The particle model building of cosmological collider physics often involves boost-breaking bilinear mixing between a heavy particle and the nearly massless inflaton mode. In cosmological correlators, such a mixing is obtained by taking a folded limit of a generic tree graph, which is a special case of degenerate kinematics. In this work, we continue our exploration of massive inflationary amplitudes with a focus on degenerate kinematics. With a suitable change of variables, we derive new differential equations and full analytical solutions for generic tree graphs, making it trivial to take the folded limit and partial-energy limit at a vertex. Our result shows that folded tree graphs generally involve functions of smaller transcendental weights than their nondegenerate counterparts. In particular, the inflaton bispectrum with triple massive exchanges can be expressed in terms of a trivariate Kampé de Fériet function and simpler hypergeometric functions.

China

Zhong-Zhi Xianyu

Jiaju Zang

Massive inflationary amplitudes: new representations and degenerate limits

We consider the transverse momentum ($\textit{q}$ ) distribution of neutral charged bosons at hadron colliders. We perform the resummation of the logarithmically-enhanced effects due to simultaneous QCD and QED initial-state radiation, up to mixed next-to-next-to-leading logarithmic (NNLL) accuracy. We study the impact of such mixed QCD⊗QED resummed contributions on top of pure QCD corrections, finding percent-level effects.

Spain

Andrea Autieri

Switzerland

Stefano Camarda

Leandro Cieri

Italy

Giancarlo Ferrera

German Sborlini

Transverse-momentum resummation at mixed QCD⊗QED NNLL accuracy for $\textit{Z}$ boson production at hadron colliders

We study spacetime four-point functions of chiral primary operators for superstrings propagating in AdS $\textit{× S}$ $\textit{× T}$ from the worldsheet perspective, allowing for external states with arbitrary spectral flow charges. We work at small boundary cross-ratio and consider both extremal (supersymmetry-protected) and non-extremal configurations. The string correlators involve a non-trivial integration over the worldsheet moduli, and we demonstrate how the exchange of short and long strings is encoded in distinct integration regions. We interpret our results in terms of the operator product expansion in the boundary theory, and make explicit the precise matching with the available data for the relevant holographic correlators.

Argentina

Emiliano Barone

Sergio Iguri

Nicolas Kovensky

Julián Toro

Superstring four-point functions in AdS3 $\textit{× S}$ 3 $\textit{× T}$ 4

We explore baryon-number-violating (|∆$\textit{B}$| = 2) processes beyond the well-known neutron-antineutron ( $$ n-\overline{n} $$ ) oscillations, focusing on the $$ \Lambda -\overline{\Lambda} $$ system. The presence of a strange quark in the Λ baryon introduces a new set of six-quark operators roughly of the form ($\textit{uds}$) , which are different from the ($\textit{udd}$) operators responsible for $$ n-\overline{n} $$ oscillations. Using the Standard Model Effective Field Theory (SMEFT), we classify all dimension-9 operators that cause |∆$\textit{B}$| = 2 transitions and study their UV completions mediated by exotic scalar fields with trilinear interactions. We demonstrate that in these models, $$ \Lambda -\overline{\Lambda} $$ oscillations can occur at tree level, with $$ n-\overline{n} $$ mixing potentially appearing at higher loop levels. We employ a chiral effective theory to constrain the effective mass mixing $\textit{δm}$ , deriving bounds from current experimental limits on $$ n-\overline{n} $$ oscillations and dinucleon decays such as $\textit{pp}$ → $\textit{K}$ $\textit{K}$ . These bounds indicate that $$ \Lambda -\overline{\Lambda} $$ oscillations probe a complementary parameter space, sensitive to baryon-number violation at scales up to 10 − 10 TeV. We show that the existing indirect bounds make it challenging to provide a competitive bound on $\textit{δm}$ at BESIII.

Arnau Beneito

Slovenia

Svjetlana Fajfer

United States

Alexey Petrov

New avenues for $\textit{|}$∆$\textit{B|}$ = 2 processes beyond neutron-antineutron oscillations

Holographic D-brane constructions, governed by the Dirac-Born-Infeld (DBI) action, play a central role in the AdS/CFT correspondence, particularly in applications to quantum chromodynamics and condensed matter systems. In this work, we demonstrate how to equip these bottom-up holographic models with dynamical boundary gauge fields, thereby introducing electromagnetic interactions into their dual field theory descriptions. As a direct application of this formalism, we compute the dispersion relations of the lowest quasinormal modes around both equilibrium and nonequilibrium steady states, and show that their behavior matches the predictions from hydrodynamics with dynamical U(1) symmetry.

Yong Ahn

Matteo Baggioli

Hyun-Sik Jeong

Japan

Masataka Matsumoto

Holographic D-brane constructions with dynamical gauge fields

A number of supersymmetric Jackiw-Teitelboim (JT) gravity theories are known to be described (in the Euclidean path integral formulation) by double-scaled random matrix models. Such matrix models can be characterized using a certain “string equation”. It was shown recently that in extended supergravity, when the number of BPS states scales as $$ {\textrm{e}}^{S_0} $$ , where $\textit{S}$ is the extremal entropy, a special ansatz for the leading order solution of the string equation yields the supergravity spectrum. Somewhat miraculously, the construction showed that the functional form of the non-BPS (continuum) sector predicts the precise form of the BPS sector, showing the robustness of the supergravity/matrix-model correspondence. In this paper, we refine the analysis and show that the string equation, combined with some simple requirements on solutions, are powerful tools for constraining the spectrum of extended JT supergravity theories. We re-explore the cases of $$ \mathcal{N}=2 $$ and (small) $$ \mathcal{N}=4 $$ JT supergravity, and then explore the new cases of spectra from $$ \mathcal{N}=3 $$ and large $$ \mathcal{N}=4 $$ JT supergravity (recently derived by Heydeman, Shi, and Turiaci) showing that our approach also works naturally for (nearly) all the models. Based on this success, we conjecture that these new supergravity models also have matrix model descriptions.

Clifford Johnson

Maciej Kolanowski

Extended JT supergravity and random matrix models: The power of the string equation

In this paper, we initiate the study of lepton flavor violating (LFV) dark matter (DM) interactions, expanding our focus beyond the flavor-conserving DM interactions typically considered in conventional direct and indirect detections. We work in an effective field theory (EFT) framework, focusing on the leading-order local operators of the form, $$ {\overline{\ell}}_j\Gamma {\ell}_i{\textrm{DM}}^2 $$ , where ($\textit{ij}$) = ($\textit{eμ, eτ, μτ}$) and the DM includes the three well-known scenarios: a scalar, a fermion, and a vector. We derive the invariant-mass distribution for the three-body decay $\textit{ℓ}$ → $\textit{ℓ}$ + DM + DM and demonstrate that it can be used to distinguish between different operator structures and to determine the DM mass. By utilizing current experimental bounds on the charged muon LFV decay involving neutrinos and the ratio of tau leptonic decay widths, we establish stringent limits on the effective scale associated with each operator. Additionally, for the $\textit{eμ}$ flavor combination, we investigate the muon four-body radiative decay ($\textit{μ}$ → $\textit{e}$ + DM + DM + $\textit{γ}$) to complement our probe of such interactions. Finally, we examine muonium invisible decays based on the derived bounds on the effective operators and find that the branching ratios can be significantly enhanced compared to the predictions of the standard model. In particular, any future observation of the para-muonium invisible decay serves as a compelling signature for these flavored DM interactions.

Sahabub Jahedi

Yi Liao

Xiao-Dong Ma

Charged lepton flavor violating decays with a pair of light dark matter and muonium invisible decay

We show that the coupling of a massive spin-2 field to undeformed $$ \mathcal{N}=1 $$ supergravity in four dimensions is unique, leading to a specific non-minimal coupling to the Riemann tensor. The massive spin-2 coupling reproduces the one of an oscillator mode in open string theory, while the massive spin-1 coupling includes a higher-derivative term that is expected to violate causality in the background of a gravitational shock wave. We argue that the resolution of causality and the unitarity bound in the Regge limit require the introduction of infinitely many higher-spin fields similar to the Regge trajectories in string theory, therefore providing an argument in favour of the string lamppost principle with minimal supersymmetry in four dimensions. To obtain this result, we construct the general stress-energy tensor multiplet for the massive spin-2 multiplet with $$ \mathcal{N}=1 $$ supersymmetry.

France

Guillaume Bossard

Gabriele Casagrande

Emilian Dudas

Adrien Loty

A unique coupling of the massive spin-2 field to supergravity

The full 245-letter symbol alphabet for all planar massless two-loop six-point Feynman integrals was recently determined in arXiv:2412.19884 and arXiv:2501.01847. In a parallel mathematical development, it was shown in arXiv:2408.14956 that there is an embedding of the cluster algebra associated to the partial flag variety $$ {\mathcal{Fl}}_{2,n-2;n} $$ , which describes the kinematics of $\textit{n}$ massless particles, into that of the Grassmannian Gr($\textit{n}$–2, 2$\textit{n}$–4). In this paper we connect these developments by showing that most of the rational symbol letters can be expressed in terms of flag cluster variables, and that all of the algebraic symbol letters arise from infinite mutation sequences.

Andrzej Pokraka

Marcus Spradlin

Anastasia Volovich

He-Chen Weng

Symbol alphabets in QCD and flag cluster algebras

The Standard Model (SM) of particle physics fails to explain the observed hierarchy in fermion masses or the origin of fermion-flavor structure. We construct a model to explain these observations in the quark sector. We introduce a spectrum of new particles consisting of six of each — massive singlet vector-like quarks (VLQs), singlet scalars, and SU(2)-doublet scalars. SM quark masses are generated when the neutral components of the SU(2)-doublet scalars acquire non-zero vacuum expectation values (VEVs). We impose global symmetries to ensure that Yukawa couplings stay roughly flavor diagonal and democratic (of the same order), as well as to suppress tree-level flavor-changing neutral currents. Quark-mass hierarchy then follows from a hierarchy in scalar VEVs. The singlet scalars also acquire weak-scale VEVs. Together with the VLQs, they act as messengers between different generations of quarks in the SM. These messenger particles are responsible for generating the elements of the Cabibbo-Kobayashi-Masakawa (CKM) matrix which depend on the ratios of the singlet VEVs and VLQ masses. Constructed this way, the CKM matrix is found to be $\textit{independent}$ of the SM fermion masses. Using the measured values of the CKM matrix elements and assuming order-one couplings, we derive constraints on the masses of the VLQs and discuss prospects for probing our model in the near future.

Bhubanjyoti Bhattacharya

Suneth Jayawardana

Nausheen Shah

The deconstruction of flavor in the privately democratic Higgs sector