Nuclear Theory·nucl-th

Tuesday·December 16, 2025

15 papers—7 primary·8 cross-listed

08
Jet momentum reconstruction in the QGP background with machine learning
Ran Li🇨🇳 · Yi-Lun Du🇨🇳 · Shanshan Cao🇨🇳
We apply a Dense Neural Network (DNN) approach to reconstruct jet momentum within a quark-gluon plasma (QGP) background, using simulated data from PYTHIA and Linear Boltzmann Transport (LBT) Models for comparative analysis. We find that medium response particles from the LBT simulation, scattered out of the QGP background but belonging to medium-modified jets, lead to oversubtraction of the background if the DNN model is trained on vacuum jets from PYTHIA simulation. By training the DNN model on quenched jets generated using LBT or the combination of jet samples from PYTHIA and LBT, we significantly reduce this prediction bias and achieve more accurate background subtraction compared to conventional Area-based and Constituent Subtraction methods widely adopted in experimental measurements. We further study the performance of these machine learning models on evaluating the nuclear modification factor of jets, and find that while the unfolding procedure is necessary for correcting residuals in reconstructed jet momenta, models trained on samples incorporating quenched jets still achieve superior accuracy than those trained on vacuum jets even after unfolding.
↳ hep-phnucl-exnucl-thPLB(2025)·3 citations
09
Dynamical study of hidden-strange pentaquarks as analogs of the hidden-charm states
Xuejie Liu🇨🇳 · Yue Tan🇨🇳 · Yuheng Wu🇨🇳 · Dianyong Chen🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳
Motivated by the recent BESIII experiment~\cite{BESIII:2024muk} searching for hidden-strange exotic hadrons, we perform a systematic theoretical study of the hidden-strange pentaquark system within the framework of the quark delocalization color screening model (QDCSM) and the resonating group method (RGM). Our results demonstrate that the channel coupling effect plays a decisive role in the formation of bound and resonance states. It not only significantly enhances the short-range attraction but also induces essential attractive contributions from pion exchange. We predict three bound states with masses of $1759$ MeV, $2000$ MeV, and $2407$ MeV. Furthermore, we report the existence of a hidden-strange pentaquark resonance state, $Ξ K^{*}$ , with quantum numbers $I (J^{P}) = 0 (1/ 2^{-})$ . This resonance is identified in the $S$ -wave scattering phase shifts of the $Λ η_{s}$ and $Λ ϕ$ open channels, with a predicted mass in the range of $2204 - 2208$ MeV. By accounting for both the scattering width from channel coupling and the intrinsic decay width of the constituent $K^{*}$ , the total decay width is estimated to be $55 - 63$ MeV. These theoretical predictions provide important guidance for future experimental searches for such exotic states at facilities like BESIII.
↳ hep-phnucl-thEPJC(2026)·1 citation
10
From DGLAP to Sudakov: Precision Predictions for Energy-Energy Correlators
Max Jaarsma🇳🇱 · Yibei Li🇩🇪 · Ian Moult🇺🇸 · Wouter J. Waalewijn🇳🇱 · Hua Xing Zhu🇨🇳
Correlations in the distribution of energy produced in collider experiments provide a snapshot of the microscopic dynamics of QCD, and its evolution from asymptotically free quarks and gluons, to confined hadrons. There has recently been considerable progress in the interpretation and precision calculation of these correlations, using a specific class of observables called energy correlators (EECs). These observables are most cleanly studied in $e^{+} e^{-}$ collisions, where they can be measured over their full angular range. Of particular interest are kinematic limits of the correlator, both collinear, and back-to-back, where the correlator exhibits scaling behaviors governed by specific operators in QCD. Resolving these scalings requires measurements with exceptional angular resolution, which can be achieved by performing measurements on tracks (charged particles). In this paper we perform the first calculation of the track-based EEC over its entire kinematic range, achieving a record precision of of NNLL (collinear) + NNLO (fixed order) + NNNNLL (back-to-back) for the track-based EEC, and additionally incorporate the leading non-perturbative corrections and their resummation, including the Collins-Soper kernel computed using lattice QCD. We describe the breadth of physics probed by this observable, and highlight the impact of different components of our factorization theorem on the final distribution. Combined with recent measurements of the track-based EEC with archival LEP data, our calculation initiates the precision study of track-based observables at LEP, which will lead to new insights into the dynamics of QCD, and the precision extraction of its underlying parameters.
↳ hep-phhep-exhep-thnucl-ex+123 citations
11
Directional dead-cone effect in QCD matter
João Barata🇨🇭 · Matvey V. Kuzmin🇪🇸 · Xoán Mayo López🇪🇸 · Andrey V. Sadofyev🇪🇸 · Carlos A. Salgado🇪🇸
We consider the propagation of heavy quarks through a dense, hydrodynamically flowing QCD medium, representative of the quark-gluon plasma formed in ultrarelativistic heavy-ion collisions. Working in the high-energy limit, we identify two novel mass-dependent effects arising from the heavy quark coupling to the local medium flow. The first is the emergence of a tensorial jet transport coefficient, $q^_{ij}$ , which encodes the directional structure of transverse-momentum broadening. The second, named the directional dead-cone effect, corresponds to an anisotropic suppression of medium-induced radiation aligned with the hydrodynamic flow. We discuss how these effects manifest in jet observables and identify distinctive signature of heavy quark dynamics in an evolving medium.
↳ hep-phhep-exnucl-th5 citations
12
Renormalization Group Evolution for In-medium Energy Correlators
Weiyao Ke🇨🇳 · Bianka Mecaj🇺🇸 · Ivan Vitev🇺🇸
We present a first-principles analysis of the renormalization group (RG) evolution of the two-point energy-energy correlator (EEC) in light-quark and gluon jets propagating through nuclear matter. Our work focuses on the analytic structure of the RG equations in the thin-medium regime, highlighting how collinear emissions in the presence of a dense QCD medium reshape the EEC observables. We work in the opacity expansion of the SCET $_{G}$ formalism, where the propagating quarks and gluons interact with the medium via Glauber gluon exchanges. We compute the corresponding one-loop jet functions using the medium-induced splitting kernels at first order in opacity and perform resummation at leading logarithmic (LL) order. In particular, we identify an experimentally accessible regime of jet energies and EEC angles where one can directly investigate the medium-induced scale evolution and extract the corresponding opacity-one correction to the anomalous dimensions. Furthermore, we demonstrate analytically, using the method of regions, the Coulomb-logarithmic enhancement regulated by plasma screening for EEC. We compare our theoretical predictions with experimental data in $p$ -Pb collisions and make projections for O-O collisions to test whether energy correlators could serve as sensitive probe of the quark-gluon plasma (QGP) dynamics in small collision systems, offering a robust and model-independent avenue for constraining jet evolution in QCD matter.
↳ hep-phnucl-thJHEP(2026)·12 citations
13
Relativistic Dispersion Spectra across Lorentz boosted frames: Spurious modes and the enigma of causality
Sayantani Bhattacharyya🇬🇧 · Sukanya Mitra🇮🇳 · Shuvayu Roy🇮🇳 · Rajeev Singh🇷🇴
The analysis of excitation spectra in gradient-expanded relativistic fluid theories frequently leads to pathologies under Lorentz boosts. However, extracting the dispersion modes in a Lorentz boosted inertial frame can be nontrivial. Motivated by this problem, we develop a general framework for deriving the linearized dispersion spectra in Lorentz boosted frames using only information from the local rest-frame dispersion structure, particularly its mode-expansion coefficients. We observe that, under a Lorentz transformation from the local rest frame, additional boosted solutions may appear that conflict with the causality of the theory; we refer to these as "spurious modes." The key developments presented here are: (i) a convenient method for obtaining dispersion spectra across inertial frames, bypassing the traditional procedure of solving the boosted polynomial, and (ii) the establishment of a direct connection between mode conservation and the causality of a theory, supported by a detailed proof.
↳ hep-thgr-qchep-phnucl-thJHEP(2026)·4 citations
14
Sign Reversal of Boer-Mulders Functions from Semi-inclusive Deep-Inelastic Scattering to the Drell-Yan Process
Jen-Chieh Peng🇺🇸 · Ming-Xiong Liu🇺🇸 · Guanghua Xu🇺🇸
A striking prediction of QCD on the properties of the novel Transverse Momentum Dependent (TMD) distribution functions is that the time-reversal odd Sivers and Boer-Mulders functions extracted from semi-inclusive deep-inelastic scattering (SIDIS) will undergo a sign reversal in the Drell-Yan (DY) process. This prediction has been tested by experiments that have focused on the Sivers functions so far. We examine the current status on the theoretical prediction and experimental extraction of the signs of the Boer-Mulders functions from SIDIS and DY. We show that the existing SIDIS and DY data are consistent with the predicted sign reversal of the Boer-Mulders functions for proton's valence quark distribution. Prospects for future experiments at EIC capable of testing the sign reversal of the pion Boer-Mulders functions are also discussed.
↳ hep-phnucl-exnucl-thPLB(2026)·1 citation
15
Probing the pion gluon distribution at small- $x$ in photon-induced interactions at LHC
Victor P. Goncalves🇧🇷 · Juciene T. de Souza🇧🇷 · Diego Spiering🇧🇷
In this paper we propose the analysis of the heavy quark photoproduction associated with a leading neutron in hadronic collisions at the LHC as an alternative to probe the pion gluon distribution in a kinematical range not covered by previous experiments. We perform an exploratory study of the charm and bottom photoproduction associated with a leading neutron in proton-proton ( $pp$ ) and proton-lead ( $pP b$ ) collisions, and present calculations for the rapidity distributions and cross-sections. Our predictions indicate that experimental studies of these processes are feasible, and that a future measurement of this final state will be useful to constrain the pion gluon distribution at small values of the Bjorken $x$ variable and to improve our understanding of the pion structure.
↳ hep-phhep-exnucl-exnucl-thPRD(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE