We study the chiral condensate at finite temperature in AdS/QCD in a time-dependent background, in which the position of the black hole horizon <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>z</mi></mrow><mrow><mi>h</mi></mrow></msub></mrow></math> changes with time, producing an increasing or decreasing temperature. Conformal invariance is broken, as in the soft-wall model, by a static quadratic dilaton. Two different scenarios are analyzed; in the first a general power-law time dependence is assumed for <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>z</mi><mi>h</mi></msub></math>, while in the second the energy-momentum tensor at late times reproduces the one found in viscous hydrodynamics. Depending on the rate at which the system evolves, the transition shifts toward lower temperatures. If the chiral condensate is far from equilibrium at low temperatures, oscillations around its equilibrium value are observed before thermalization. A prethermalization stage is found in the chiral limit if the initial condition is set at a temperature close to the critical one. In the hydrodynamic setup the evolution of the medium is slow enough, and the chiral condensate soon matches the equilibrium curve.

Italy

Floriana Giannuzzi

Stefano Nicotri

Out-of-equilibrium chiral condensate in AdS/QCD

We present the first global analysis of fragmentation functions for light charged hadrons (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>π</mi><mo>±</mo></msup></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>K</mi><mo>±</mo></msup></math>) at full next-to-next-to-leading order in quantum chromodynamics, incorporating world data from both single-inclusive electron-positron annihilation and semi-inclusive deep-inelastic scattering. The collinear factorization has been tested with low-momentum-transfer data and has demonstrated success at high hadron momenta. Additionally, we study the impact of current global data on hadron production to the parton distribution functions (PDFs), and find they favor a reduced asymmetry in the strange (anti)quark PDFs, as compared to the asymmetry predicted by state-of-the-art PDFs derived from inclusive data.

China

Jun Gao

XiaoMin Shen

Hongxi Xing

Yuxiang Zhao

Bin Zhou

Fragmentation Functions of Charged Hadrons at Next-to-Next-to-Leading Order and Constraints on the Proton Parton Distribution Functions

The analysis of RHIC hydrogen gas jet target polarimeter measurements of transverse analyzing powers <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>A</mi><mi mathvariant="normal">N</mi></msub><mo stretchy="false">(</mo><mi>t</mi><mo stretchy="false">)</mo></math> in proton-nucleus scattering requires accurate Coulomb corrections to both spin-flip and nonflip amplitudes. These corrections must cover a wide range of nuclear charges <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>Z</mi></math> and form factor slopes, with flexibility to vary form factors during data fitting. To avoid technically challenging calculations involving a small but finite fictitious photon mass, the Coulomb correction to the nonflip electromagnetic amplitude with an exponential form factor was related to the corresponding correction for the spin-flip amplitude. This approach allows soft photon contributions to all amplitudes, including those with nonexponential form factors, to be calculated in the massless photon limit using only analytical expressions and numerically stable integrals with nonsingular integrands and finite integration limits. In addition, an absorptive correction to the spin-flip electromagnetic amplitude, which plays a critical role in spin effects in forward polarized proton-nucleus scattering, was accurately evaluated.

United States

A.A. Poblaguev

Numerical calculation of Coulomb corrections in forward elastic <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>p</mi><mo stretchy="false">↑</mo></msup><mi>p</mi></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>p</mi></mrow><mrow><mo stretchy="false">↑</mo></mrow></msup><mi>A</mi></mrow></math> scattering

We investigate the dynamics of spinning test particles orbiting static black holes in effective quantum gravity (EQG) using the Mathisson–Papapetrou–Dixon (MPD) formalism with two distinct models. The purpose of using two models is to compare qualitatively different realizations of EQG corrections and assess their impact on spin-gravity coupling and orbital behavior. Through analysis of the effective potential, we demonstrate how $$\zeta $$ and particle spin $\textit{s}$ jointly influence orbital stability, revealing that (i) in Model-1, increasing $$\zeta $$ elevates the potential barrier while spin effects become dominant near the horizon, (ii) Model-2 shows weaker dependence on $$\zeta $$ except for high-spin configurations. The innermost stable circular orbits (ISCOs) exhibit characteristic scaling $$r_{\text {ISCO}}(\zeta ,s)$$ , with quantum corrections that increase the radius of the ISCO by up to 27% relative to Schwarzschild for $$\zeta =4$$ in Model-1. We derive critical spin values $$s_{\text {max}}$$ beyond which particle trajectories become spacelike, finding $$s_{\text {max}}$$ decreases monotonically with $$\zeta $$ in Model-2 but shows non-monotonic behaviour in Model-1. The particle collision energetics are analyzed, showing that the center-of-mass energies $$E_{\text {cm}}$$ can be enhanced by spin-parameter tuning, reaching $$E_{\text {cm}}/2m \sim 8$$ for $$(\zeta ,s_1,s_2)=(4,-0.5,0.5)$$ near the horizon. Trajectory simulations reveal that quantum corrections in Model-1 induce precession effects absent in Model-2, suggesting observational signatures to distinguish EQG models. Our results establish the combined influence of quantum spacetime structure and spin-curvature coupling on the test particle dynamics, with implications for EQG phenomenology and gravitational wave astronomy.

Uzbekistan

Dilmurod Umarov

Azerbaijan

Farruh Atamurotov

South Africa

India

Sushant Ghosh

Ahmadjon Abdujabbarov

G. Mustafa

Dynamics of spinning particles around static black holes in effective quantum gravity

We present the second part of a systematic calculation of the two-loop anomalous dimensions for the low-energy effective field theory below the electroweak scale (LEFT): the baryon-number-violating sector at dimension six in the power counting. We obtain the results in two different schemes: in the algebraically consistent ’t Hooft-Veltman scheme for $\textit{γ}$ , corrected for evanescent as well as chiral-symmetry-breaking effects through finite renormalizations; and in naive dimensional regularization, which in the considered sector of the theory does not lead to any ill-defined $\textit{γ}$ -odd traces. Our results are of interest for a reanalysis of the constraints on physics beyond the Standard Model from proton-decay searches within an EFT framework at next-to-leading-logarithmic accuracy.

Switzerland

Luca Naterop

Peter Stoffer

Renormalization-group equations of the LEFT at two loops: dimension-six baryon-number-violating operators

We study the <math altimg='si1.svg'><mi>S</mi><mi>O</mi><mo stretchy='false'>(</mo><mn>2</mn><mo stretchy='false'>)</mo><mo>&#215;</mo><mi>S</mi><mi>U</mi><mo stretchy='false'>(</mo><mi>N</mi><mo linebreak='badbreak' linebreakstyle='after'>=</mo><mn>2</mn><mo stretchy='false'>)</mo></math> invariant matrix models corresponding to the regularised description of the quantum bosonic membrane in <math altimg='si2.svg'><mi>D</mi><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>4</mn></math> dimensional spacetime. The lowest energy levels and the wave function of the ground state are computed numerically with satisfactory accuracy. We observe an approximate degeneracy of energy levels required by Lorentz invariance of the <math altimg='si3.svg'><mi>N</mi><mo stretchy='false'>&#8594;</mo><mo>&#8734;</mo></math> theory.

Poland

Maciej Trzetrzelewski

On Lorentz invariance of the quantum membrane

We propose a novel collider signature for neutral long-lived particles (LLPs): the emerging photon jet in the hadronic calorimeter (HCAL). This signature arises when a neutral LLP decays into photons within the HCAL, producing an electromagnetic shower without associated charged tracks or energy deposits in the electromagnetic calorimeter (ECAL). To demonstrate the viability of this approach, we consider the fermiophobic Higgs boson <math altimg='si1.svg'><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math> in the Type-I two-Higgs-doublet model as a representative scenario. In the ultralight regime ( <math altimg='si2.svg'><msub><mrow><mi>m</mi></mrow><mrow><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>&lt;</mo><mn>1</mn></math> GeV), <math altimg='si1.svg'><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math> decays exclusively into a photon pair via loop-induced processes, resulting in a suppressed width and consequently a long lifetime. Focusing on the golden channel <math altimg='si3.svg'><mi>p</mi><mi>p</mi><mo stretchy='false'>&#8594;</mo><msup><mrow><mi>H</mi></mrow><mrow><mo>&#177;</mo></mrow></msup><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub><mo stretchy='false'>&#8594;</mo><msup><mrow><mi>W</mi></mrow><mrow><mo>&#177;</mo></mrow></msup><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math>, we analyze the exotic final state in which one <math altimg='si1.svg'><msub><mrow><mi>h</mi></mrow><mrow><mi mathvariant='normal'>f</mi></mrow></msub></math> decays in the ECAL and appears as a highly collimated photon jet (reconstructed as a single photon), while the other decays within the HCAL, producing an emerging photon jet. Through a detailed signal-to-background analysis incorporating realistic detector effects via fast simulation, we demonstrate that this signature achieves discovery-level sensitivity at the HL-LHC across a broad region of parameter space consistent with theoretical and experimental constraints. While our study focuses on the fermiophobic Higgs, the emerging photon jet in the HCAL constitutes a broadly applicable and previously unexplored strategy for detecting neutral LLPs decaying into photons, opening a new avenue in LLP searches at colliders.

South Korea

Jinheung Kim

Dongjoo Kim

Soojin Lee

Jeonghyeon Song

Emerging photon jets in the hadronic calorimeter: A novel signature of neutral long-lived particles at the LHC

We investigate the number-of-constituent-quark (NCQ) scaling of elliptic flow for various hadrons in non-central Au+Au collisions at <math altimg='si2.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>3.0</mn><mtext>&#8211;</mtext><mn>7.7</mn><mspace width='0.2em' /><mrow><mi mathvariant='normal'>GeV</mi></mrow></math> using the AMPT model with string melting (SM) and pure hadron cascade (HC) modes. For the SM case, NCQ scaling is absent at <math altimg='si3.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>3.0</mn><mspace width='0.2em' /><mrow><mi mathvariant='normal'>GeV</mi></mrow></math> but is largely restored by <math altimg='si4.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>3.9</mn><mspace width='0.2em' /><mrow><mi mathvariant='normal'>GeV</mi></mrow></math>. Although quark coalescence occurs at <math altimg='si3.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>3.0</mn><mspace width='0.2em' /><mrow><mi mathvariant='normal'>GeV</mi></mrow></math>, the lack of NCQ scaling is attributed to the insufficient development of quark elliptic flow and the limited production of strange quarks and antiquarks. This finding suggests that NCQ scaling could not be considered a definitive signature of quark-gluon plasma (QGP) formation in the RHIC fixed-target energy region. For the HC case, as expected, no NCQ scaling is observed. However, a mass ordering in the elliptic flow emerges at <math altimg='si5.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>4.5</mn><mspace width='0.2em' /><mrow><mi mathvariant='normal'>GeV</mi></mrow></math>, indicating that full thermalization may not be a prerequisite for mass ordering.

Xun Zhu

Gao-Chan Yong

Violation of NCQ scaling in hadron elliptic flow in Au+Au collisions at <math altimg='si1.svg'><msqrt><mrow><msub><mrow><mi>s</mi></mrow><mrow><mi>N</mi><mi>N</mi></mrow></msub></mrow></msqrt><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>3.0</mn><mo linebreak='goodbreak' linebreakstyle='after'>&#8722;</mo><mn>7.7</mn><mspace width='0.2em' /><mrow><mi mathvariant='normal'>GeV</mi></mrow></math>

Inspired by quantum gravity frameworks predicting Planck-scale deviations from Lorentz invariance, we probe Lorentz symmetry violation via modified dispersion relations <math altimg='si1.svg'><msub><mrow><mi>&#969;</mi></mrow><mrow><mo stretchy='false'>|</mo><mtext mathvariant='bold'>k</mtext><mo stretchy='false'>|</mo></mrow></msub></math>. Departing from conventional approaches, we employ an Unruh-DeWitt detector to probe energy-dependent modifications to the dispersion relations. Two key methodological advances are introduced: (i) a generalized formulation for detector acceleration without assuming specific dispersion relations, and (ii) a momentum-resolved detection paradigm enabling spectral decomposition of <math altimg='si1.svg'><msub><mrow><mi>&#969;</mi></mrow><mrow><mo stretchy='false'>|</mo><mtext mathvariant='bold'>k</mtext><mo stretchy='false'>|</mo></mrow></msub></math> through localized momentum-shell integration. Analysis of deviations reveals disruption of the thermal spectrum under significant departures from the Lorentz invariance, while small perturbative regimes manifest as phase-modulated thermal distributions. By restricting detector-field interactions to narrow spectral windows and performing iterative Taylor expansions around reference momenta <math altimg='si12.svg'><mo stretchy='false'>|</mo><msub><mrow><mtext mathvariant='bold'>k</mtext></mrow><mrow><mn>0</mn></mrow></msub><mo stretchy='false'>|</mo></math>, we derive coefficients encoding derivatives of <math altimg='si1.svg'><msub><mrow><mi>&#969;</mi></mrow><mrow><mo stretchy='false'>|</mo><mtext mathvariant='bold'>k</mtext><mo stretchy='false'>|</mo></mrow></msub></math>, reconstructing its global profile via momentum-space tomography. Our approach offers a scalable method to test Lorentz symmetry violation across energy scales, and establishes a foundation for experimental verification of Planck-scale relics through high-precision spectral measurements.

Hao Xu

Momentum-resolved probing of Lorentz-violating dispersion relations via Unruh-DeWitt detector

We evaluate the three-loop five-point pentagon-box-box massless integral family in the dimensional regularization scheme, via canonical differential equation. We use tools from computational algebraic geometry to enable the necessary integral reductions. The boundary values of the differential equation are determined analytically in the Euclidean region. To express the final result, we introduce a new representation of weight six functions in terms of one-fold integrals over the product of weight-three functions with weight-two kernels that are derived from the differential equation. Our work paves the way to the analytic computation of three-loop multileg Feynman integrals.