We develop a nonperturbative definition of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>RMT</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math>: a generalization of random matrix theory that is compatible with the symmetries of two-dimensional conformal field theory. Given any random matrix ensemble, its <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi></math>-point spectral correlations admit a prescribed modular-invariant lift to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>RMT</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math>, which moreover reduce to the original random matrix correlators in a near-extremal limit. Central to the prescription is a presentation of random matrix theory in Mellin space, which lifts to two dimensions via the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>SL</mi><mo stretchy="false">(</mo><mn>2</mn><mo>,</mo><mi mathvariant="double-struck">Z</mi><mo stretchy="false">)</mo></math> spectral decomposition employed in previous work. As a demonstration we perform the explicit <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>RMT</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> lift of two-point correlations of the GUE Airy model. We propose that in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math> pure gravity, semiclassical amplitudes for off-shell <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>n</mi></math>-boundary torus wormholes with topology <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi mathvariant="normal">Σ</mi></mrow><mrow><mn>0</mn><mo>,</mo><mi>n</mi></mrow></msub><mo>×</mo><msup><mrow><mi>S</mi></mrow><mrow><mn>1</mn></mrow></msup></mrow></math> are given by the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>RMT</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> lift of JT gravity wormhole amplitudes. For the three-boundary case, we identify a gravity calculation which matches the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>RMT</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow></math> result.

United States

Jan Boruch

France

Gabriele Di Ubaldo

United Kingdom

Felix M. Haehl

Eric Perlmutter

Canada

Moshe Rozali

Modular-Invariant Random Matrix Theory and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>AdS</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math> Wormholes

The Minkowski vacuum in an accelerated frame behaves like a fluid that has not only a finite temperature due to the Unruh effect, but also a finite shear viscosity. Moreover, the ratio of this viscosity to the entropy density exactly satisfies the Kovtun-Son-Starinets bound, inspired by the string theory <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>1</mn><mo>/</mo><mn>4</mn><mi>π</mi></math>. The origin of this viscosity is purely kinematical and is believed to be related to entanglement introduced by the Rindler horizon. We directly calculate the viscosity, entropy density, and their ratio for massless fields with spins <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math> and 1. We show that locally the ratio of viscosity to entropy density can be below the limiting value <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1</mn><mo>/</mo><mn>4</mn><mi>π</mi></math> at distances of the order of the thickness of the membrane corresponding to the stretched horizon, and is described by the universal function for different spins. In particular, on the membrane surface <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>η</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>1</mn><mo>/</mo><mn>8</mn><mi>π</mi></math>.

Russia

D.D. Lapygin

JINR

G. Yu. Prokhorov

O.V. Teryaev

V.I. Zakharov

Viscosity, entanglement, and acceleration

In previous work [D. Giusti, et al., Methods for high-precision determinations of radiative-leptonic decay form factors using lattice QCD, <a href="http://dx.doi.org/10.1103/PhysRevD.107.074507">Phys. Rev. D 107, 074507 (2023)</a>], we showed that form factors for radiative leptonic decays of pseudoscalar mesons can be determined efficiently and with high precision from lattice QCD using the “three-dimensional (3D) method,” in which three-point functions are computed for all values of the current insertion time and the time integral is performed at the data-analysis stage. Here, we demonstrate another benefit of the 3D method: the form factors can be extracted for any number of nonzero photon virtualities from the same three-point functions at no extra cost. We present results for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>D</mi><mi>s</mi></msub><mo stretchy="false">→</mo><mo>ℓ</mo><mi>ν</mi><msup><mi>γ</mi><mo>*</mo></msup></math> vector form factor as a function of photon energy and photon virtuality, for both positive and negative virtuality, for a single ensemble with 340 MeV pion mass and 0.11 fm lattice spacing. In our analysis, we separately consider the two different time orderings and the different quark flavors in the electromagnetic current. We discuss in detail the behavior of the unwanted exponentials contributing to the three-point functions, as well as the choice of fit models and fit ranges used to remove them for various values of the virtuality. While positive photon virtuality is relevant for decays to multiple charged leptons, negative photon virtuality suppresses soft contributions and is of interest in QCD-factorization studies of the form factors.

Germany

Davide Giusti

Christopher F. Kane

Christoph Lehner

Stefan Meinel

Amarjit Soni

Efficient lattice QCD computation of radiative-leptonic-decay form factors at multiple positive and negative photon virtualities

While charged lepton-flavor-violating tau decays to strange mesons provide powerful probes of the underlying <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi><mo stretchy="false">→</mo><mo>ℓ</mo><mi>d</mi><mover accent="true"><mi>s</mi><mo stretchy="false">¯</mo></mover></math> transition, the corresponding decay modes involving hyperons are kinematically forbidden. To address this gap, we propose the quasielastic scattering processes <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>N</mi><mo stretchy="false">→</mo><msup><mi>τ</mi><mo>−</mo></msup><mi>Y</mi></math>. Within a general low-energy effective Lagrangian, we perform a comprehensive analysis of the final-state polarizations of both the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>τ</mi></math> lepton and the hyperon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Y</mi></math>, systematically addressing the theoretical uncertainty driven by the model dependence of form factors. Our analysis demonstrates that while this uncertainty leads to large variations in predicted rates, the polarization observables can potentially distinguish between the form factor models, and help to determine the chiral nature of the vectorial new physics interaction. Finally, we forecast the event rates for future facilities, revealing a strong dependence on the form factor models, with predicted yields ranging from potentially observable levels to rates far below current detection thresholds.

China

Xin-Shuai Yan

Zhen-Qing Hu

Qin Chang

Ya-Dong Yang

Polarization probes of new physics in lepton-flavor-violating hyperon production from <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mo>−</mo></msup><mi>N</mi><mo stretchy="false">→</mo><msup><mi>τ</mi><mo>−</mo></msup><mi>Y</mi></math> scattering

This paper demonstrates how the Veneziano partial amplitude of Bosonic string theory admits a generalization to world-(hyper)surfaces of any dimension <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>. In particular, for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi><mo>=</mo><mn>2</mn></math>, by carving up the worldsheet integral according to stipulations imposed on conformal cross ratios, the Virasoro-Shapiro full amplitude can be decomposed into a sum of three partial amplitudes. The amplitudes obtained on generalizing the Veneziano amplitude all contain tachyons. To explore candidate tachyon-free and supersymmetric versions of these amplitudes, a new bootstrap principle is introduced and applied, which demands that towers of residues alternate between all-even and all-odd spin partial waves.

South Korea

Christian Baadsgaard Jepsen

Veneziano amplitude in any dimension and a Virasoro-Shapiro partial amplitude

We study a class of Sachdev, Ye, and Kitaev (SYK) models with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>2</mn></math> supersymmetry, described by <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> fermions in chiral Fermi multiplets, as well as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>α</mi><mi>N</mi></math> first-order bosons in chiral multiplets. The interactions are characterized by two integers <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mo stretchy="false">(</mo><mi>p</mi><mo>,</mo><mi>q</mi><mo stretchy="false">)</mo></math>. We focus on the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>N</mi></math> and low energy limit of these models. Despite the presence of dynamical bosons, we find conformal behavior akin to the standard SYK model. We use <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">I</mi></math>-extremization of a Witten index to study the supersymmetric solutions. In particular, we find an exact expression for the entropy, which matches the numerical solutions to the Schwinger-Dyson equations. We further solve the model both in the large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi></math> and large <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>p</mi></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>q</mi></mrow></math> limits. Numerically, we verify our analytical results and obtain estimates for the Schwarzian coupling in the near zero-temperature limit. We also study the low-lying spectrum of operators to determine the parameter ranges where the Schwarzian mode dominates the IR dynamics. Lastly, we study out-of-time-ordered correlators to show that the model is maximally chaotic.

Italy

Francesco Benini

Tomás Reis

Saman Soltani

Ziruo Zhang

<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>2</mn></math> SYK models with dynamical bosons and fermions

This work introduces a field-theoretical model designed to simulate the presence of material layers with magnetoelectric properties. The model comprises the standard Maxwell field coupled to a Chern-Simons field confined to a planar layer. The electromagnetic behavior of the boundary is emulated through the interaction between the Chern-Simons and Maxwell fields, governed by two parameters: the Chern-Simons mass and the coupling constant between the fields. Both parameters can be adjusted to reflect the specific properties of different materials. We compute the exact propagator of the theory and employ it to investigate several physical properties. Our analysis focuses on phenomena that arise from the presence of external sources coupled to both the Maxwell and Chern-Simons fields, considering various scenarios. In the Chern-Simons sector, the sources emulate defects in the crystal lattice of the material layer. The main objective of this paper is to present the proposed model and to explore its behavior in the simple context of a single planar material interface. We also suggest possible extensions of the model to more general configurations.

Brazil

F.A. Barone

H.L. Oliveira

J.P. Ferreira

Two-gauge field model for magnetoelectric boundaries

Seeking mass patterns is a key to decoding the unknown flavor puzzles in particle physics. Inspired by quark hierarchical masses, the mass matrix can universally be factorized into a family-diagonal phase matrix $$K_L^q$$ and a real symmetric matrix $$M_N^q$$ characterized by only two parameters. The factorized structure provides model-independent rules to the mass matrix. We demonstrate that the large $$\delta _{CP}$$ naturally arises from the degeneracy of the first two quark families in the mass hierarchy limit. As an application, the flat pattern with elements close to unity in the matrix is checked by fitting quark masses and the CKM mixing. It achieves a precise description of flavor structure with minimal parameters.

Ying Zhang

Mass matrix rules and the flat pattern of quarks

In this Letter we propose an interpretation of the Hubble tension as an effect of the scale-running of cosmological parameters and fundamental constants, as the Newton’s constant $\textit{G}$ and the cosmological constant $$\Lambda $$ . Namely, the tension between $$H_0$$ measurements by CMB and Supernovae observations would be a consequence of the fact that the value of $$H_0$$ depends (due to the running of $\textit{G}$ and $$\Lambda $$ ) on the scale at which it is measured. Indeed, the two different values of the Hubble parameter $\textit{today}$ correspond to the two different cosmological scales at which Supernovae and CMB measurements probe our universe. We discuss some possible theoretical scenarios in which the running of $\textit{G}$ and $$\Lambda $$ can occur. We stress that one should interpret such a running as a scale-dependence of the cosmological parameters and fundamental constants at the same time rather than a time dependence, as it is usually considered in the literature.

Fabio Briscese

The Hubble tension as an effect of the renormalization of fundamental constants and cosmological parameters

Flux compactifications of IIA supergravity on orientifolded $$\hbox {G}_2$$ -manifolds have been argued to allow for classical $$\hbox {Minkowski}_3$$ vacua with moduli and scale-separated $$\hbox {AdS}_3$$ vacua with full moduli stabilisation. To further uplift these vacua to meta-stable $$\hbox {dS}_3$$ vacua using anti-D2 branes, warped throats are desirable. We study the flux-stabilisation of local “CGLP-type” throats in compact $$\hbox {G}_2$$ spaces, and discuss consistency constraints on anti-brane uplifting. Despite the classical $$\hbox {AdS}_3$$ vacua being free of tachyons, we find that uplifting from anti-branes down warped throats is forbidden. If instead we rely on hypothetical $$\hbox {AdS}_3$$ vacua that arise from quantum corrections to the classical $$\hbox {Minkowski}_3$$ vacua, we find that (similarly to the 4d analogues) consistency constraints point in opposite directions. However, there is potentially an advantage over 4d when it comes to concrete fine-tuning freedom of numbers, such as tadpole constraints.

Greece

Fotis Farakos

George Tringas

Belgium

Thomas Riet

Warped $$\hbox {G}_2$$ -throats in IIA and uplift dSillusions