Wed·Jul 29, 2020Wednesday·July 29, 2020

1. 01*

   Flow and interferometry results from Au+Au collisions at $\sqrt{{\text{s}}_{NN}}$ = 4.5 GeV

   STAR Collaboration: J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · D. M. Anderson · A. Aparin · E. C. Aschenauer · M. U. Ashraf and 355 other authors

   The Beam Energy Scan (BES) program at the Relativistic Heavy Ion Collider (RHIC) was extended to energies below $\sqrt{{\text{s}}_{NN}}$ = 7.7 GeV in 2015 by successful implementation of the fixed-target mode of operation in the STAR (Solenoidal Track At RHIC) experiment. In the fixed-target mode, ions circulate in one ring of the collider and interact with a stationary target at the entrance of the STAR Time Projection Chamber. The first results for Au+Au collisions at $\sqrt{{\text{s}}_{NN}}$ = 4.5 GeV are presented, including directed and elliptic flow of identified hadrons, and radii from pion femtoscopy. The proton flow and pion femtoscopy results agree quantitatively with earlier measurements by Alternating Gradient Synchrotron experiments at similar energies. This validates running the STAR experiment in the fixed-target configuration. Pion directed and elliptic flow are presented for the first time at this beam energy. Pion and proton elliptic flow show behavior which hints at constituent quark scaling, but large error bars preclude reliable conclusions. The ongoing second phase of BES (BES-II) will provide fixed-target data sets with 100 times more events at each of several energies down to $\sqrt{{\text{s}}_{NN}}$ = 3.0 GeV.

   nucl-exPRC(2021)·115 citations
2. 02*

   Charged particle production in $pp$ collisions at $\sqrt{s}$=8, 7 and 2.76 TeV at the LHC -- a case study

   R. Aggarwal🇮🇳 · M. Kaur🇮🇳

   We analyse the charged$\text{-}$particle multiplicity distributions measured by the ALICE experiment, over a wide pseudorapidity range, for $pp$ collisions at $\sqrt{s}$=8,\,7\,and\, 2.76~TeV at the LHC.~The analysis offers an understanding of particle production in high energy collisions in the purview of a new distribution, the shifted Gompertz distribution.~Data are compared with the distribution and moments of the distributions are calculated.~A modified version of the distribution is also proposed and used to improve the description of the data consisting of two different event classes; the inelastic and the non$\text{-}$single$\text{-}$diffractive and their subsets in different windows of pseudorapidity, $\eta$.~The distribution used to analyse the data has a wide range of applicability to processes in different fields and complements the analysis done by the ALICE collaboration in terms of various LHC event generators and IP-Glasma calculations.

   ↳ hep-exnucl-exIJMPE(2021)·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.