Wed·May 16, 2018Wednesday·May 16, 2018

1. 01*

   Measurement of jet fragmentation in Pb+Pb and $pp$ collisions at $\sqrt{s_{NN}}=5.02$ TeV with the ATLAS detector

   ATLAS Collaboration

   This paper presents a measurement of jet fragmentation functions in 0.49 nb${}^{-1}$ of Pb+Pb collisions and 25 pb${}^{-1}$ of $pp$ collisions at $\sqrt{s_{NN}}=5.02$ TeV collected in 2015 with the ATLAS detector at the LHC. These measurements provide insight into the jet quenching process in the quark-gluon plasma created in the aftermath of ultra-relativistic collisions between two nuclei. The modifications to the jet fragmentation functions are quantified by dividing the measurements in Pb+Pb collisions by baseline measurements in $pp$ collisions. This ratio is studied as a function of the transverse momentum of the jet, the jet rapidity, and the centrality of the collision. In both collision systems, the jet fragmentation functions are measured for jets with transverse momentum between 126 GeV and 398 GeV and with an absolute value of jet rapidity less than 2.1. An enhancement of particles carrying a small fraction of the jet momentum is observed, which increases with centrality and with increasing jet transverse momentum. Yields of particles carrying a very large fraction of the jet momentum are also observed to be enhanced. Between these two enhancements of the fragmentation functions a suppression of particles carrying an intermediate fraction of the jet momentum is observed in Pb+Pb collisions. A small dependence of the modifications on jet rapidity is observed.

   nucl-exhep-exPRC(2018)·136 citations
2. 02*

   Measurement of the nuclear modification factor for inclusive jets in Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector

   ATLAS Collaboration

   Measurements of the yield and nuclear modification factor, $R_{\mathrm{AA}}$, for inclusive jet production are performed using 0.49 nb${}^{-1}$ of Pb+Pb data at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV and 25 pb${}^{-1}$ of $pp$ data at $\sqrt{s}=5.02$ TeV with the ATLAS detector at the LHC. Jets are reconstructed with the anti-$k_t$ algorithm with radius parameter $R=0.4$ and are measured over the transverse momentum range of 40-1000 GeV in six rapidity intervals covering $|y|<2.8$. The magnitude of $R_{\mathrm{AA}}$ increases with increasing jet transverse momentum, reaching a value of approximately 0.6 at 1 TeV in the most central collisions. The magnitude of $R_{\mathrm{AA}}$ also increases towards peripheral collisions. The value of $R_{\mathrm{AA}}$ is independent of rapidity at low jet transverse momenta, but it is observed to decrease with increasing rapidity at high transverse momenta.

   nucl-exhep-exPLB(2019)·296 citations
3. 03*

   Multiplicity and Underlying Event in ALICE: as measurements and as tools to probe QCD

   Valentina Zaccolo (on behalf of the ALICE Collaboration)🇮🇹

   With the high collision energies at the LHC, the contributions to particle production from hard-QCD processes increase, but it remains dominated by soft-QCD processes. Such processes challenge the theoretical models, since they are described by non-perturbative phenomenology. A selection of the most recent ALICE measurements of charged-particle multiplicities and the Underlying Event will be presented, focusing on model comparisons. A summary of the current understanding of soft-QCD processes will be discussed, evaluating possible ways to further constrain theory.

   nucl-ex1 citation
4. 04*

   Deuteron analysing powers in deuteron-proton elastic scattering at 1.2 and 2.27 GeV

   D.Mchedlishvili🇬🇪 · Z.Bagdasarian🇩🇪 · S.Barsov🇷🇺 · S.Dymov🇩🇪 · R.Engels🇩🇪 · R.Gebel🇩🇪 · K.Grigoryev🇩🇪 · J.Haidenbauer🇩🇪 · M.Hartmann🇩🇪 · A.Kacharava🇩🇪 · I.Keshelashvili🇩🇪 · A.Khoukaz🇩🇪 and 22 other authors

   The vector and tensor analysing powers in deuteron-proton elastic scattering have been measured in the forward hemisphere at deuteron kinetic energies of 1.2 GeV and 2.27 GeV using the ANKE spectrometer at the COSY storage ring. The results are compared with other experimental data and with predictions made within the framework of Glauber multiple scattering theory.

   nucl-exnucl-thNPA(2018)·8 citations
5. 05*

   Measurement of the ${}^{20}$F half-life

   M. Hughes🇺🇸 · E.A. George · O. Naviliat-Cuncic🇫🇷 · P.A. Voytas · S. Chandavar🇺🇸 · A. Gade🇺🇸 · X. Huyan🇺🇸 · S.N. Liddick🇺🇸 · K. Minamisono · S.V. Paulauskas🇺🇸 · D. Weisshaar🇺🇸

   The half-life of the ${}^{20}$F ground state has been measured using a radioactive beam implanted in a plastic scintillator and recording $\beta \gamma$ coincidences together with four CsI(Na) detectors. The result, $T_{1/2}=11.0011(69{)}_{\mathrm{stat}}(30{)}_{\mathrm{sys}}$~s, is at variance by 17 combined standard deviations with the two most precise results. The present value revives the poor consistency of results for this half-life and calls for a new measurement, with a technique having different sources of systematic effects, to clarify the discrepancy.

   nucl-exPRC(2018)·7 citations
6. 06*

   Chemical potentials of light flavor quarks from yield ratios of negative to positive particles in Au+Au collisions at RHIC

   Ya-Qin Gao🇨🇳 · Hai-Ling Lao🇨🇳 · Fu-Hu Liu🇨🇳

   The transverse momentum spectra of ${\pi }^{-}$, ${\pi }^{+}$, $K^{-}$, $K^{+}$, $\bar{p}$, and $p$ produced in Au+Au collisions at center-of-mass energy $\sqrt{s_{NN}}=7.7$, 11.5, 19.6, 27, 39, 62.4, 130, and $200$ GeV are analyzed in the framework of a multisource thermal model. The experimental data measured at midrapidity by the STAR Collaboration are fitted by the (two-component) standard distribution. The effective temperature of emission source increases obviously with the increase of the particle mass and the collision energy. At different collision energies, the chemical potentials of up, down, and strange quarks are obtained from the antiparticle to particle yield ratios in given transverse momentum ranges available in experiments. With the increase of logarithmic collision energy, the chemical potentials of light flavor quarks decrease exponentially.

   ↳ nucl-thhep-exhep-phnucl-exAdv.High Energy Phys.(2018)·4 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.