papadimitriou, Ioannis}, title = {Lifshitz holography: The whole shebang}, arxiv = {1408.0795}, archiveprefix = {arXiv}, primaryclass = {hep-th}, doi = {10.1007/JHEP01(2015)052}, journal = {JHEP}, volume = {01}, pages = {052}, year = {2015}, dimensions = {true}, }

2014

PLB
Generalized dilatation operator method for non-relativistic holography

Wissam Chemissany, and Ioannis Papadimitriou

Phys. Lett. B, 2014

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We present a general algorithm for constructing the holographic dictionary for Lifshitz and hyperscaling violating Lifshitz backgrounds for any value of the dynamical exponent $z$ and any value of the hyperscaling violation parameter $\theta$ compatible with the null energy condition. The objective of the algorithm is the construction of the general asymptotic solution of the radial Hamilton-Jacobi equation subject to the desired boundary conditions, from which the full dictionary can be subsequently derived. Contrary to the relativistic case, we find that a fully covariant construction of the asymptotic solution for running non-relativistic theories necessitates an expansion in the eigenfunctions of two commuting operators instead of one. This provides a covariant but non-relativistic grading of the expansion, according to the number of time derivatives.
@article{Chemissany:2014xpa, category = {article}, author = {Chemissany, Wissam and Papadimitriou, Ioannis}, title = {Generalized dilatation operator method for non-relativistic holography}, arxiv = {1405.3965}, archiveprefix = {arXiv}, primaryclass = {hep-th}, journal = {Phys. Lett. B}, volume = {737}, pages = {272--276}, year = {2014}, doi = {10.1016/j.physletb.2014.08.057}, dimensions = {true}, }
JHEP
Riccati equations for holographic 2-point functions

Ioannis Papadimitriou, and Anastasios Taliotis

JHEP, 2014

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Any second order homogeneous linear ordinary differential equation can be transformed into a first order non-linear Riccati equation. We argue that the Riccati form of the linearized fluctuation equations that determine the holographic 2-point functions simplifies considerably the numerical computation of such 2-point functions and of the corresponding transport coefficients by computing directly the response functions, eliminating the arbitrary source from the start. Moreover, it provides a neat criterion for the infrared regularity of the fluctuations. In particular, it is shown that the infrared regularity conditions for scalar and tensor fluctuations coincide, and hence they are either both regular or both singular. We demonstrate our numerical recipe based on the Riccati equations by computing the holographic 2-point functions for the stress tensor and a scalar operator in a number of asymptotically anti de Sitter backgrounds of bottom up scalar-gravity models. Analytical results are obtained for the 2-point function of the transverse traceless part of the stress tensor in two confining geometries, including a geometry that belongs to the class of IHQCD. We find that in this background the spin-2 spectrum is linear and, as expected, the position space 2-point function decays exponentially at large distances at a rate proportional to the confinement scale.
@article{Papadimitriou:2013jca, category = {article}, author = {Papadimitriou, Ioannis and Taliotis, Anastasios}, title = {Riccati equations for holographic 2-point functions}, arxiv = {1312.7876}, archiveprefix = {arXiv}, primaryclass = {hep-th}, journal = {JHEP}, volume = {04}, pages = {194}, year = {2014}, doi = {10.1007/JHEP04(2014)194}, dimensions = {true}, }

2013

JHEP
Bootstrapping gravity solutions

João Aparicio, Daniel Grumiller, Esperanza Lopez, Ioannis Papadimitriou, and Stefan Stricker

JHEP, 2013

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We construct an algorithm to determine all stationary axi-symmetric solutions of 3-dimensional Einstein gravity with a minimally coupled self-interacting scalar field. We holographically renormalize the theory and evaluate then the on-shell action as well as the stress tensor and scalar one-point functions. We study thermodynamics, derive two universal formulas for the entropy and prove that global AdS provides a lower bound for the mass of certain solitons. Several examples are given in detail, including the first instance of locally asymptotically flat hairy black holes and novel asymptotically AdS solutions with non-Brown-Henneaux behavior.
@article{Aparicio:2012yq, category = {article}, author = {Aparicio, João and Grumiller, Daniel and Lopez, Esperanza and Papadimitriou, Ioannis and Stricker, Stefan}, title = {Bootstrapping gravity solutions}, arxiv = {1212.3609}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {TUW-12-26, IFT-UAM-CSIC-12-109}, doi = {10.1007/JHEP05(2013)128}, journal = {JHEP}, volume = {05}, pages = {128}, year = {2013}, dimensions = {true}, }

2011

JHEP
Holographic Renormalization of general dilaton-axion gravity

Ioannis Papadimitriou

JHEP, 2011

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We consider a very general dilaton-axion system coupled to Einstein-Hilbert gravity in arbitrary dimension and we carry out holographic renormalization for any dimension up to and including five dimensions. This is achieved by developing a new systematic algorithm for iteratively solving the radial Hamilton-Jacobi equation in a derivative expansion. The boundary term derived is valid not only for asymptotically AdS backgrounds, but also for more general asymptotics, including non-conformal branes and Improved Holographic QCD. In the second half of the paper, we apply the general result to Improved Holographic QCD with arbitrary dilaton potential. In particular, we derive the generalized Fefferman-Graham asymptotic expansions and provide a proof of the holographic Ward identities.
@article{Papadimitriou:2011qb, category = {article}, author = {Papadimitriou, Ioannis}, title = {Holographic Renormalization of general dilaton-axion gravity}, arxiv = {1106.4826}, archiveprefix = {arXiv}, primaryclass = {hep-th}, journal = {JHEP}, volume = {08}, pages = {119}, year = {2011}, doi = {10.1007/JHEP08(2011)119}, dimensions = {true}, }
NPB
The warped, resolved, deformed conifold gets flavoured

Jerome Gaillard, Dario Martelli, Carlos Núñez, and Ioannis Papadimitriou

Nucl. Phys. B, 2011

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We discuss a simple transformation that allows to generate SU(3) structure solutions of Type IIB supergravity with RR fluxes, starting from non-Kahler solutions of Type I supergravity. The method may be applied also in the presence of supersymmetric source branes. We apply this transformation to a solution describing fivebranes wrapped on the two-sphere of the resolved conifold with additional flavour fivebrane sources. The resulting solution is a generalisation of the resolved deformed conifold solution of Butti et al. by the addition of D5 brane and D3 brane sources. We propose that this solution may be interpreted in terms of a combined effect of Higgsing and cascade of Seiberg dualities in the dual field theory.
@article{Gaillard:2010qg, category = {article}, author = {Gaillard, Jerome and Martelli, Dario and Núñez, Carlos and Papadimitriou, Ioannis}, title = {The warped, resolved, deformed conifold gets flavoured}, arxiv = {1004.4638}, archiveprefix = {arXiv}, primaryclass = {hep-th}, journal = {Nucl. Phys. B}, volume = {843}, pages = {1--45}, year = {2011}, doi = {10.1016/j.nuclphysb.2010.09.011}, dimensions = {true}, }

2010

JHEP
Holographic renormalization as a canonical transformation

Ioannis Papadimitriou

JHEP, 2010

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The gauge/string dualities have drawn attention to a class of variational problems on a boundary at infinity, which are not well defined unless a certain boundary term is added to the classical action. In the context of supergravity in asymptotically AdS spaces these problems are systematically addressed by the method of holographic renormalization. We argue that this class of a priori ill defined variational problems extends far beyond the realm of holographic dualities. As we show, exactly the same issues arise in gravity in non asymptotically AdS spaces, in point particles with certain unbounded from below potentials, and even fundamental strings in flat or AdS backgrounds. We show that the variational problem in all such cases can be made well defined by the following procedure, which is intrinsic to the system in question and does not rely on the existence of a holographically dual theory: (i) The first step is the construction of the space of the most general asymptotic solutions of the classical equations of motion that inherits a well defined symplectic form from that on phase space. The requirement of a well defined symplectic form is essential and often leads to a necessary repackaging of the degrees of freedom. (ii) Once the space of asymptotic solutions has been constructed in terms of the correct degrees of freedom, then there exists a boundary term that is obtained as a certain solution of the Hamilton-Jacobi equation which simultaneously makes the variational problem well defined and preserves the symplectic form. This procedure is identical to holographic renormalization in the case of asymptotically AdS gravity, but it is applicable to any Hamiltonian system.
@article{Papadimitriou:2010as, category = {article}, author = {Papadimitriou, Ioannis}, title = {Holographic renormalization as a canonical transformation}, arxiv = {1007.4592}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {CERN-PH-TH-2010-154}, doi = {10.1007/JHEP11(2010)014}, journal = {JHEP}, volume = {11}, pages = {014}, year = {2010}, dimensions = {true}, }
IJMPA
Walking Dynamics from String Duals

Carlos Núñez, Ioannis Papadimitriou, and Maurizio Piai

Int. J. Mod. Phys. A, 2010

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Within the context of a String Theory dual to $\mathcal{N}=1$ gauge theories with gauge group $SU(N_c)$ and large $N_c$, we identify a class of solutions of the background equations for which a suitably defined dual of the gauge coupling exhibits the features of a walking theory. We find evidence for three distinct, dynamically generated scales, characterizing walking, symmetry breaking and confinement, and we put them in correspondence with field theory by an analysis of the operators driving the flow.
@article{Nunez:2008wi, category = {article}, author = {Núñez, Carlos and Papadimitriou, Ioannis and Piai, Maurizio}, title = {Walking Dynamics from String Duals}, arxiv = {0812.3655}, archiveprefix = {arXiv}, primaryclass = {hep-th}, doi = {10.1142/S0217751X10049189}, journal = {Int. J. Mod. Phys. A}, volume = {25}, pages = {2837--2865}, year = {2010}, dimensions = {true}, }

2008

PRD
Comments on the String dual to $\mathcal{N} = 1$ SQCD

Carlos Hoyos-Badajoz, Carlos Núñez, and Ioannis Papadimitriou

Phys. Rev. D, 2008

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We study the String dual to $\mathcal{N} = 1$ SQCD deformed by a quartic superpotential in the quark superfields. We present a unified view of the previous results in the literature and find new exact solutions and new asymptotic solutions. Then we study the Physics encoded in these backgrounds, giving among other things a resolution to an old puzzle related to the beta function and a sufficient criteria for screening. We also extend our results to the $SO(N_c)$ case where we present a candidate for the Wilson loop in the spinorial representation. Various aspects of this line of research are critically analyzed.
@article{Hoyos-Badajoz:2008znk, category = {article}, author = {Hoyos-Badajoz, Carlos and Núñez, Carlos and Papadimitriou, Ioannis}, title = {Comments on the String dual to $\mathcal{N} = 1$ SQCD}, arxiv = {0807.3039}, archiveprefix = {arXiv}, primaryclass = {hep-th}, journal = {Phys. Rev. D}, volume = {78}, pages = {086005}, year = {2008}, doi = {10.1103/PhysRevD.78.086005}, dimensions = {true}, }

2007

JHEP
Multi-Trace Deformations in AdS/CFT: Exploring the Vacuum Structure of the Deformed CFT

Ioannis Papadimitriou

JHEP, 2007

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We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to `mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying `mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of `mixed' boundary conditions.
@article{Papadimitriou:2007sj, category = {article}, author = {Papadimitriou, Ioannis}, title = {Multi-Trace Deformations in AdS/CFT: Exploring the Vacuum Structure of the Deformed CFT}, arxiv = {hep-th/0703152}, archiveprefix = {arXiv}, reportnumber = {DESY-06-218, ZMP-HH-06-17}, journal = {JHEP}, volume = {05}, pages = {075}, year = {2007}, doi = {10.1088/1126-6708/2007/05/075}, dimensions = {true}, }
PRL
Conformally Coupled Scalars, Instantons and Vacuum Instability in AdS$_4$

Sebastian Haro, Ioannis Papadimitriou, and Anastasios C. Petkou

Phys. Rev. Lett., 2007

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We show that a scalar field conformally coupled to AdS gravity in four dimensions with a quartic self-interaction can be embedded into M-theory. The holographic effective potential is exactly calculated, allowing us to study non-perturbatively the stability of AdS$_4$ in the presence of the conformally coupled scalar. It is shown that there exists a one-parameter family of conformal scalar boundary conditions for which the boundary theory has an unstable vacuum. In this case, the bulk theory has instanton solutions that mediate the decay of the AdS$_4$ space. These results match nicely with the vacuum structure and the existence of instantons in an effective three-dimensional boundary model.
@article{deHaro:2006ymc, category = {article}, author = {de Haro, Sebastian and Papadimitriou, Ioannis and Petkou, Anastasios C.}, title = {Conformally Coupled Scalars, Instantons and Vacuum Instability in AdS$_4$}, arxiv = {hep-th/0611315}, archiveprefix = {arXiv}, reportnumber = {DESY-06-213}, journal = {Phys. Rev. Lett.}, volume = {98}, pages = {231601}, year = {2007}, doi = {10.1103/PhysRevLett.98.231601}, dimensions = {true}, }
JHEP
Non-Supersymmetric Membrane Flows from Fake Supergravity and Multi-Trace Deformations

Ioannis Papadimitriou

JHEP, 2007

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We use fake supergravity as a solution generating technique to obtain a continuum of non-supersymmetric asymptotically $AdS_4\times S^7$ domain wall solutions of eleven-dimensional supergravity with non-trivial scalars in the $SL(8,\mathbb{R})/SO(8)$ coset. These solutions are continuously connected to the supersymmetric domain walls describing a uniform sector of the Coulomb branch of the $M2$-brane theory. We also provide a general argument that under certain conditions identifies the fake superpotential with the exact large-$N$ quantum effective potential of the dual theory, describing a marginal multi-trace deformation. This identification strongly motivates further study of fake supergravity as a solution generating method and it allows us to interpret our non-supersymmetric solutions as a family of marginal triple-trace deformations of the Coulomb branch that completely break supersymmetry and to calculate the exact large-$N$ anomalous dimensions of the operators involved. The holographic one- and two-point functions for these solutions are also computed.
@article{Papadimitriou:2006dr, category = {article}, author = {Papadimitriou, Ioannis}, title = {Non-Supersymmetric Membrane Flows from Fake Supergravity and Multi-Trace Deformations}, arxiv = {hep-th/0606038}, archiveprefix = {arXiv}, reportnumber = {DESY-06-083, ZMP-HH-06-09}, journal = {JHEP}, volume = {02}, pages = {008}, year = {2007}, doi = {10.1088/1126-6708/2007/02/008}, dimensions = {true}, }

2005

JHEP
Thermodynamics of asymptotically locally AdS spacetimes

Ioannis Papadimitriou, and Kostas Skenderis

JHEP, 2005

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We formulate the variational problem for AdS gravity with Dirichlet boundary conditions and demonstrate that the covariant counterterms are necessary to make the variational problem well-posed. The holographic charges associated with asymptotic symmetries are then rederived via Noether's theorem and `covariant phase space' techniques. This allows us to prove the first law of black hole mechanics for general asymptotically locally AdS black hole spacetimes. We illustrate our discussion by computing the conserved charges and verifying the first law for the four dimensional Kerr-Newman-AdS and the five dimensional Kerr-AdS black holes.
@article{Papadimitriou:2005ii, category = {article}, author = {Papadimitriou, Ioannis and Skenderis, Kostas}, title = {Thermodynamics of asymptotically locally AdS spacetimes}, arxiv = {hep-th/0505190}, archiveprefix = {arXiv}, reportnumber = {ITFA-2005-18}, journal = {JHEP}, volume = {08}, pages = {004}, year = {2005}, doi = {10.1088/1126-6708/2005/08/004}, dimensions = {true}, }

2004

JHEP
Correlation functions in holographic RG flows

Ioannis Papadimitriou, and Kostas Skenderis

JHEP, 2004

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We discuss the computation of correlation functions in holographic RG flows. The method utilizes a recently developed Hamiltonian version of holographic renormalization and it is more efficient than previous methods. A significant simplification concerns the treatment of infinities: instead of performing a general analysis of counterterms, we develop a method where only the contribution of counterterms to any given correlator needs to be computed. For instance, the computation of renormalized 2-point functions requires only an analysis at the linearized level. We illustrate the method by discussing flat and AdS-sliced domain walls. In particular, we discuss correlation functions of the Janus solution, a recently discovered non-supersymmetric but stable AdS-sliced domain wall.
@article{Papadimitriou:2004rz, category = {article}, author = {Papadimitriou, Ioannis and Skenderis, Kostas}, title = {Correlation functions in holographic RG flows}, arxiv = {hep-th/0407071}, archiveprefix = {arXiv}, reportnumber = {ITFA-2004-23}, journal = {JHEP}, volume = {10}, pages = {075}, year = {2004}, doi = {10.1088/1126-6708/2004/10/075}, dimensions = {true}, }

2003

PRD
Conformal field theory couplings for intersecting D-branes on orientifolds

Mirjam Cvetič, and Ioannis Papadimitriou

Phys. Rev. D, 2003

[Erratum: Phys.Rev.D 70, 029903 (2004)]

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We present a conformal field theory calculation of four-point and three-point correlation functions for the bosonic twist fields arising at the intersections of D-branes wrapping (supersymmetric) homology cycles of Type II orientifold compactifications. Both the quantum contribution from local excitations at the intersections and the world-sheet disk instanton corrections are computed. As a consequence we obtain the complete expression for the Yukawa couplings of chiral fermions with the Higgs fields. The four-point correlation functions in turn lead to the determination of the four-point couplings in the effective theory, and may be of phenomenological interest.
@article{Cvetic:2003ch, category = {article}, author = {Cvetič, Mirjam and Papadimitriou, Ioannis}, title = {Conformal field theory couplings for intersecting D-branes on orientifolds}, arxiv = {hep-th/0303083}, archiveprefix = {arXiv}, reportnumber = {UPR-1028-T, PUPT-2076}, journal = {Phys. Rev. D}, volume = {68}, pages = {046001}, year = {2003}, doi = {10.1103/PhysRevD.70.029903}, dimensions = {true}, note = {[Erratum: Phys.Rev.D 70, 029903 (2004)]} }
PRD
More supersymmetric standard - like models from intersecting D6-branes on type IIA orientifolds

Mirjam Cvetič, and Ioannis Papadimitriou

Phys. Rev. D, 2003

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We present new classes of supersymmetric Standard-like models from type IIA $\mathbb{T}^6/(\mathbb{Z}_2\times \mathbb{Z}_2)$ orientifold with intersecting D6-branes. D6-branes can wrap general supersymmetric three-cycles of $\mathbb{T}^6=\mathbb{T}^2\times \mathbb{T}^2\times \mathbb{T}^2$, and any $\mathbb{T}^2$ is allowed to be tilted. The models still suffer from additional exotics, however we obtained solutions with fewer Higgs doublets, as well as models with all three families of left-handed quarks and leptons arising from the same intersecting sector, and examples of a genuine left-right symmetric model with three copies of left-handed and right-handed families of quarks and leptons.
@article{Cvetic:2003xs, category = {article}, author = {Cvetič, Mirjam and Papadimitriou, Ioannis}, arxiv = {hep-th/0303197}, archiveprefix = {arXiv}, reportnumber = {UPR-1029-T, PUPT-2078}, journal = {Phys. Rev. D}, volume = {67}, pages = {126006}, year = {2003}, doi = {10.1103/PhysRevD.67.126006}, dimensions = {true}, }
NPB
Supersymmetric three family SU(5) grand unified models from type IIA orientifolds with intersecting D6-branes

Mirjam Cvetič, Ioannis Papadimitriou, and Gary Shiu

Nucl. Phys. B, 2003

[Erratum: Nucl.Phys.B 696, 298--298 (2004)]

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We construct some $\mathcal{N} = 1$ supersymmetric three-family SU(5) Grand Unified Models from type IIA orientifolds on $\mathbb{T}^6/(\mathbb{Z}_2\times \mathbb{Z}_2)$ with D6-branes intersecting at general angles. These constructions are supersymmetric only for special choices of untwisted moduli. We show that within the above class of constructions there are no supersymmetric three-family models with 3 copies of ${\bf 10}$-plets unless there are simultaneously some ${\bf 15}$-plets. We systematically analyze the construction of such models and their spectra. The M-theory lifts of these brane constructions become purely geometrical backgrounds: they are singular $G_2$ manifolds where the Grand Unified gauge symmetries and three families of chiral fermions are localized at codimension 4 and codimension 7 singularities respectively. We also study somepreliminary phenomenological features of the models.
@article{Cvetic:2002pj, category = {article}, author = {Cvetič, Mirjam and Papadimitriou, Ioannis and Shiu, Gary}, arxiv = {hep-th/0212177}, archiveprefix = {arXiv}, reportnumber = {RUNHETC-2002-47, UPR-1023-T, PUPT-2068, MAD-TH-02-4}, journal = {Nucl. Phys. B}, volume = {659}, pages = {193--223}, year = {2003}, doi = {10.1016/j.nuclphysb.2004.06.041}, dimensions = {true}, note = {[Erratum: Nucl.Phys.B 696, 298--298 (2004)]} }

2000

JPB
Simple model for the laser cooling of an ion in a Penning trap

Richard C. Thompson, and John Papadimitriou

J. Phys. B: At. Mol. Opt. Phys., 2000

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We present a model for laser cooling of a single ion in the Penning trap. The model solves the equations of motion in the presence of the damping caused by the interaction with the laser beam, and predicts for the first time the dependence of the cooling rates for the two radial degrees of freedom in the trap as a function of the laser detuning, laser beam offset and saturation parameter. The conditions derived for both radial degrees of freedom to be cooled simultaneously agree with those found in earlier studies. The results indicate that under conditions where both motions are cooled simultaneously, the cooling rates are both significantly smaller than the maximum rate for either motion considered in isolation. Furthermore, the magnetron cooling rate is typically much lower than the cyclotron cooling rate, as has been found in experiments. The model indicates how the cooling rate for a single ion may be optimized.
@article{R C Thompson_2000, category = {article}, author = {Thompson, Richard C. and Papadimitriou, John}, title = {Simple model for the laser cooling of an ion in a Penning trap}, reportnumber = {}, journal = {J. Phys. B: At. Mol. Opt. Phys.}, volume = {33}, pages = {3393-3405}, year = {2000}, doi = {10.1088/0953-4075/33/17/317}, dimensions = {true}, }

refereed conference proceedings

2016

SPP
Lectures on Holographic Renormalization

Ioannis Papadimitriou

Springer Proc. Phys., 2016

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We provide a pedagogical introduction to the method of holographic renormalization, in its Hamiltonian incarnation. We begin by reviewing the description of local observables, global symmetries, and ultraviolet divergences in local quantum field theories, in a language that does not require a weak coupling Lagrangian description. In particular, we review the formulation of the Renormalization Group as a Hamiltonian flow, which allows us to present the holographic dictionary in a precise and suggestive language. The method of holographic renormalization is then introduced by first computing the renormalized two-point function of a scalar operator in conformal field theory and comparing with the holographic computation. We then proceed with the general method, formulating the bulk theory in a radial Hamiltonian language and deriving the Hamilton–Jacobi equation. Two methods for solving recursively the Hamilton–Jacobi equation are then presented, based on covariant expansions in eigenfunctions of certain functional operators on the space of field theory couplings. These algorithms constitute the core of the method of holographic renormalization and allow us to obtain the holographic Ward identities and the asymptotic expansions of the bulk fields.
@article{Papadimitriou:2016yit, category = {proceedings}, author = {Papadimitriou, Ioannis}, editor = {Kallosh, Renata and Orazi, Emanuele}, title = {Lectures on Holographic Renormalization}, journal = {Springer Proc. Phys.}, volume = {176}, pages = {131--181}, year = {2016}, doi = {10.1007/978-3-319-31352-8_4}, dimensions = {true}, }
NPPP
Hyperscaling violating Lifshitz holography

Ioannis Papadimitriou

Nucl. Part. Phys. Proc., 2016

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We present an overview of the construction of the general holographic dictionary for asymptotically locally Lifshitz and hyperscaling violating Lifshitz backgrounds with arbitrary dynamical exponents $z$ and $\theta$, compatible with the null energy condition, which was recently developed in arXiv:1405.3965, arXiv:1408.0795. A concrete definition of asymptotically locally Lifshitz and hyperscaling violating Lifshitz backgrounds is provided in the context of a generic bottom-up Einstein-Proca-Dilaton theory, and a systematic procedure for solving the radial Hamilton-Jacobi equation via a covariant expansion in eigenfunctions of two commuting operators is presented. The resulting asymptotic solution of the Hamilton-Jacobi equation is subsequently used to derive the full holographic dictionary, including the Fefferman-Graham asymptotic expansions and the non-relativistic holographic Ward identities.
@article{Papadimitriou:2014lia, category = {proceedings}, author = {Papadimitriou, Ioannis}, editor = {Aguilar-Benítez, M. and Fuster, J. and Martí-García, S. and Santamaría, A.}, title = {Hyperscaling violating Lifshitz holography}, arxiv = {1411.0312}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {IFT-UAM-CSIC-14-110, SISSA-55-2014-FISI}, journal = {Nucl. Part. Phys. Proc.}, volume = {273-275}, pages = {1487--1493}, year = {2016}, doi = {10.1016/j.nuclphysbps.2015.09.240}, dimensions = {true}, }

2012

FP
Holographic Cosmological Backgrounds, Wilson Loop (De)confinement and Dilaton Singularities

Johanna Erdmenger, Kazuo Ghoroku, Rene Meyer, and Ioannis Papadimitriou

Fortsch. Phys., 2012

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We review a construction of holographic geometries dual to $\mathcal{N}=4$ SYM theory on a Friedmann-Robertson-Walker background and in the presence or absence of a gluon condensate and instanton density. We find the most general solution with arbitrary scale factor and show that it is diffeomorphic to topological black holes. We introduce a time-dependent boundary cosmological constant $\lambda(t)$ and show energy-momentum conservation in this background. For constant $\lambda$, the deconfinement properties of the temporal Wilson loop are analysed. In most cases the Wilson loop confines throughout cosmological evolution. However, there is an exceptional case which shows a transition from deconfinement at early times to confinement at late times. We classify the presence or absence of horizons, with important implications for the Wilson loop.
@article{Erdmenger:2012yh, category = {proceedings}, author = {Erdmenger, Johanna and Ghoroku, Kazuo and Meyer, Rene and Papadimitriou, Ioannis}, editor = {Sorokin, Dimitri and Luest, Dieter}, title = {Holographic Cosmological Backgrounds, Wilson Loop (De)confinement and Dilaton Singularities}, arxiv = {1205.0677}, archiveprefix = {arXiv}, primaryclass = {hep-th}, reportnumber = {CCTP-2012-04, IFT-UAM-CSIC-12-26, KIAS-P12021}, journal = {Fortsch. Phys.}, volume = {60}, pages = {991--997}, year = {2012}, doi = {10.1002/prop.201200072}, dimensions = {true}, }

2005

IRMA
AdS/CFT correspondence and geometry

Ioannis Papadimitriou, and Kostas Skenderis

IRMA Lect. Math. Theor. Phys., 2005

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In the first part of this paper we provide a short introduction to the AdS/CFT correspondence and to holographic renormalization. We discuss how QFT correlation functions, Ward identities and anomalies are encoded in the bulk geometry. In the second part we develop a Hamiltonian approach to the method of holographic renormalization, with the radial coordinate playing the role of time. In this approach regularized correlation functions are related to canonical momenta and the near-boundary expansions of the standard approach are replaced by covariant expansions where the various terms are organized according to their dilatation weight. This leads to universal expressions for counterterms and one-point functions (in the presence of sources) that are valid in all dimensions. The new approach combines optimally elements from all previous methods and supersedes them in efficiency.
@article{Papadimitriou:2004ap, category = {proceedings}, author = {Papadimitriou, Ioannis and Skenderis, Kostas}, editor = {Biquard, O.}, title = {AdS/CFT correspondence and geometry}, arxiv = {hep-th/0404176}, archiveprefix = {arXiv}, reportnumber = {ITFA-2004-17}, journal = {IRMA Lect. Math. Theor. Phys.}, volume = {8}, pages = {73--101}, year = {2005}, doi = {10.4171/013-1/4}, dimensions = {true}, }
SS
Holographic renormalization made simple: An example

Ioannis Papadimitriou

Subnucl. Ser., 2005

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We present an alternative method to obtain the exact solution of the bulk field equations for a free scalar field in fixed Euclidean AdS$_{d+1}$ with prescribed but arbitrary Dirichlet boundary conditions. We demonstrate that the Dirichlet boundary conditions allow for a reduction of the second order field equations to a first order problem. The approach is meant to highlight the key points underlying the general method we present in [1], which is a simpler version of what is known as ‘holographic renorinalization’ in the context of the AdS/CFT correspondence. The example we discuss here is special in that an exact solution of the bulk field equations can be obtained and hence the full quantum effective action of the boundary theory can be calculated exactly.
@article{Papadimitriou:2003is, category = {proceedings}, author = {Papadimitriou, Ioannis}, editor = {Zichichi, A.}, title = {Holographic renormalization made simple: An example}, journal = {Subnucl. Ser.}, volume = {41}, pages = {508--514}, year = {2005}, doi = {10.1142/9789812701794_0021}, dimensions = {true}, }

theses

2005

Ph.D.

Aspects of the gauge gravity duality and holography

Ioannis Papadimitriou

University of Amsterdam, 2005

Bib HTML

@phdthesis{Papadimitriou:2005tia,
  category = {thesis},
  author = {Papadimitriou, Ioannis},
  title = {Aspects of the gauge gravity duality and holography},
  school = {University of Amsterdam},
  year = {2005},
  isbn = {9064642567},
}

2000

M.Sc.
Optimization of order parameters in lattice SU(2) gauge theory using the linear delta expansion

Ioannis Papadimitriou

Imperial College London, 2000

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The linear $δ$-expansion is applied to the calculation of order parameters in lattice SU(2) pure gauge theory and all the diagrams up to order four are tabulated. The principle of minimal sensitivity is applied to fix the variational parameters. The results are satisfactory for zero temperature, but at finite temperature there are indications that the method fails to produce a valid expansion in the region where a second order phase transition is expected.
@phdthesis{Papadimitriou_MSci_thesis, category = {thesis}, author = {Papadimitriou, Ioannis}, title = {Optimization of order parameters in lattice SU(2) gauge theory using the linear delta expansion}, school = {Imperial College London}, year = {2000}, }