We investigate thermodynamics of a non-interacting quantum field in a static black hole background. The horizon divergences are regulated by the brick wall method, which consists of subjecting the quantum field to Dirichlet boundary conditions on a surface (the brick wall) just outside the horizon. Using heat kernel and Mellin transform methods, we derive high-temperature expansions for the free energy and entropy and study the boundary and higher-order geometric effects on the horizon divergences induced by the brick wall. We consider real scalar, complex scalar, and Dirac fields in Schwarzschild, Reissner–Nordström and dilatonic black hole backgrounds, as well as in their near-horizon geometries. By evaluating the high-temperature expansion of the entropy (up to a certain order) at the Hawking temperature, we show that, for a given field type, the leading horizon divergence is the same for all the metrics considered. Moreover, we show that the different orders in the high-temperature expansion become comparable at the Hawking temperature and compare our findings with existing results in the literature. We derive an explicit formula for the sub-leading horizon divergence expressed in terms of the field mass, surface gravity, horizon area, and dilaton parameter, which is applicable to all the exact metrics considered. We also consider the possibility of using Neumann boundary conditions to regularize the horizon divergences.

Türkiye

Emine Ertuğrul

Birses Debir

Levent Akant

Boundary effects on the thermodynamics of quantum fields near a static black hole

In this work I study the finite temperature Casimir effect caused by a complex and massive scalar field that breaks Lorentz invariance in a CPT-even, aether-like manner. The Lorentz invariance breaking is caused by a constant space-like vector directly coupled to higher order field derivatives. This vector needs to be space-like in order to avoid non-causality problems that will arise with a time-like vector. I investigate the two scenarios of the scalar field satisfying either Dirichlet or mixed boundary conditions on a pair of flat parallel plates. I use the generalized zeta function technique that enables me to obtain the Helmholtz free energy and the Casimir pressure when the Casimir plates are in thermal equilibrium with a heat reservoir at finite temperature. I investigate two different directions of the unit vector, parallel and perpendicular to the plates. I examine both scenarios for both types of boundary conditions and, in both cases and for the two different boundary conditions, I obtain simple analytic expressions of the Casimir energy and pressure in the three asymptotic limits of small plate distance, high temperature, and large mass, examining all combinations of boundary conditions, unit vector direction, and asymptotic limits.

United States

Andrea Erdas

Finite temperature Casimir effect of a Lorentz-violating scalar with higher order derivatives

We point out that events with 6 or more top quarks may be observed at the LHC if certain particles exist at the TeV scale. In a model where a vectorlike quark of charge 2/3 decays into a top quark and a pseudoscalar particle, which subsequently decays into a top-antitop pair, the LHC production cross section for events with 6 top quarks may be above 10 fb. If the pseudoscalar is part of a complex scalar field, then longer cascade decays, involving the scalar partner, may lead to events with 8 or even 10 top quarks. We show that for a region of parameter space the dominant LHC signal in this model is 8 top quarks (i.e., four $$ t\overline{t} $$ pairs). The ensuing signals would be spectacular, including many leptons and $\textit{b}$ jets. A discovery in that case would allow several cross section measurements that may determine the masses of all three new particles.

Elias Bernreuther

Bogdan Dobrescu

Multi-top signals of vectorlike quarks at the LHC

We present a prescription for computing tree-level scattering amplitudes in 10D super-Yang-Mills (SYM) theory using the pure spinor worldline formalism. The pure spinor formalism has proven to be a powerful framework for studying supersymmetric field theories, providing manifestly covariant and BRST-invariant formulations of amplitudes. By incorporating the worldline approach, we construct a first-quantized representation of SYM amplitudes in 10D, where interactions are encoded through the insertion of vertex operators along the particle’s trajectory. We explicitly compute the N-point function, demonstrating an agreement with the $\textit{α}$ $\textit{→}$ 0 limit of open superstring amplitudes and confirming that the kinematic numerators satisfy the expected BRST relations. Our results establish the pure spinor worldline formalism as a tool for studying scattering amplitudes and suggest further applications to 11D supergravity.

Sweden

Brazil

Max Guillen

Marcelo Santos

United Kingdom

Spain

Eggon Viana

The pure spinor superparticle and 10D super-Yang-Mills amplitudes

We perform a detailed pseudodata study to estimate the expected theory uncertainty in the extraction of the strong coupling constant, $\textit{α}$ ($\textit{m}$ ), from a fit to the measured Drell-Yan transverse momentum ($\textit{q}$ ) spectrum at small $\textit{q}$ ≪ $\textit{m}$ . We consider two approaches to estimate the dominant perturbative uncertainties. We first discuss that the traditional approach based on varying unphysical scales is insufficient here because it cannot correctly account for bin-by-bin theory correlations in the $\textit{q}$ spectrum, which are critically important in this case. We then use this case as a nontrivial application of a new approach based on theory nuisance parameters (TNPs), which encodes the correct theory correlations by construction. Moreover, the TNPs can be profiled in the fit thereby allowing the data to constrain the theory uncertainties in a consistent manner. We furthermore discuss the interplay with nonperturbative effects in the peak region $\textit{q}$ ≲ 10 GeV, from where most of the $\textit{α}$ sensitivity originates. The associated nonperturbative uncertainties on $\textit{α}$ when fitting only the $\textit{q}$ spectrum are large. They can in principle be reduced by including additional constraints on the nonperturbative Collins-Soper kernel from lattice QCD calculations. We find that these improvements in the treatment of perturbative and nonperturbative uncertainties and their correlations will enable a competitive $\textit{α}$ extraction from Drell-Yan data at small $\textit{q}$ . We also discuss the implications of our findings, calling into question a recent $\textit{α}$ extraction from the $\textit{Z q}$ spectrum by the ATLAS experiment.

Belgium

Thomas Cridge

Germany

Giulia Marinelli

Frank Tackmann

Theory uncertainties in the extraction of $\textit{α}$

An open question in AdS/CFT is how to reconstruct semiclassical bulk operators precisely enough that non-perturbative quantum effects can be computed. We propose a set of physically-motivated requirements for such a reconstruction map, and explicitly construct a map satisfying these requirements in Jackiw-Teitelboim (JT) gravity. Our map is found by canonically quantizing “action-angle” variables for JT gravity, which are chosen to ensure that the spectrum of the fundamental quantum theory matches known results from the gravitational path integral. We then study unitary quantum dynamics in this theory, and obtain analytical predictions for the dynamics of the wormhole length, including its quantum fluctuations, leveraging techniques from quantum ergodicity theory. Level repulsion in the non-perturbative JT spectrum implies that the average wormhole length is non-monotonic in time, that fluctuations in wormhole length are non-perturbatively suppressed until nearly the Heisenberg time, and that the late-time-evolved Hartle-Hawking state has a heavy-tailed distribution of lengths. We discuss the implications of our results for the “complexity = volume” conjecture.

Chris Akers

Andrew Lucas

Amit Vikram

On the reconstruction map in JT gravity

We compare the fixed-order NLO QCD predictions for the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>p</mi><mi>p</mi><mo stretchy="false">→</mo><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mo>+</mo><mi>X</mi></math> process in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>4</mn><mo>ℓ</mo></math> decay channel with the parton-shower-based results obtained with the powheg and mc@nlo matching methods. In the first case, NLO QCD corrections are consistently included in both the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover><mi>t</mi><mover accent="true"><mi>t</mi><mo stretchy="false">¯</mo></mover></math> production step and the decays of the four top quarks, preserving all spin correlations. In the second approach, higher-order effects in top-quark decays with approximate spin correlations are simulated in the pythia parton-shower framework. Additionally, we analyze the impact of including the so-called matrix element corrections in top-quark decays in both parton-shower matched predictions. The comparison is performed at the integrated and differential fiducial cross-section level for the LHC center-of-mass energy of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msqrt><mi>s</mi></msqrt><mo>=</mo><mn>13.6</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math>.

Manal Alsairafi

Nikolaos Dimitrakopoulos

Malgorzata Worek

Modeling top-quark decays in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mi>t</mi><mover accent="true"><mrow><mi>t</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover><mi>t</mi><mover accent="true"><mrow><mi>t</mi></mrow><mrow><mo stretchy="false">¯</mo></mrow></mover></mrow></math> production at the LHC

In the present work, we perform a combined analysis of the cross sections for $$e^+ e^- \rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0$$ by including the interference between direct coupling process and resonance intermediate process. When setting the isospin factor as a free parameter, we can well reproduce the structures in the cross sections for $$e^+ e^- \rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0,$$ however, the isospin factor deviates with the isospin symmetry conservation predicted value of one. By fixing the isospin factor to be one, we find the cross sections for $$e^+ e^-\rightarrow K^+ K^-$$ can be accurately fitted, while the same model parameters fail to adequately reproduce the observed cross section for the process $$e^+ e^- \rightarrow K_S^0 K_L^0,$$ which indicate that there should be contributions from other vector meson states, such as $$\rho (2150)$$ and $$\omega (2220).$$ The combined analysis with $$\phi (2170),$$ $$\omega (2220)$$ and $$\rho (2150)$$ indicate that the inclusion of $$\rho (2150)$$ can improve the descriptions of the cross sections for $$e^+ e^-\rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0.$$

China

Dian-Yong Chen

Jing Liu

Yu Bai

Chun-Hua Liu

Wen-Biao Yan

Zhao-Xia Meng

A combined analysis of $\textit{Y}$(2240) in the $$e^+ e^- \rightarrow K^+ K^-$$ and $$e^+ e^- \rightarrow K_S^0 K_L^0$$ processes

We formulate a light-front model for the pion that explicitly incorporates the gluonic degree of freedom. In this framework, high-energy scattering off the pion is described by an active gluon, while the remaining constituents are treated as a spectator system with an effective mass. The mass spectrum and light-front wave functions (LFWFs) of the pion are determined by solving two Schrödinger-like equations derived from quantum chromodynamics: the light-front holographic equation in the chiral limit and the ’t Hooft equation. Using the resulting LFWFs, we compute the gluon distributions within pion, including the parton distribution functions in comparison with the available global fits, generalized parton distributions, and transverse momentum-dependent distributions. The present analysis is restricted to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi domain of the pion’s gluon generalized parton distribution, without explicit construction of the Efremov-Radyushkin-Brodsky-Lepage region. Consequently, the polynomiality condition for full Mellin moments is not satisfied by construction. Furthermore, we demonstrate that the obtained LFWFs provide a good description of the gravitational form factors of pion when compared with the recent lattice QCD results.

Satvir Kaur

Chandan Mondal

Gluon distributions in the pion

It is well-known that future timelike infinity ($\textit{i}$ ) in four-dimensional Minkowski spacetime is conformal to the unit three-dimensional hyperboloid ($\textit{H}$ ). We asymptotically expand massive fields with spin 0$\textit{,}$ 1$\textit{,}$ 2 near $\textit{i}$ and extrapolate them onto this hyperboloid. These fields oscillate with a frequency equal to their mass and exhibit a universal asymptotic decay $\textit{τ}$ . The fundamental fields are free and encode the outgoing scattering data. They are local operators defined on the boundary $\textit{H}$ with which we construct the Poincaré charges. The Poincaré algebra can be extended to MDiff($\textit{H}$ ) ⋉ $\textit{C}$ ($\textit{H}$ ) using smeared operators associated with energy and angular momentum densities. For spinning fields, a spin operator must be included to close the algebra. The extended algebra shares the same form as the five-dimensional intertwined Carrollian diffeomorphism and reduces to the BMS algebra at $\textit{i}$ by restricting the choice of test functions and vectors.

Wen-Bin Liu

Jiang Long

Extrapolating the massive fields to future timelike infinity