Mon·Jun 24, 2024Monday·June 24, 2024

1. 01*

   Electric Conductivity of QCD Matter and Dilepton Spectra in Heavy-Ion Collisions

   Ralf Rapp🇺🇸

   The electric conductivity, ${\sigma }_{\mathrm{el}}$, is a fundamental transport coefficient of QCD matter that can be related to the zero-energy limit of the electromagnetic (EM) spectral function at vanishing 3-momentum in the medium. The EM spectral function is also the central quantity to describe the thermal emission rates and pertinent spectra of photon and dilepton radiation in heavy-ion collisions. Employing a model for dilepton rates that combines hadronic many-body theory with nonperturbative QGP emission constrained by lattice-QCD which describes existing dilepton measurements in heavy-ion collisions, we investigate the sensitivity of low-mass dilepton spectra in Pb-Pb collisions at the LHC to ${\sigma }_{\mathrm{el}}$. In particular, we disentangle the contributions from QGP and hadronic emission, and identify signatures that can help to extract ${\sigma }_{\mathrm{el}}$ from high-precision experimental data expected to be attainable with future detector systems at the LHC.

   ↳ hep-phnucl-exnucl-thPRC(2024)·12 citations
2. 02*

   First Measurement of Deeply Virtual Compton Scattering on the Neutron with Detection of the Active Neutron

   CLAS Collaboration: A. Hobart🇫🇷 · S. Niccolai🇫🇷 · M. Čuić🇭🇷 · K. Kumerički🇭🇷 · P. Achenbach🇺🇸 · J.S. Alvarado🇫🇷 · W.R. Armstrong🇺🇸 · H. Atac🇺🇸 · H. Avakian🇺🇸 · L. Baashen🇺🇸 · N.A. Baltzell🇺🇸 · L. Barion🇮🇹 and 136 other authors

   Measuring Deeply Virtual Compton Scattering on the neutron is one of the necessary steps to understand the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). Neutron targets play a complementary role to transversely polarized proton targets in the determination of the GPD $E$. This poorly known and poorly constrained GPD is essential to obtain the contribution of the quarks' angular momentum to the spin of the nucleon. DVCS on the neutron was measured for the first time selecting the exclusive final state by detecting the neutron, using the Jefferson Lab longitudinally polarized electron beam, with energies up to 10.6 GeV, and the CLAS12 detector. The extracted beam-spin asymmetries, combined with DVCS observables measured on the proton, allow a clean quark-flavor separation of the imaginary parts of the GPDs $H$ and $E$.

   ↳ hep-exnucl-exPRL(2024)·18 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.