Fri·Aug 30, 2024Friday·August 30, 2024

1. 01*

   Flavor Dependence of Charged Pion Fragmentation Functions

   H. Bhatt🇺🇸 · P. Bosted🇺🇸 · S. Jia🇺🇸 · W. Armstrong🇺🇸 · D. Dutta🇺🇸 · R. Ent🇺🇸 · D. Gaskell🇺🇸 · E. Kinney🇺🇸 · H. Mkrtchyan · S. Ali🇺🇸 · R. Ambrose🇨🇦 · D. Androic🇭🇷 and 58 other authors

   We have measured the flavor dependence of multiplicities for pi^+ and pi^- production in semi-inclusive deep-inelastic scattering (SIDIS) on proton and deuteron targets to explore a possible charge symmetry violation in fragmentation functions. The experiment used an electron beam with energies of 10.2 and 10.6 GeV at Jefferson Lab and the Hall-C spectrometers. The electron kinematics spanned the range 0.3<x<0.6, 2<Q^2<5.5 GeV^2, and 4<W^2<11 GeV^2. The pion fractional momentum range was 0.3< z <0.7, and the transverse momentum range was 0<p_T<0.25 GeV/c. Assuming factorization at low p_T and allowing for isospin breaking, we find that the results can be described by two "favored" and two "un-favored" effective low $p_T$ fragmentation functions that are flavor-dependent. However, they converge to a common flavor-independent value at the lowest x or highest W of this experiment.

   nucl-exhep-phnucl-thPLB(2025)·7 citations
2. 02*

   Event-activity-dependent beauty-baryon enhancement in simulations with color junctions

   Lea Virág Földvári🇭🇺 · Zoltán Varga🇭🇺 · Róbert Vértesi🇭🇺

   Recent results from ALICE and CMS show a low-transverse-momentum enhancement of charm baryon-to-meson production ratios over model predictions based on e${}^{+}$e${}^{-}$ collisions. Several mechanisms are proposed to understand this phenomenon. New measurements by the LHCb and ALICE experiments show a similar enhancement in the beauty sector. We explore this enhancement in terms of event activity using the color-reconnection beyond leading order approximation model. We propose sensitive probes relying on the event shape that will allow for the differentiation between the proposed beauty-production scenarios using freshly collected LHC Run-3 data, and we also compare these to predictions for charm. Our results will contribute to a deeper theoretical understanding of the heavy-flavor baryon enhancement and its relation to baryon enhancement in general.

   ↳ hep-phnucl-exInt.J.Mod.Phys.A(2025)·0 citations
3. 03*

   Distinguishing the sources of dielectron anisotropic flow at low beam energies

   Renan Hirayama🇩🇪 · Hannah Elfner🇩🇪

   We present calculations of dielectron anisotropic flow in heavy-ion collisions at HADES beam energies from a hadronic transport approach. The ongoing experimental analysis employs the traditional reaction plane method to evaluate the flow coefficients $v_n$ and claims to see isotropic radiation from the thermal quark-gluon plasma. We show in this work, that in the region above the pion mass, the dilepton flow measurement might suffer from cancellation effects that mask the complicated underlying dynamics. Contributions from different baryonic and mesonic resonances show collective behaviour with different signs and lead to an overall vanishing elliptic flow. To differentiate the different contributions, we propose to employ the scalar product method, which exploits the previously measured hadronic flow to create different reference planes. As a proof of concept, we calculate the $v_2$ of dielectrons for Ag+Ag collisions at $\sqrt{s_{NN}}=2.55$ $\mathrm{GeV}$ with both methods and investigate the contribution of each source, concluding that the scalar product method provides the proton and pion tagged flow coefficients as two distinct measurements, disentangling the various dilepton sources.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2024)·7 citations
4. 04*

   The X17 boson and the d(p,e+ e-)3He and d(n,e+ e-)3H processes: a theoretical analysis

   M. Viviani🇮🇹 · E. Filandri🇮🇹 · L. Girlanda🇮🇹 · C. Gustavino🇮🇹 · A. Kievsky🇮🇹 · L.E. Marcucci🇮🇹

   The present work deals with the e+ e- pair production in the d(p,e+e-)3He and d(n,e+ e-)3H processes, in order to evidentiate possible effects due to the exchange of a hypothetical low-mass boson, the so-called X17. These processes are studied for energies of the incident beams in the range 18-30 MeV, in order to have a sufficient energy to produce such a boson, whose mass is estimated to be around 17 MeV. We first analyze them as a purely electromagnetic processes, in the context of a state-of-the-art approach to nuclear strong-interaction dynamics and nuclear electromagnetic currents, derived from chiral effective field theory chiEFT. Next, we examine how the exchange of a hypothetical low-mass boson would impact the cross sections for such processes. We consider several possibilities, that this boson is either a scalar, pseudoscalar, vector, or axial particle. The main aim of the study is to exploit the specular structure of the 3He and 3H nuclei to investigate the isospin dependency of the X17-nucleon interaction, as the alleged "proto-phobicity".

   ↳ nucl-thnucl-exPRC(2025)·2 citations

* 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.