In supergravity, charged rotating black holes are generically driven towards becoming extremal and supersymmetric through the emission of Hawking radiation. Eventually, as the black hole approaches the BPS bound and is close to becoming supersymmetric, quantum gravity corrections become critical to describing the emission of Hawking radiation, making the QFT in curved spacetime approximation inaccurate. In this paper, we compute how such quantum gravity corrections affect the spectrum of Hawking radiation for black holes in $$ \mathcal{N} $$ = 2 supergravity in flatspace. We show that due to such corrections, the spectrum of emitted Hawking radiation for both spin-0 and spin-1/2 particles deviates drastically at low temperatures from the naively expected black-body spectrum. Rather remarkably, the spectrum exhibits a discrete emission line from direct transitions from near-BPS to BPS states, providing the first controlled example where the discreteness of the black hole energies is visible in the emitted Hawking radiation. Similar quantum gravity effects drastically modify the absorption cross-section: BPS black holes are transparent to certain frequencies, while near-BPS black holes appear much larger than the semi-classical prediction.

United States

Guanda Lin

Luca Iliesiu

Mykhaylo Usatyuk

The evaporation of black holes in supergravity

We study periods of multi-parameter families of K3 surfaces, which are relevant to compute the maximal cuts of certain classes of Feynman integrals. We focus on their automorphic properties, and we show that generically the periods define orthogonal modular forms. Using accidental isomorphisms between Lie groups of small rank, we show how one can use the intersection product on the periods to identify K3 surfaces whose periods can be expressed in terms of other classes of modular forms that have been studied in the mathematics literature. We apply our results to maximal cuts of three-loop banana integrals, and we show that depending on the mass configuration, the maximal cuts define ordinary modular forms or Hilbert, Siegel or hermitian modular forms.

Germany

Claude Duhr

Modular forms for three-loop banana integrals

This work revisits the Euclidean Dynamical Triangulation (DT) approach to non-perturbative quantum gravity in three dimensions. Inspired by a recent combinatorial study [1] of a subclass of 3-sphere triangulations constructed from trees, called the $\textit{triple-tree}$ class, we present a Monte Carlo investigation of DT decorated with a pair of spanning trees, one spanning the vertices and the other the tetrahedra of the triangulation. The complement of the pair of trees in the triangulation can be viewed as a bipartite graph, called the $\textit{middle graph}$ of the triangulation. In the triple-tree class, the middle graph is restricted to be a tree, and numerical simulations have displayed a qualitatively different phase structure compared to standard DT. Relaxing this restriction, the middle graph comes with two natural invariants, namely the number of connected components and loops. Introducing corresponding coupling constants in the action, allows one to interpolate between the triple-tree class and unrestricted tree-decorated DT. Simulations of this extended model confirm the existence of a new phase, referred to as the $\textit{triple-tree phase}$, besides the familiar crumpled and branched polymer phases of DT. A statistical analysis of the phase transitions is presented, showing hints that the branched polymer to triple-tree phase transition is continuous.

Netherlands

Timothy Budd

Dániel Németh

Phases of tree-decorated Dynamical Triangulations in 3D

Motivated by SYK-like models describing near-BPS black holes in string/M-theory, we consider gauging the U(1) symmetry of the complex SYK model in the presence of a Wilson line with charge $\textit{k}$. At a fixed background gauge field, solutions to the Schwinger-Dyson equations display vastly different properties from those at a fixed real chemical potential. In the partition function and the two-point function, the integral over the gauge field is performed either directly or via a large $\textit{N}$ saddle point approximation, and both results are consistent with exact diagonalization data. From the behaviour of the two-point function at large $\textit{N}$, we deduce that the conformal symmetry at low energies is preserved at fixed $\textit{κ}$ = $\textit{k}$/$\textit{N}$ = 0, but broken at $\textit{κ}$ ≠ 0. In addition, we find that there is maximal chaos for all $\textit{k}$.

China

Ziruo Zhang

Cheng Peng

Gauging the complex SYK model

The physics of quarkonium created in heavy-ion collisions is intrinsically connected to the correlation functions of adjoint chromoelectric fields in quantum chromodynamics. We study such correlation functions in a weak-coupling expansion in a thermal medium. We identify three distinct gauge-invariant correlators, and evaluate them to next-to-leading order. Two of the resulting correlators turn out to be asymmetric. We pinpoint the source of this asymmetry to Matsubara zero modes associated with Wilson lines. The results are shown to agree well with recent lattice calculations at high temperatures.

Nora Brambilla

Panayiotis Panayiotou

Spain

Saga Säppi

Antonio Vairo

The chromoelectric adjoint correlators in Euclidean space at next-to-leading order

It is well-known that the back-to-back (correlation) limit of inclusive quark-antiquark dijet production in unpolarized high energy electron-proton collisions can probe the Weizsäcker-Williams (WW) gluon transverse momentum-dependent distribution (TMD) at small $\textit{x}$ [1, 2]. In this paper, we consider a helicity-dependent version of the same process: we study the double-spin asymmetry for inclusive quark-antiquark dijet production in longitudinally polarized electron-proton scattering at high energies. We show that in the back-to-back limit this process probes the WW gluon $\textit{helicity}$ TMD. Furthermore, we derive the small-$\textit{x}$ evolution equation for the operator related to the WW gluon helicity distribution. We find that in the double-logarithmic approximation and in the large-$\textit{N}$ limit, the small-$\textit{x}$ asymptotics of the WW gluon helicity distribution is governed by exactly the same evolution equation as that for the $\textit{dipole}$ gluon helicity distribution. The longitudinal double-spin asymmetry for inclusive dijet production in the longitudinally polarized electron-proton collisions can thus test the small-$\textit{x}$ helicity evolution equations and facilitate constraining the initial conditions for phenomenology based on these equations.

Yuri Kovchegov

Ming Li

Weizsäcker-Williams gluon helicity distribution and inclusive dijet production in longitudinally polarized electron-proton collisions

We obtain novel constraints on new scalar fields interacting with Standard Model fermions through Lorentz-violating couplings, bridging searches for scalar particles and Lorentz-symmetry tests. These constraints arise from torsion-balance experiments, magnetometer searches, and an excessive energy loss in Red Giant stars. Torsion-balance experiments impose stringent constraints, benefitting from large macroscopic sources including the Sun and Earth. Magnetometer-based searches, which detect pseudo-magnetic fields through spin precession, offer additional limiting power to low-mass scalar fields. Meanwhile, observations of Red Giant stars place strong limits on additional energy loss mechanisms, extending these constraints to higher scalar mass ranges and a wider range of Lorentz-violating couplings. Combining data from laboratory experiments and astrophysical observations, this approach strengthens constraints on Lorentz-violating interactions and paves the way for future investigations into physics beyond the Standard Model.

Sweden

P. Carenza

J. Jaeckel

G. Lucente

Italy

T. Poddar

United Kingdom

N. Sherrill

M. Spannowsky

Limits on new Lorentz-violating bosons

We revisit the expected sensitivity of large-scale xenon detectors to Weakly Interacting Massive Particles (WIMPs). Assuming current primary noise sources can be mitigated, we find that with the present discrimination power between nuclear and electron recoils, the experimental sensitivity is limited not only by atmospheric neutrinos’ nuclear recoils (“nuclear recoil neutrino fog”) but also by solar neutrinos’ electron-recoil events (“electron recoil neutrino fog”). While this is known by experimentalists, it is often missed or misunderstood by theorists, and we therefore emphasize this effect. We set up a realistic detector simulation to quantify the contamination of the WIMP signal from both these neutrino backgrounds. We observe that the electron-recoil background remains significant even for signal rates exceeding those of atmospheric neutrinos, as predicted by most electroweak WIMP candidates. We update the projections for the required exposure to exclude/discover a given electroweak WIMP, streamlining the computation of their signal rates and uncertainties. We show that all of the real WIMPs with zero hypercharge can be excluded (discovered) with a 50 tonne year (300 tonne year) exposure. A similar exposure will allow to probe a large portion of the viable parameter space for complex WIMP with non-zero hypercharge.

Itay Bloch

Israel

Salvatore Bottaro

Diego Redigolo

France

Ludovico Vittorio

Looking for WIMPs through the neutrino fogs

We consider supersymmetric solutions of $\textit{D}$ = 4, $$ \mathcal{N} $$ = 2 Euclidean gauged supergravity coupled to an arbitrary number of vector multiplets. Such solutions admit an R-symmetry Killing vector, $\textit{ξ}$, constructed as a bilinear in the Killing spinor. The Killing spinor bilinears can also be used to construct polyforms that are equivariantly closed under the action of the equivariant exterior derivative d = d – $\textit{ξ}$⌟ . This allows one to compute various flux integrals and the on-shell action using localization, without solving any supergravity equations, just assuming the supersymmetric solutions exist. The flux integrals allow one to obtain important UV-IR relations, relating fixed point data in the bulk to data on the asymptotic AdS boundary, allowing one to express the gravitational free energy in terms of boundary SCFT data. We illustrate the formalism with a number of examples, including classes of solutions which are unlikely to be ever constructed in closed form.

Switzerland

Pietro Genolini

Jerome Gauntlett

Yusheng Jiao

Alice Lüscher

James Sparks

Equivariant localization for $\textit{D}$ = 4 gauged supergravity

We develop a new off-shell formulation for six-dimensional conformal supergravity obtained by gauging the 6D $$ \mathcal{N} $$ = (2, 0) superconformal algebra in superspace. We provide the complete gauged algebra, which proves to be considerably constrained compared to other conformal superspaces constructed in the past. This formulation is employed to obtain the unique 6D $$ \mathcal{N} $$ = (2, 0) Bach tensor superfield, which describes the multiplet of equations of motions for conformal supergravity, by using a general ansatz fixed by truncation to 6D $$ \mathcal{N} $$ = (1, 0) results. We also translate some results into components for precise matching against the literature.

Australia

Christian Kennedy

Gabriele Tartaglino-Mazzucchelli

Six-dimensional $$ \mathcal{N} $$ = (2, 0) conformal superspace