Mon·Jul 10, 2017Monday·July 10, 2017

1. 01*

   Beam Energy Dependence of Jet-Quenching Effects in Au+Au Collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV

   STAR Collaboration: L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · N. N. Ajitanand · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin and 334 other authors

   We report measurements of the nuclear modification factor, $R_{\mathrm{CP}}$, for charged hadrons as well as identified ${\pi }^{+(-)}$, $K^{+(-)}$, and $p(\overline{p})$ for Au+Au collision energies of $\sqrt{s_{{}_{\mathrm{NN}}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, and 62.4 GeV. We observe a clear high-$p_{\mathrm{T}}$ net suppression in central collisions at 62.4 GeV for charged hadrons which evolves smoothly to a large net enhancement at lower energies. This trend is driven by the evolution of the pion spectra, but is also very similar for the kaon spectra. While the magnitude of the proton $R_{\mathrm{CP}}$ at high $p_{\mathrm{T}}$ does depend on collision energy, neither the proton nor the anti-proton $R_{\mathrm{CP}}$ at high $p_{\mathrm{T}}$ exhibit net suppression at any energy. A study of how the binary collision scaled high-$p_{\mathrm{T}}$ yield evolves with centrality reveals a non-monotonic shape that is consistent with the idea that jet-quenching is increasing faster than the combined phenomena that lead to enhancement.

   nucl-exhep-exPRL(2018)·84 citations
2. 02*

   The Way Forward - Closing Remarks at Quark Matter 2017

   W.A. Zajc🇺🇸

   This contribution is a written version of my closing talk presented at the Quark Matter 2017 conference. Neither the talk nor this contribution to the conference proceedings is intended as a comprehensive summary. Rather, a brief discussion is presented of emerging themes and challenges in the field of relativistic heavy ion physics.

   nucl-exnucl-thNPA(2017)·1 citation
3. 03*

   Measurement of the $\pi K$ atom lifetime and the $\pi K$ scattering length

   DIRAC Collaboration: B. Adeva🇪🇸 · L. Afanasyev🇷🇺 · Y. Allkofer🇨🇭 · C. Amsler🇨🇭 · A. Anania🇮🇹 · S. Aogaki🇷🇴 · A. Benelli🇨🇿 · V. Brekhovskikh🇷🇺 · T. Cechak🇨🇿 · M. Chiba🇯🇵 · P. Chliapnikov🇷🇺 · D. Drijard🇨🇭 and 52 other authors

   After having announced the statistically significant observation (5.6~$\sigma$) of the new exotic $\pi K$ atom, the DIRAC experiment at the CERN proton synchrotron presents the measurement of the corresponding atom lifetime, based on the full $\pi K$ data sample: $\tau =(5.5_{-2.8}^{+5.0})\cdot 10^{-15}s$. By means of a precise relation ($<1\%$) between atom lifetime and scattering length, the following value for the S-wave isospin-odd $\pi K$ scattering length $a_0^{-}=\frac{1}{3}(a_{1/2}-a_{3/2})$ has been derived: $\left|a_0^{-}\right|=(0.072_{-0.020}^{+0.031})M_{\pi }^{-1}$.

   ↳ hep-exnucl-exPRD(2017)·18 citations
4. 04*

   New theories of relativistic hydrodynamics in the LHC era

   Wojciech Florkowski🇵🇱 · Michal P. Heller🇩🇪 · Michal Spalinski🇵🇱

   The success of relativistic hydrodynamics as an essential part of the phenomenological description of heavy-ion collisions at RHIC and the LHC has motivated a significant body of theoretical work concerning its fundamental aspects. Our review presents these developments from the perspective of the underlying microscopic physics, using the language of quantum field theory, relativistic kinetic theory, and holography. We discuss the gradient expansion, the phenomenon of hydrodynamization, as well as several models of hydrodynamic evolution equations, highlighting the interplay between collective long-lived and transient modes in relativistic matter. Our aim to provide a unified presentation of this vast subject -- which is naturally expressed in diverse mathematical languages -- has also led us to include several new results on the large-order behaviour of the hydrodynamic gradient~expansion.

   ↳ hep-phgr-qchep-thnucl-ex+1Rept.Prog.Phys.(2018)·410 citations
5. 05*

   Optimization of the final settings for the Space-borne Hard X-ray Compton Polarimeter POLAR

   Hualin Xiao🇨🇭 · Wojtek Hajdas🇨🇭 · Radaslow Marcinkowski (for the POLAR collaboration)🇵🇱

   POLAR is a compact wide field space-borne detector dedicated for precise measurements of the linear polarization of hard X-rays emitted by transient sources in the energy range from 50 keV to 500 keV. It consists of 1600 plastic scintillator bars grouped in 25 detector modules that are used as gamma-ray detection material. Its energy range sensitivity is optimized for detection of the prompt emission photons from the gamma-ray bursts. Measurements of the GRB polarization provide unique information on emission mechanisms as well as on composition and structure of the GRB jets. The POLAR instrument was developed by international collaboration of Switzerland, China and Poland. It was launched in space on-board the China Space Laboratory TG-2 on September 15th, 2016. Based on the ground calibration data, several high voltage and threshold settings were calculated and verified in order to obtain various energy ranges and optimized signal to background conditions for different measurement purposes. In this paper we present optimization procedure details and current test results.

   ↳ physics.ins-detastro-ph.IMnucl-exPoS(2018)·2 citations
6. 06*

   Are minimal conditions for collectivity met in e+e- collisions?

   J.L. Nagle🇺🇸 · R. Belmont🇺🇸 · K. Hill🇺🇸 · J. Orjuela Koop🇺🇸 · D.V. Perepelitsa🇺🇸 · P. Yin🇺🇸 · Z-W. Lin🇺🇸 · D. McGlinchey🇺🇸

   Signatures of collective behavior have been measured in highly relativistic p+p collisions, as well as in p+A, d+A, and 3He+A collisions. Numerous particle correlation measurements in these systems have been successfully described by calculations based on viscous hydrodynamic and transport models. These observations raise the question of the minimum necessary conditions for a system to exhibit collectivity. Recently, numerous scientists have raised the question of whether the quarks and gluons generated in e+e- collisions may satisfy these minimum conditions. In this paper we explore possible signatures of collectivity, or lack thereof, in e+e- collisions utilizing A Multi-Phase Transport (AMPT) framework which comprises melted color strings, parton scattering, hadronization, and hadron re-scattering.

   ↳ nucl-thnucl-exPRC(2018)·36 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.