Wed·Jul 4, 2018Wednesday·July 4, 2018

1. 01*

   Measurement of dielectron production in central Pb-Pb collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}$ = 2.76 TeV

   ALICE Collaboration

   The first measurement of dielectron (${\mathrm{e}}^{+}{\mathrm{e}}^{-}$) production in central (0$-$10$\%$) Pb-Pb collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}$ = 2.76 TeV at the LHC is presented. The dielectron invariant-mass spectrum is compared to the expected contributions from hadron decays in the invariant-mass range $0<m_{\mathrm{ee}}<3.5\mathrm{GeV}/{\text{c}}^2$. The ratio of data and the cocktail of hadronic contributions without vacuum ${\rho }^0$ is measured in the invariant-mass range $0.15<m_{\mathrm{ee}}<0.7\mathrm{GeV}/{\text{c}}^2$, where an excess of dielectrons is observed in other experiments, and its value is $1.40\pm 0.28(stat.)\pm 0.08(syst.)\pm 0.27(\mathrm{cocktail})$. The dielectron spectrum measured in the invariant mass range $0<m_{\mathrm{ee}}<1\mathrm{GeV}/{\text{c}}^2$ is consistent with the predictions from two theoretical model calculations that include thermal dielectron production from both partonic and hadronic phases with in-medium broadened ${\rho }^0$ meson. The fraction of direct virtual photons over inclusive virtual photons is extracted for dielectron pairs with invariant mass $0.1<m_{\mathrm{ee}}<0.3\mathrm{GeV}/{\text{c}}^2$, and in the transverse-momentum intervals $1<p_{\mathrm{T},\mathrm{ee}}<2\mathrm{GeV}/\text{c}$ and $2<p_{\mathrm{T},\mathrm{ee}}<4\mathrm{GeV}/\text{c}$. The measured fraction of virtual direct photons is consistent with the measurement of real direct photons by ALICE and with the expectations from previous dielectron measurements at RHIC within the experimental uncertainties.

   nucl-exhep-exPRC(2019)·58 citations
2. 02*

   Observation of Gaussian pseudorapidity distributions for produced particles in proton-nucleus collisions at Tevatron energies

   U. U. Abdurakhmanov🇺🇿 · K. G. Gulamov🇺🇿 · V. V. Lugovoi🇺🇿 · V. Sh Navotny🇺🇿

   The statistical event-by-event analysis of inelastic interactions of protons in emulsion at 800 GeV reveals the existence of group of events with Gaussian pseudorapidity distributions for produced particles, as suggested by hydrodynamic-tube model. Events belong to very central collisions of protons with heavy emulsion nuclei with probability of realization of less than 1% and with multiplicity of shower particles exceeding (2-3 times) the average multiplicity in proton-nucleus collisions in emulsion. The Bjorken's energy density for these events reaches 2.0 GeV per fm^3. The data are interpreted as a result of the QCD phase transition in proton-tube collisions at Tevatron energies.

   nucl-ex0 citations
3. 03*

   PISTA: Posterior Ion STAcking

   Johannes Bellm🇸🇪 · Christian Bierlich🇸🇪

   We present a program allowing for the construction of a heavy ion Monte Carlo event using a general purpose proton--proton event generator of the users' choice to deliver sub--collisions. In this heavy ion event, one or more jets can be added, again using a jet calculation of the users' choice, allowing for more realistic simulation studies of jets in a heavy ion background.

   ↳ hep-phhep-exnucl-exnucl-th7 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.