Fri·Oct 27, 2017Friday·October 27, 2017

1. 01*

   Charmonium production in p-Pb collisions with ALICE at the LHC

   Biswarup Paul (for the ALICE Collaboration)🇮🇹

   The suppression of quarkonium production with respect to pp collisions is one of the most distinctive signatures of the formation of quark-gluon plasma (QGP), a hot nuclear medium created in ultrarelativistic heavy-ion collisions. However, the suppression of heavy quarkonium production with respect to pp collisions can also take place in p-A collisions, where QGP is not expected to be created and only cold nuclear matter (CNM) effects, such as nuclear absorption, parton shadowing and parton energy loss in initial and final states occur. The study of p-A collisions is therefore important to disentangle the effects of QGP from the CNM ones, and to provide essential input to understand the nucleus-nucleus collisions. The ALICE Collaboration at the LHC has studied inclusive J/$\psi$ production, in the dimuon decay channel, at forward rapidity (2.03 $<$ $y_{\mathrm{cms}}$ $<$ 3.53) and backward rapidity ($-$4.46 $<$ $y_{\mathrm{cms}}$ $<$ $-$2.96) in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV with the Muon Spectrometer. In this contribution, we present the measurement of the nuclear modification factor of inclusive J/$\psi$ as a function of the centrality and we show the comparison of this result with the one at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.

   nucl-exPoS(2017)·2 citations
2. 02*

   Evidence for the role of proton shell closure in quasi-fission reactions from X-ray fluorescence of mass-identified fragments

   M. Morjean (GANIL)🇫🇷 · D.J. Hinde🇦🇺 · C. Simenel🇦🇺 · D.Y. Jeung🇦🇺 · M. Airiau (IPNO, IRFU)🇫🇷 · K.J. Cook🇦🇺 · M. Dasgupta🇦🇺 · A. Drouart (IRFU)🇫🇷 · D. Jacquet (IPNO)🇫🇷 · S. Kalkal🇦🇺 · C.S. Palshetkar🇦🇺 · E. Prasad🇦🇺 and 5 other authors

   The atomic numbers and the masses of fragments formed in quasi-fission reactions have been simultaneously measured at scission in 48 Ti + 238 U reactions at a laboratory energy of 286 MeV. The atomic numbers were determined from measured characteristic fluorescence X-rays whereas the masses were obtained from the emission angles and times of flight of the two emerging fragments. For the first time, thanks to this full identification of the quasi-fission fragments on a broad angular range, the important role of the proton shell closure at Z = 82 is evidenced by the associated maximum production yield, a maximum predicted by time dependent Hartree-Fock calculations. This new experimental approach gives now access to precise studies of the time dependence of the N/Z (neutron over proton ratios of the fragments) evolution in quasi-fission reactions.

   nucl-exnucl-thPRL(2017)·37 citations
3. 03*

   Measurements of mass-dependent azimuthal anisotropy in central $p$$+$Au, $d$$+$Au, and ${}^3$He$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV

   A. Adare · C. Aidala · N.N. Ajitanand · Y. Akiba · M. Alfred · V. Andrieux · N. Apadula · H. Asano · B. Azmoun · V. Babintsev · A. Bagoly · M. Bai and 342 other authors

   We present measurements of the transverse-momentum dependence of elliptic flow $v_2$ for identified pions and (anti)protons at midrapidity ($|\eta |<0.35$), in 0%--5% central $p$$+$Au and ${}^3$He$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV. When taken together with previously published measurements in $d$$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV, the results cover a broad range of small-collision-system multiplicities and intrinsic initial geometries. We observe a clear mass-dependent splitting of $v_2(p_T)$ in $d$$+$Au and ${}^3$He$+$Au collisions, just as in large nucleus-nucleus ($A$$+$$A$) collisions, and a smaller splitting in $p$$+$Au collisions. Both hydrodynamic and transport model calculations successfully describe the data at low $p_T$ ($<1.5$ GeV/$c$), but fail to describe various features at higher $p_T$. In all systems, the $v_2$ values follow an approximate quark-number scaling as a function of the hadron transverse kinetic energy per constituent quark($K{E}_T/n_q$), which was also seen previously in $A$$+$$A$ collisions.

   nucl-exhep-exPRC(2018)·44 citations
4. 04*

   Comparing standard distribution and its Tsallis form of transverse momenta in high energy collisions

   Rui-Fang Si🇨🇳 · Hui-Ling Li🇨🇳 · Fu-Hu Liu🇨🇳

   In this paper, the experimental (simulated) transverse momentum spectra of negatively charged pions produced at mid-rapidity in central nucleus-nucleus collisions at the Heavy Ion Synchrotron (SIS), Relativistic Heavy Ion Collider (RHIC), and Large Hadron Collider (LHC) energies obtained by different collaborations are selected by us to investigate, where a few simulated data are taken from the results of FOPI Collaboration who uses the IQMD transport code based on Quantum Molecular Dynamics. A two-component standard distribution and the Tsallis form of standard distribution are used to fit these data in the framework of a multisource thermal model. The excitation functions of main parameters in the two distributions are analyzed. In particular, the effective temperatures extracted from the two-component standard distribution and the Tsallis form of standard distribution are obtained, and the relation between the two types of effective temperatures is studied.

   ↳ nucl-thhep-exhep-phnucl-exAdv.High Energy Phys.(2018)·13 citations
5. 05*

   Study of Lambda polarization at RHIC BES and LHC energies

   Iurii Karpenko🇫🇷 · Francesco Becattini🇮🇹

   In hydrodynamic approach to relativistic heavy ion collisions, hadrons with nonzero spin, produced out of the hydrodynamic medium, can acquire polarization via spin-vorticity thermodynamic coupling mechanism. The hydrodynamical quantity steering the polarization is the thermal vorticity, that is minus the antisymmetric part of the gradient of four-temperature field. Based on this mechanism there have been several calculations in hydrodynamic and non-hydrodynamic models for non-central heavy ion collisions in the RHIC Beam Energy Scan energy range, showing that the amount of polarization of produced $\Lambda$ hyperons ranges from few percents to few permille, and decreases with collision energy. We report on an extension of our existing calculation of global $\Lambda$ polarization in UrQMD+vHLLE model to full RHIC and LHC energies, and discuss the component of polarization along the beam direction, which is the dominant one at high energies.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2018)·5 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.