In this study, we investigate a scenario based on the effects of the Loop Quantum Gravity (LQG) on the electromagnetic sector of the Standard Model of Fundamental Interactions and Particle Physics (SM). Starting from a post-Maxwellian version of electromagnetism that includes LQG effects, we derive and discuss the influence of LQG parameters on classical quantities such as the components of the stress-tensor. Furthermore, we inspect the propagation of electromagnetic waves and examine the optical properties of the QED vacuum in this scenario. Among these, we contemplate the combined effect of the LQG parameters and a homogeneous background magnetic field on the propagation of electromagnetic waves by considering issues such as group velocities and refractive indices of the QED vacuum, in detail. Finally, with the aid of the previously analyzed LQG-extended photonic dispersion relations, we re-discuss the kinematics of the Compton effect and conclude that an interesting nonlinear profile emerges in the wavelengths of the incoming and deflected photons.

Brazil

P.A.L. Mourão

G.L.L.W. Levy

J.A. Helayël-Neto

Reassessing aspects of LQG-modified dispersion relations of photons * P. A. L. Mourão is support by CAPES. G. L. L. W. L. Levy is support by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Grant No. E-26/202.437/2024.

Holographic models that consider classical vector fields in a 5-d background provide effective descriptions for heavy vector meson spectra. This is true both in vacuum and a thermal medium, such as quark gluon plasma. However, the manner in which these phenomenological models work is unclear. In particular, what is the role of the fifth dimension, and what is the relation between the holographic 5-d background and physical (4-d) heavy mesons? Hadrons, in contrast to leptons, are composite particles with some internal structure that depends on the energy at which they are observed. In this study, a static meson is represented by a heavy quark-antiquark pair with an interaction described by a Nambu Goto string existing in the same 5-d background that provides field solutions leading to masses and decay constants of charmonium states. The resulting interaction potential is linear for large distances, with a string tension consistent with the effective Cornell potential. Introducing temperature $\textit{T}$ in the background, it is found for the $J/\psi$ case that there is a deconfining transition at some critical value of $\textit{T}$. The obtained results indicate that the 5-d background effectively represents the internal structure of the (static) charmonium (quasi) states.

Nelson R.F. Braga

Yan F. Ferreira

William S. Cunha

Holography and the internal structure of charmonium * The authors are partially supported by CNPq — Conselho Nacional de Desenvolvimento Científico e Tecnologico, by FAPERJ — Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro and by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior — Brasil (CAPES), Finance Code 001

In the framework of six-dimensional conformal field theories with   <math> <mi>N</mi> <mo>=</mo> <mfenced> <mrow> <mn>1</mn> <mo>,</mo> <mspace width="0.25em"></mspace> <mn>0</mn> </mrow> </mfenced> </math>  $$ \mathcal{N}=\left(1,\ 0\right) $$  supersymmetry we develop the map between the holographic description, the field theoretical description and the associated Hanany-Witten set-ups. General expressions that calculate various observables are presented. The study of string solitons singles out a special background of Massive IIA on which we show (by explicitly finding a Lax pair) that the Neveu-Schwarz part of the string sigma model is classically integrable. We study the particular dual conformal field theory and compute some of its observables.

United Kingdom

Kostas Filippas

Carlos Núñez

Jeroen Gorsel

Integrability and holographic aspects of six-dimensional   <math> <mi>N</mi> <mo>=</mo> <mfenced> <mrow> <mn>1</mn> <mo>,</mo> <mspace width="0.25em"></mspace> <mn>0</mn> </mrow> </mfenced> </math>  $$ \mathcal{N}=\left(1,\ 0\right) $$  superconformal field theories

we study the holographic description of <math><mi>N</mi><mo>=</mo><mn>2</mn></math> Super Conformal Field Theories in four dimensions first given by Gaiotto and Maldacena. We present new expressions that holographically calculate characteristic numbers of the CFT and associated Hanany-Witten set-ups, or more dynamical observables, like the central charge. A number of examples of varying complexity are studied and some proofs for these new expressions are presented. We repeat this treatment for the case of the marginally deformed Gaiotto-Maldacena theories, presenting an infinite family of new solutions and compute some of its observables. These new backgrounds rely on the solution of a Laplace equation and a boundary condition, encoding the kinematics of the original conformal field theory.

India

Dibakar Roychowdhury

Stefano Speziali

China

Salomón Zacarías

Holographic aspects of four dimensional SCFTs and their marginal deformations

In this work we study various aspects of six-dimensional  <math><mi>N</mi></math> $$ \mathcal{N} $$ = (1, 0) SCFTs. We consider the construction of their string duals in Massive IIA and discuss some observables in given examples. We study the dynamics of string solitons wrapping and rotating on the Massive IIA background and show that the associated Hamiltonian system is both non-integrable and chaotic, implying the non-integrability of the dual CFT. Our procedure is analytic, using well developed mathematical techniques, and numerical, by the explicit calculation of power spectra, Lyapunov coefficients and Poincaré sections.

Spain

José Penín

The non-integrability of strings in massive type IIA and their holographic duals

We consider the backgrounds obtained by Abelian and non-Abelian T-duality applied on AdS 5 × S 5. We study geodesics, calculate Penrose limits and find the associated plane-wave geometries. We quantise the weakly coupled type-IIA string theory on these backgrounds. We study the BMN sector, finding operators that wrap the original quiver CFT. For the non-Abelian plane wave, we find a ‘flow’ in the frequencies. We report some progress to understand this, in terms of deconstruction of a higher dimensional field theory. We explore a relation with the plane-wave limit of the Janus solution, which we also provide.

Georgios Itsios

Horatiu Nastase

CERN

Greece

Konstantinos Sfetsos

Penrose limits of Abelian and non-Abelian T-duals of AdS 5 × S 5 and their field theory duals

Recently, a duality web for three dimensional theories with Chern–Simons terms was proposed. This can be derived from a single bosonization type duality, for which various supporting arguments (but not a proof) were given. Here we explicitly derive this bosonization, in the Abelian case and for a particular regime of parameters. To do this, we use the particle-vortex duality in combination with a Buscher-like duality (both considered in the regime of low energies). As a corollary, Son's conjectured duality is derived in a somewhat singular limit of vanishing mass.

Deriving three-dimensional bosonization and the duality web

In this paper we study an AdS 5 solution constructed using non-Abelian T-duality, acting on the Klebanov-Witten background. We show that this is dual to a linear quiver with two tails of gauge groups of increasing rank. The field theory dynamics arises from a D4-NS5-NS5’ brane set-up, generalizing the constructions discussed by Bah and Bobev. These realize N = 1 $$ \mathcal{N}=1 $$ quiver gauge theories built out of N = 1 $$ \mathcal{N}=1 $$ and N = 2 $$ \mathcal{N}=2 $$ vector multiplets flowing to interacting fixed points in the infrared. We compute the central charge using a -maximization, and show its precise agreement with the holographic calculation. Our result exhibits n 3 scaling with the number of five-branes. This suggests an eleven-dimensional interpretation in terms of M5-branes, a generic feature of various AdS backgrounds obtained via non-Abelian T-duality.

Yolanda Lozano

Jesús Montero

The AdS 5 non-Abelian T-dual of Klebanov-Witten as a N = 1 $$ \mathcal{N}=1 $$ linear quiver from M5-branes

Acting with non-Abelian T-duality on the S 3 inside the AdS 5 subspace of AdS 5 × S 5 with N units of flux, we generate a new half-BPS solution with SU(2|4) symmetry that belongs to the Lin-Lunin-Maldacena class of geometries. The analysis of the asymptotics, quantised charges and probe branes in this geometry suggests an interpretation as the gravity dual to the Berenstein-Maldacena-Nastase Plane Wave Matrix Model, in a particular vacuum associated to a partition of N , in which the multiplicity of each SU(2) irreducible representation is equal to its dimension. This vacuum is interpreted in M-theory in terms of giant gravitons backreacting in the maximally supersymmetric pp-wave geometry. Consistently with this, we show that the non-Abelian T-dual solution exactly agrees with the Penrose limit of the superstar solution in AdS 7 × S 4 . This suggests an interesting global completion of the non-Abelian T-dual solution in terms of an M5-brane geometry.

BMN vacua, superstars and non-abelian T-duality

In this work we study mesonic excitations in a Quantum Field Theory dual to the non Abelian T-dual of AdS 5 × S 5 , using a D 6 brane probe on the Sfetsos-Thompson background. Before and after the duality, we observe interesting differences between the spectra and interpret them. The spectrum of masses and the interactions between mesonic excitations teach valuable lessons about the character of non-Abelian T-duality and its implications for Holography. The case of Abelian T-duality is also studied.