The characteristics of a thermal system depend strongly on its response to thermal gradients and the underlying microscopic interactions among constituents. In the present study, we investigate the thermodynamic and transport properties of the quark-gluon plasma (QGP) at finite baryon chemical potential within a deep-learning-assisted quasiparticle model. The temperature- (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">T</mi></math>) and baryon chemical-potential- (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi mathvariant="normal">B</mi></msub></math>) dependent thermal masses of quasiparticles are estimated using neural networks trained to reproduce lattice QCD results for the equation of state, obtained via a Taylor-like expansion around vanishing baryon chemical potential. The trained model acts as an effective emulator, enabling us to estimate the thermodynamic and transport properties at finite <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi mathvariant="normal">B</mi></msub></math>. We compute the speed of sound, specific heat, viscosity, and conductivity of the deconfined medium. Our findings are in good agreement with available lattice calculations and other phenomenological models. The present study demonstrates that a deep-neural-network-based approach provides an efficient framework for studying the properties of the QGP at finite baryon density.

India

Rishabh Kumar Tiwari

Kangkan Goswami

Hungary

Suraj Prasad

Captain R. Singh

Raghunath Sahoo

China

Mohammad Yousuf Jamal

Thermodynamic and transport properties of the quark-gluon plasma at finite chemical potential with a deep neural network framework

We calculate the vacuum polarization energy (VPE) of a scalar field in the background of a nonsingular cosmic string in <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>2</mn><mo>+</mo><mn>1</mn></math> spacetime dimensions. Our calculation expresses the VPE as a renormalized sum and integral over scattering data, which can be expressed in terms of Legendre and Bessel functions for the “ballpoint pen” model, analogous to a square well in curvature, and which can be obtained numerically for a generic string profile. We show how relationships between the local density of states, expressed in terms of the Green’s function, and the global density of states, expressed in terms of the Jost function, extend to this curved spacetime background and allow for precise implementation of perturbative renormalization conditions.

United States

N. Graham

South Africa

H. Weigel

Vacuum polarization energy of a nonzero radius cosmic string induced spacetime

The double-logarithmic series of non-relativistic $\textit{B}$ → $\textit{η}$ form factors at large recoil is governed by a coupled set of integral equations, reflecting an intricate interplay between arbitrarily many soft-quark and soft-gluon exchanges. Whereas we previously derived these integral equations with diagrammatic resummation techniques, we analyze the form factors with methods from Soft-Collinear Effective Theory (SCET) in this work. Although the resulting factorization theorem for the so-called soft-overlap contribution is known to be spoilt by endpoint divergences, it can still be used at the level of bare (regularized) quantities at any fixed order in perturbation theory. By calculating the required ingredients, we show that the SCET analysis confirms the predictions of the integral equations up to three-loop order. We also argue that the iterative structure and the intertwined soft-quark and soft-gluon effects can be derived from standard renormalization-group equations of the $\textit{B}$ -meson light-cone distribution amplitudes, provided their inverse moments are regularized with an appropriate cutoff.

Germany

Guido Bell

Switzerland

Philipp Böer

Thorsten Feldmann

Dennis Horstmann

Vladyslav Shtabovenko

$\textit{B}$ $\textit{c}$ $\textit{ → η}$ $\textit{c}$ form factors at large recoil: SCET analysis and a three-loop consistency check

An enhancement in the three-pion energy at around $$ \sqrt{s} $$ ≈ 1.42 GeV with $\textit{a}$ quantum numbers was observed at the COMPASS experiment. This was later attributed to the triangle singularity mechanism involving an on-shell $\textit{K}$ (892), $\textit{K}$ and $$ \overline{K} $$ intermediate states. The alignment of the decay $\textit{K}$ with the spectator $$ \overline{K} $$ produces an $\textit{f}$ (980), resulting in a kinematic enhancement, which is classically explained by the Landau equations. However, this one-loop process forms only part of a non-diagonal transition in a much larger coupled-channel framework. This study demonstrates the feasibility of embedding one-loop triangle-singularity calculations into a unitary three-body amplitude allowing one to consistently incorporate final-state interactions and their potentially substantial effect. For this, up to $\textit{P}$ -wave isobars and all sub-channel isospins are combined in a nine-channel production amplitude that is fitted to COMPASS lineshapes at different momentum transfers. The fitted amplitude reproduces the narrow enhancement in the ($\textit{πf}$ ) channel near $$ \sqrt{s} $$ ≈ 1$\textit{.}$42 GeV. This implies that the triangle singularity mechanism sufficiently explains the observed enhancement, and an additional genuine $\textit{a}$ (1420) pole is not required. Incidentally, the parameters of the ground state axial vector resonance (the $\textit{a}$ (1260)) are also extracted from that data.

Ajay Sakthivasan

Yuchuan Feng

Michael Döring

Maxim Mai

The $\textit{a}$ 1(1420) in a unitary coupled-channel three-body approach

We study the sensitivity of a high-energy $\textit{μ}$–collider with center of mass energy in the multi–TeV range in testing electroweak dipole interactions of the $\textit{b}$-quark. We parametrize the relevant deformations in the language of the Standard Model effective field theory, where the dominant modifications arise at the $\textit{d}$ = 6 level. We analyse $$ {\mu}^{+}{\mu}^{-}\to b\overline{b} $$ and $$ {\mu}^{+}{\mu}^{-}\to b\overline{b}h $$ scatterings, performing a study at the level of a fast detector simulation. Owing the chiral structure of the dipole interaction, the study of the $$ {\mu}^{+}{\mu}^{-}\to b\overline{b}h $$ process allows to enforce the stronger bounds on the Wilson coefficients of the $\textit{d}$ = 6 operators. The limits that can be obtained surpass present and future bounds from EW precision measurements also improving upon the ones arising from the measurement of the ∆$\textit{F}$ = 1 transitions $\textit{B}$ → $\textit{X}$ $\textit{γ}$.

Italy

Daniele Barducci

Bottom quark electroweak dipole moments at a high-energy $\textit{μ}$−collider

This MINERvA analysis is the first neutrino and antineutrino study of a shallow inelastic scattering region, which is the transition region between resonant production and deep inelastic scattering processes. This transition is explicitly included in this study by expanding the scope of shallow inelastic scattering to include not only the mainly lower-<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Q</mi><mn>2</mn></msup></math> nonresonant pion production but also the kinematic region where pion production off quarks within the nucleon become significant with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Q</mi><mn>2</mn></msup></math> below the onset of the deep-inelastic scattering region defined in this analysis. To reduce the resonance background the kinematic region <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>1.5</mn><mo>&lt;</mo><mi>W</mi><mo>&lt;</mo><mn>2</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> was chosen. In addition to the inclusive differential cross section measurements in this <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>W</mi></math> region, a sample with <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Q</mi><mn>2</mn></msup><mo>≥</mo><mn>1</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi><mo>/</mo><msup><mi>c</mi><mn>2</mn></msup></math> was also analyzed to emphasize shallow inelastic scattering interactions off quarks within the nucleon. The measurements of one-dimensional cross sections at <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mo stretchy="false">⟨</mo><msub><mi>E</mi><mi>ν</mi></msub><mo stretchy="false">⟩</mo></mrow><mo>∼</mo><mn>6</mn><mtext> </mtext><mtext> </mtext><mi>GeV</mi></math> on hydrocarbon of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>Q</mi><mn>2</mn></msup></math>, Bjorken x, and muon momentum variables are compared with modified predictions from the genie 2 neutrino generator as well as predictions of other neutrino simulators gibuu, neut, nuwro and an alternative genie 3 version. Significant discrepancies both in shape and magnitude between measurements and neutrino simulator predictions of all variables have been observed.

Brazil

A. Lozano

G. Silva

G. Caceres

S. Akhter

Z. Ahmad Dar

V. Ansari

M.V. Ascencio

M. Sajjad Athar

Mexico

J.L. Bonilla

A. Bravar

G.A. Díaz

H. da Motta

J. Felix

L. Fields

R. Fine

A.M. Gago

H. Gallagher

P.K. Gaur

R. Gran

E. Granados

Canada

D.A. Harris

J. Kleykamp

United Kingdom

A. Klustová

M. Kordosky

D. Last

X.G. Lu

S. Manly

W.A. Mann

C. Mauger

K.S. McFarland

B. Messerly

O. Moreno

J.G. Morfín

J.K. Nelson

C. Nguyen

A. Olivier

V. Paolone

G.N. Perdue

C. Pernas

K.J. Plows

M.A. Ramírez

D. Ruterbories

H. Schellman

C.J. Solano Salinas

D.S. Correia

M. Sultana

V.S. Syrotenko

A.V. Waldron

Chile

B. Yaeggy

Measurement of charged-current <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>ν</mi><mi>μ</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mover accent="true"><mi>ν</mi><mo stretchy="false">¯</mo></mover><mi>μ</mi></msub></math> cross sections on hydrocarbon in a shallow inelastic scattering region

We address pion transitions involving heavy quarkonium and heavy exotic states in the Born-Oppenheimer effective field theory. Many of these states have a size similar or larger than the typical hadronic scale, and hence the usual QCD multipole expansion breaks down. Unknown low energy functions must be introduced, which at short distances must reproduce the known results of the multipole expansion. In order to determine the long distance behavior of these functions, we propose an interaction Lagrangian for pions and the QCD string. By matching the amplitudes obtained with this Lagrangian to the ones of the Born-Oppenheimer effective field theory in the static limit, we obtain the low energy functions in terms of three universal parameters. As a by-product, we also obtain the light quark mass dependence of the string tension. Assuming that the low energy functions are long-distance dominated, we calculate several quarkonium-to-quarkonium and hybrid-to-quarkonium transitions. We estimate the universal constants and provide a phenomenological analysis of the most relevant transitions.

Spain

Joan Soto

Sandra Tomàs Valls

Pion transitions in the Born-Oppenheimer effective field theory: A long distance approach

The shape function and the light-cone distribution amplitude of the heavy meson jointly characterize the nonperturbative structure of the heavy meson on the light cone, with the former being essential for theoretical predictions of inclusive decays and the latter for exclusive decays. While first-principles lattice QCD results for the heavy meson LCDA have become available in recent years, lattice results for the shape function remain absent. In this work, we establish a two-step factorization scheme—known as the HQLaMET framework—for computing the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math>-meson shape function on the lattice, which separates the three scales <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msubsup><mi>P</mi><mi>B</mi><mi>z</mi></msubsup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>m</mi><mi>b</mi></msub></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi mathvariant="normal">Λ</mi><mi>QCD</mi></msub></math> at leading power. For illustration, starting from a phenomenological model for the shape function in HQET, we provide a graphical presentation of the entire procedure of this framework. The results of the current work lay the foundation for nonperturbative lattice QCD determinations of the shape function in the near future.

Ao-Sheng Xiong

Jun Ding

Ji Xu

Jun Zeng

Shuai Zhao

Accessing the HQET <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>B</mi></math>-meson shape function from a large-momentum effective theory quasishape function

The observed fluid behavior of the matter produced in heavy ion and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi></mrow></math> collisions implies that the strings stretched between the constituents of the projectile and target should have a hard core giving rise to a repulsion between them. It is shown that in these collisions there are two critical string densities, one corresponding to the well-studied percolation of strings and another to the percolation of the hard core of the strings. These two critical densities are related to two critical temperatures, one <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>T</mi><mspace width="4pt"></mspace><mo>≈</mo><mspace width="4pt"></mspace><mn>160</mn></mrow></math> MeV would correspond to the restoration of chiral symmetry and partial deconfinement and a second transition <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>T</mi><mspace width="4pt"></mspace><mo>≈</mo><mspace width="4pt"></mspace><mn>220</mn></mrow></math> MeV form the fluid behavior of quantum chromodynamics matter strongly interacting to a quasi free gas of quarks and gluons. This argument is supported by the recently published results on the sudden increase in the degrees of freedom above the deconfinement temperature in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>p</mi><mi>p</mi></mrow></math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>A</mi><mtext>−</mtext><mi>A</mi></mrow></math> collisions [Mishra et al., <a href="http://dx.doi.org/10.1016/j.nuclphysa.2024.122865">Nucl. Phys. A 1046, 122865 (2024)</a>].

C. Pajares

R.P. Scharenberg

B.K. Srivastava

Existence of a second phase transition in <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>A</mi><mtext>−</mtext><mi>A</mi></mrow></math> collisions at energies available at the CERN Large Hadron Collider: A physical interpretation

We propose a relativistic quantum battery model consisting of an accelerated Unruh–DeWitt detector coupled to a massless scalar field in a de Sitter and anti-de Sitter spacetimes. The maximal amount of quantum extractable work, defined as the ergotropy, is used to probe Unruh–Hawking thermality induced by acceleration and spacetime curvature. Using the open quantum system approach, we study the dynamics of the ergotropy with respect to the Kubo–Martin–Schwinger temperature, spacetime boundary conditions, and dimensionality. It has been found that the asymptotic value of quantum work extraction is determined solely by the acceleration and curvature. The steady behavior in the two spacetimes can be unified to witness the Unruh–Hawking thermality which is independent of boundary conditions and dimensionality. From a perspective of time-dependent evolution, we investigate how the ergotropy evolves through different pathways as the battery gradually reaches the same thermal equilibrium state characterized by a certain KMS temperature. In dS spacetime, the evolution at large acceleration exhibits pronounced oscillations and differs from the fast thermal relaxation observed at low acceleration. Varying the boundary condition in AdS can improve the energy storage of the moving battery. When the dimension of AdS is increased, vacuum fluctuations can modestly amplify the ergotropy in the initial stage and facilitate the rapid thermalization. From the perspective of energy transfer, the relativistic quantum battery helps explore the thermal vacuum in curved spacetimes.

Xiang Hao

Tao-Feng Gan

Cheng-Tai Wu

Tian-Xi Ren

Wei-Wei Zhang

Yin-Zhong Wu

Quantum thermodynamics of ergotopy for a relativistic battery as a witness to Unruh–Hawking thermality in curved (A)dS spacetimes