Fri·Aug 9, 2019Friday·August 9, 2019

1. 01*

   Natural superheavy nuclei in astrophysical data

   Andrey Alexandrov · Victor Alexeev · Alexander Bagulya · Aigerim Dashkina · Mikhail Chernyavsky · Alexei Gippius · Lyudmila Goncharova · Sergei Gorbunov🇷🇺 · Victor Grachev · Galina Kalinina · Nina Konovalova🇷🇺 · Natalia Okateva and 7 other authors

   The paper presents the summary data of the authors' research within the framework of the OLIMPIYA project (the Russian acronym of {\bf OLI}viny iz {\bf M}eteoritov --- {\bf P}oisk tyazholykh {\bf I} sverkhtyazholykh {\bf YA}der / Olivines from meteorites: Search for heavy and superheavy nuclei) and results of track analysis for heavy cosmic ray nuclei (\emph{Z} = 26--129) in olivine crystals from meteorites using an original processing technique. A total of 21,743 tracks of nuclei heavier than iron have been identified in meteoritic matter to date to form the largest database within this charge range. The database includes three tracks of superheavy nuclei with the lifetimes of about a few decades, which can be considered as direct experimental evidence for the existence of natural superheavy nuclei from the "island of stability". Comprehensive comparative analysis of data from two meteorites with different cosmic ray exposure ages, Marjalahti (from 178 to 205 Myr) and Eagle Station (from 35 to 71 Myr), is presented for the first time. The results are discussed within the existing concepts of nuclei formation in astrophysical processes.

   nucl-exastro-ph.HE1 citation
2. 02*

   Recalibration of the binding energy of hypernuclei measured in emulsion experiments and its implications

   Peng Liu🇨🇳 · Jinhui Chen🇨🇳 · Declan Keane🇺🇸 · Zhangbu Xu🇺🇸 · Yu-Gang Ma🇨🇳

   The $\Lambda$ separation energy for $\Lambda$-hypernuclei, denoted $B_{\Lambda }$, measured in 1967, 1968, and 1973 are recalibrated using the current best mass estimates for particles and nuclei. The recalibrated $B_{\Lambda }$ are systematically larger (except in the case of ${}_{\Lambda }^6$He) than the original published values by about 100 keV. The effect of this level of recalibration is very important for light hypernuclei, especially for the hypertriton. The early $B_{\Lambda }$ values measured in 1967, 1968, and 1973 are widely used in theoretical research, and the new results provide better constraints on the conclusions from such studies.

   nucl-exnucl-thCPC(2019)·15 citations
3. 03*

   Entropy production in pp and Pb-Pb collisions at energies available at the CERN Large Hadron Collider

   Patrick Hanus🇩🇪 · Aleksas Mazeliauskas🇨🇭 · Klaus Reygers🇩🇪

   We use experimentally measured identified particle spectra and Hanbury Brown-Twiss radii to determine the entropy per unit rapidity $dS/dy$ produced in $\sqrt{s}=7$ TeV pp and $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV Pb-Pb collisions. We find that $dS/dy=11335\pm 1188$ in 0-10% Pb-Pb, $dS/dy=135.7\pm 17.9$ in high-multiplicity pp, and $dS/dy=37.8\pm 3.7$ in minimum bias pp collisions and compare the corresponding entropy per charged particle $(dS/dy)/(d{N}_{\mathrm{ch}}/dy)$ to predictions of statistical models. Finally, we use the QCD kinetic theory pre-equilibrium and viscous hydrodynamics to model entropy production in the collision and reconstruct the average temperature profile at ${\tau }_0=1$ fm/$c$ for high multiplicity pp and Pb-Pb collisions.

   ↳ hep-phnucl-exnucl-thPRC(2019)·39 citations
4. 04*

   Hydrodynamic attractors, initial state energy and particle production in relativistic nuclear collisions

   Giuliano Giacalone🇫🇷 · Aleksas Mazeliauskas🇨🇭 · Sören Schlichting🇩🇪

   We exploit the concept of hydrodynamic attractors to establish a general relation between the initial state energy and the produced particle multiplicities in high-energy nuclear collisions. When combined with an ab initio model of energy deposition, the entropy production during the pre-equilibrium phase naturally explains the universal centrality dependence of the measured charged particle yields in nucleus-nucleus collisions. We further estimate the energy density of the far-from-equilibrium initial state and discuss how our results can be used to constrain non-equilibrium properties of the quark-gluon plasma.

   ↳ hep-phnucl-exnucl-thPRL(2019)·125 citations
5. 05*

   Kinetic freeze-out in central heavy-ion collisions between 7.7 and 2760 GeV per nucleon pair

   Ivan Melo🇸🇰 · Boris Tomasik🇸🇰

   We fit the single-particle $p_t$ spectra of identified pions, kaons, and (anti)protons from central collisions of gold or lead nuclei at energies between 7.7 and 2760~GeV per nucleon pair. Blast wave model with included resonance production and with an assumption of partial chemical equilibrium is used and the fits are performed with the help of a Gaussian emulator process. A kinetic freeze-out temperature is found about 100~MeV for the lowest collision energies and 80~MeV at the LHC. The average transverse expansion velocity grows with increasing $\sqrt{s_{NN}}$ from 0.45 to 0.65. Due to partial chemical equilibrium, the influence of resonance decays on the shape of the $p_t$ spectra for $\sqrt{s_{NN}}$ above 27~GeV is small.

   ↳ nucl-thhep-phnucl-exJ.Phys.G(2020)·23 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.