Tue·Dec 2, 2025Tuesday·December 2, 2025

1. 01*

   A Review on Intense Electromagnetic Fields in Heavy-Ion Collisions: Theoretical Predictions and Experimental Results

   Diyu Shen🇨🇳 · Jinhui Chen🇨🇳 · Xu-Guang Huang🇨🇳 · Yu-Gang Ma🇨🇳 · Aihong Tang🇺🇸 · Gang Wang🇺🇸

   In heavy-ion collisions at relativistic energies, the incident nuclei travel at nearly the speed of light. These collisions deposit kinetic energy into the overlap region and create a high-temperature environment where hadrons ``melt'' into deconfined quarks and gluons. The spectator nucleons, which do not undergo scatterings, generate an ultra-intense electromagnetic field -- on the order of $10^{18}$ Gauss at Relativistic Heavy-Ion Collider, and $10^{19}$ Gauss at the Large Hadron Collider. These powerful electromagnetic fields have a significant impact on the produced particles, not only complicating the study of particle interactions but also inducing novel physical phenomena. To explore the nature of these fields and their interactions with deconfined quarks, we provide a detailed overview, encompassing theoretical estimations of their generation and evolution, as well as experimental efforts to detect them. We also provide physical interpretations of the discovered results and discuss potential directions for future investigations.

   nucl-exhep-phnucl-thResearch(2025)·25 citations
2. 02*

   Probing hard/soft factorization via beam-spin asymmetry in exclusive pion electroproduction from the proton

   Alicia C. Postuma (1)🇨🇦 · Garth M. Huber (1)🇨🇦 · D.J. Gaskell (2)🇺🇸 · N. Heinrich (1)🇨🇦 · T. Horn (3 and 2)🇺🇸 · M. Junaid (1)🇨🇦 · S.J.D. Kay (1 and 4)🇨🇦 · V. Kumar (1)🇨🇦 · P. Markowitz (5)🇺🇸 · J. Roche (6)🇺🇸 · R. Trotta (3)🇺🇸 · A. Usman (1)🇨🇦 and 67 other authors

   Deep exclusive meson production (DEMP) reactions, such as $p(\vec{e},e^{\prime }{\pi }^{+})n$, provide opportunities to study the three-dimensional structure of the nucleon through differential cross section and beam- and target-spin asymmetry measurements. This work aims to probe the onset of the hard/soft factorization regime through the exclusive $p(\vec{e},e^{\prime }{\pi }^{+})n$ reaction, as measured in the KaonLT experiment at Jefferson Lab Hall C. A 10.6 GeV longitudinally polarized electron beam was incident on an unpolarized liquid hydrogen target, and the scattered electron and produced meson were detected in two magnetic focusing spectrometers, enabling precision cross section measurements. The cross section ratio ${\sigma }_{L{T}^{\prime }}/{\sigma }_0$ was extracted from the beam-spin asymmetry $A_{LU}$. The $t$-dependence of ${\sigma }_{L{T}^{\prime }}/{\sigma }_0$ was determined at fixed $Q^2$ and $x_B$ over a range of kinematics from $2<Q^2<6$ GeV${}^2$ above the resonance region ($W>2$ GeV). Furthermore, these data are combined with recent results from CLAS/CLAS12 to determine the $Q^2$-dependence of ${\sigma }_{L{T}^{\prime }}/{\sigma }_0$ at two ($x_B$, $t$) settings. This was fairly flat, with $Q^2$ not having a measurable effect on the value of ${\sigma }_{L{T}^{\prime }}/{\sigma }_0$ in the range explored. Results are compared to predictions from the generalized parton distribution (GPD) formalism, which relies explicitly on hard/soft factorization, and Regge formalism. The Regge models better predict ${\sigma }_{L{T}^{\prime }}/{\sigma }_0$, which suggests that the factorization regime is not yet reached.

   nucl-exhep-exhep-phPLB(2026)·0 citations
3. 03*

   Nuclear modification of heavy flavor decayed dielectrons in relativistic heavy-ion collisions

   Lejing Zhang🇨🇳 · Wen-Jing Xing🇨🇳 · Shanshan Cao🇨🇳 · Guang-You Qin🇨🇳

   Dielectrons from heavy flavor hadron decays not only constitute a crucial background to their thermal spectrum in high-energy nuclear collisions, from which the temperature of the quark-gluon plasma (QGP) is extracted, but also provide a valuable probe of heavy quark interactions with the QGP. Using a linear Boltzmann transport (LBT) model to describe heavy quark evolution inside the QGP and a hybrid fragmentation-coalescence model for their hadronization, we find heavy quark energy loss softens the invariant mass spectrum of their decayed dielectrons and yields a higher value of the extracted QGP temperature, while coalescence hardens the spectrum and yields a lower value. Taking into account full medium effects leads to higher values of the extracted temperature than using vacuum baselines of heavy flavor decayed dielectrons in analyzing the experimental data. In addition, we find the angular correlations between dielectron pairs are sensitive to heavy quark interactions with the QGP: the radial flow of the QGP enhances the near-side correlations, and scatterings between heavy quarks and the QGP broaden the away-side correlations, with elastic and string interactions playing a dominant role.

   ↳ nucl-thhep-phnucl-exSCPMA(2026)·0 citations
4. 04*

   Feasibility Study of Pion and Kaon Structure via the Sullivan Process at EicC

   Zongyang Lu🇨🇳 · Zihan Yu🇨🇳 · Ting Lin🇨🇳 · Yu-Tie Liang🇨🇳 · Rong Wang🇨🇳 · Wan Chang🇨🇳 · Weizhi Xiong🇨🇳

   The Electron--Ion Collider in China (EicC) provides an excellent opportunity to explore the internal structure of pions and kaons via the Sullivan process in deep-inelastic scattering (DIS). In this study, we present detailed projections for the pion and kaon structure functions, $F_2^{\pi }$ and $F_2^K$, at EicC, with a focus on both statistical and systematic uncertainties. Leveraging EicC's high luminosity and broad kinematic coverage, the accessible kinematic region is extended beyond previous measurements. The projected statistical uncertainties for $F_2^{\pi }$ and $F_2^K$ are below 5\% and 8\%, respectively, across most kinematic bins. Systematic uncertainties arising from detector effects have been carefully evaluated. These results significantly enhance the precision of meson structure function measurements and provide important constraints on theoretical models of meson parton distributions. Moreover, this study bridges the gap between fixed-target and collider-era measurements, highlighting the pivotal role of EicC in advancing our understanding of hadronic structure.

   ↳ hep-exnucl-exPRD(2026)·9 citations
5. 05*

   Electron-induced single-pion production to constrain the neutron structure in ${}^{40}$Ar. A proof of concept

   J. García-Marcos🇧🇪 · M. Hooft🇧🇪 · T. Franco-Munoz🇪🇸 · N. Jachowicz🇧🇪 · J.M. Udías🇪🇸 · K. Niewczas🇧🇪 · A. Nikolakopoulos🇺🇸 · R. González-Jiménez🇪🇸

   We study electron-induced single-pion production as a way to constrain the neutron structure of ${}^{40}$Ar, information that is necessary for neutrino experiments using argon detectors. The proposed experimental signal consists in detecting in coincidence the scattered electron, a proton and a ${\pi }^{-}$. We performed simulations compatible with the experimental conditions of the MAMI (University of Mainz) and CLAS (Jefferson Lab) facilities. We have computed cross sections and evaluated the main backgrounds. MAMI is a three-spectrometer system with extremely good energy resolution and small acceptances. We found that, by choosing specific values of the final particle's momenta, the shell structure can be well resolved, with negligible background contributions. CLAS is a large solid angle detector with poorer energy resolution. In both cases, the background can be kept under control by performing cuts in missing energy and missing momentum; however, in CLAS, the shell structure cannot be resolved due to the energy resolution. We conclude that MAMI is particularly appropriate for the proposed experiment, whereas CLAS is better suited for other studies.

   ↳ nucl-thnucl-ex1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.