We construct a new family of quantum chaotic models by combining multiple copies of integrable commuting SYK models. As each copy of the commuting SYK model does not commute with others, this construction breaks the integrability of each commuting SYK and the family of models demonstrates the emergence of quantum chaos. We study the spectrum of this model analytically in the double-scaled limit. As the number of copies tends to infinity, the spectrum becomes compact and equivalent to the regular SYK model. For finite <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> copies, the spectrum is close to the regular SYK model in UV but has an exponential tail <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>e</mi><mrow><mi>E</mi><mo>/</mo><msub><mi>T</mi><mi>c</mi></msub></mrow></msup></math> in the IR. We identify the reciprocal of the exponent in the tail as a critical temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math>, above which the model should be quantum chaotic. <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math> monotonically decreases as <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> increases, which expands the chaotic regime over the nonchaotic regime. We propose the existence of a new phase around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mi>c</mi></msub></math>, and the dynamics should be very different in two phases. We further carry out numeric analysis at finite <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math>, which supports our proposal. Given any finite dimensional local Hamiltonian, by decomposing it into <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>d</mi></math> groups, in which all terms in one group commute with each other but terms from different groups may not, our analysis can give an estimate of the critical temperature for quantum chaos based on the decomposition. We also comment on the implication of the critical temperature to future quantum simulations of quantum chaos and quantum gravity.

United States

Ping Gao

China

Han Lin

Cheng Peng

Quantum chaos from multiple copies of integrable commuting SYK models

When combining apparently inconsistentexperimental results, one often implements errors on errors. The Particle Data Group’s phenomenological prescription offers a practical solution but lacks a firm theoretical foundation. To address this, D’Agostini and Cowan have proposed Bayesian and frequentist approaches, respectively, both introducing gamma-distributed auxiliary variables to model uncertainty in quoted errors. In this Letter, we show that these two formulations admit a parameter-by-parameter correspondence, and are structurally equivalent. This identification clarifies how Bayesian prior choices can be interpreted in terms of frequentist sampling assumptions, providing a unified probabilistic framework for modeling uncertainty in quoted variances.

Japan

Satoshi Mishima

Kin-ya Oda

Implementing errors on errors: Bayesian vs frequentist

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.

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 couplings of axionlike particles (ALPs) to Standard Model fermions are proportional to the fermion masses, making the interaction with the top quark particularly significant. In this study, we consider an ALP that is a mixture of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-even and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-odd components, thereby introducing <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation. This <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math> violation, in turn, gives rise to electric dipole moments (EDMs) of quarks and leptons, as well as chromoelectric dipole moments (CEDMs) of quarks. We compute the one-loop and two-loop contributions to the top quark CEDM induced by the ALP. In our calculation, we treat the external gluon as off shell with momentum <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup><mo>≠</mo><mn>0</mn></math>, derive the analytical results, and finally evaluate the top quark CEDM at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>q</mi><mn>2</mn></msup><mo>=</mo><msubsup><mi>m</mi><mi>t</mi><mn>2</mn></msubsup></math>, corresponding to the top quark pole mass. This value is relevant for subsequent calculations of the EDMs of the neutron and mercury. By applying current experimental bounds on EDMs and CEDMs, we derive constraints on the ALP-top quark coupling, with the strongest limit coming from the neutron EDM.

Subhadip Bisal

Constraining ALP-top interaction from the chromoelectric dipole moment of the top quark

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

The KM3NeT Collaboration recently announced the detection of a neutrino with energy 220 PeV. One possible source of such ultrahigh-energy particles is the rapid emission of energetic Hawking radiation from a primordial black hole (PBH) near the end of its evaporation lifetime. The mass distribution for PBHs features a power-law tail for small masses; a small subset of PBHs would be undergoing late-stage evaporation today. We find that recent high-energy neutrino events detected by the IceCube and KM3NeT Collaborations, with energies <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi mathvariant="script">O</mi><mo stretchy="false">(</mo><mn>1</mn><mo>−</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>2</mn></mrow></msup><mo stretchy="false">)</mo><mtext> </mtext><mtext> </mtext><mi>PeV</mi></mrow></math>, are consistent with event-rate expectations if a significant fraction of the dark matter consists of PBHs.

Alexandra P. Klipfel

David I. Kaiser

Ultrahigh-Energy Neutrinos from Primordial Black Holes

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.

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 investigate the classical stability of two coupled scalar fields with opposite-sign kinetic terms evolving in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>+</mo><mn>1</mn></mrow></math> dimensional Minkowski spacetime. In the first part, we characterize unquenched ghostly interactions and present numerical solutions that support the following statements. First, the classical instability is not instantaneous and can even be benign, i.e., free of finite-time singularities. Second, while the classical instability can cascade toward higher frequency excitations, it is not driven by high frequency modes: At fixed amplitude, high-frequency modes are more stable than low-frequency modes. In the second part, we demonstrate that the classical instability can be quenched by mass terms. In particular, we exemplify that heavy high-frequency ghost fields seem to not violate the decoupling theorem and can be integrated out classically. In the third part, we demonstrate how self-interactions can quench the instability, for instance, by postponing its onset to parametrically large times. Extrapolating numerical results at large but finite evolution time to infinite evolution time, we demonstrate that classical fluctuations around trivial and nontrivial field-theory vacua are increasingly long-lived with (i) smaller initial amplitude of fluctuations, (ii) higher initial frequency of fluctuations, (iii) larger masses of the fields, or (iv) weaker interaction coupling. Moreover, our numerical simulations for field-theoretical generalizations of some globally stable ghostly mechanical models do not feature any instability.

Cédric Deffayet

Aaron Held

Shinji Mukohyama

Czechia

Alexander Vikman

Ghostly interactions in (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>1</mn><mo>+</mo><mn>1</mn></mrow></math>)-dimensional classical field theory