Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session H6: Relativistic Heavy Ions: p+ p and p+ A |
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Sponsoring Units: DNP Chair: Abhisek Sen, University of Tennessee Room: 200 |
Sunday, April 6, 2014 8:30AM - 8:42AM |
H6.00001: Measurement of heavy flavor decay electrons in proton-proton collisions at $\sqrt{s}$ = 7 TeV Irakli Martashvili Charm and beauty quarks serve as probes of this hot and dense QCD matter produced, since they are formed in early stages of these collisions. A measurement of heavy flavor production in pp collisions serves as an essential baseline for a comparison to p-Pb and Pb-Pb collisions, as well as providing important tests of perturbative QCD calculations at the highest available energies. The ALICE experiment has several subdetectors capable of measuring heavy flavor via their decay products. The Electromagnetic Calorimeter (EMCal), Time Projection Chamber (TPC), Time of Flight detector and Transition Radiation Detector are used to identify electrons across a wide range of momenta and measure their yields and kinematic distributions. The EMCal is capable of measuring the energy deposited by electrons with high momenta, while the TPC provides electron identification up to 7 GeV/c and measurement of charged particle momenta with high precision. Moreover, the EMCal trigger enhances ALICE capabilities for selecting electrons at high transverse momenta. Details of the heavy flavor decay electron analysis at mid rapidity ($|\eta|<0.7$) in pp collisions at $\sqrt{s}$ = 7 TeV including electron transverse momentum spectra and event selection criteria will be presented. [Preview Abstract] |
Sunday, April 6, 2014 8:42AM - 8:54AM |
H6.00002: Strange baryon vs meson ratio in near-side and away-side jets in p$+$p collisions at ALICE using azimuthal correlations Sandun Jayarathna Pahula Hewage Two-particle azimuthal correlations are an ideal probe to study high pT parton fragmentation without full jet reconstruction [1-2]. Enhancements of the azimuthal correlations are seen at $\Delta \varphi =$ 0 and $\Delta \varphi = \pi $, indicating the near-side and away-side jets, respectively [3]. We will present the ongoing work on correlations between charged leading particles and the associated strange baryons and mesons in p$+$p at $\surd $sNN $=$ 7 TeV. The aim of this work is to study the strange baryon vs meson ratio in near- and away-side jets, as well as underlying events, using azimuthal correlations. This study is done in different pT intervals in the 1-6 GeV/c range for the associated particles. \\[4pt] [1]. J. Adams et al., Phys. Rev. Lett. 91, 072304 (2003)\\[0pt] [2]. F.Q. Wang, (STAR Collaboration), J. Phys. G30, S1299 (2004)\\[0pt] [3]. Adler C et al. (STAR Collaboration), Phys. Rev. Lett. 90, 082302 (2003) [Preview Abstract] |
Sunday, April 6, 2014 8:54AM - 9:06AM |
H6.00003: ABSTRACT WITHDRAWN |
Sunday, April 6, 2014 9:06AM - 9:18AM |
H6.00004: ABSTRACT WITHDRAWN |
Sunday, April 6, 2014 9:18AM - 9:30AM |
H6.00005: Higher harmonics from intrinsic multi-particle production Kevin Dusling We explore the detailed structure of the {\em ridge} in the Color-Glass-Condensate (CGC) effective field theory of QCD and demonstrate a novel mechanism that produces a non-vanishing $v_3$ without final-state re-scattering. A $v_3$ in agreement with the LHC p+Pb data is generated by the interference of diagrams attributed to the jet (away-side) and ridge (near-side) substructure of the azimuthal correlation. [Preview Abstract] |
Sunday, April 6, 2014 9:30AM - 9:42AM |
H6.00006: Production of electrons from heavy flavor decays in p-Pb collisions at $\surd$s $\sqrt{s_{NN}}$ = 5.02 TeV measured with ALICE Rebecca Scott Ultrarelativistic nucleus-nucleus collisions at the Large Hadron Collider are used to study nuclear matter under high temperature and energy density by creating a Quark Gluon Plasma (QGP). Complementary studies of p-Pb collisions were meant to isolate cold nuclear matter effects and mechanisms unrelated to the presence of a QGP. However there are some recent hints that there may also be collective effects in p-Pb collisions making the separation of cold and hot nuclear matter effects more challenging. In Pb-Pb collisions, heavy quarks, charm and beauty, are created early in the collision and traverse the entire evolution thus making them a good probe of the medium. In p-Pb collisions, initial and final state effects related to the presence of cold nuclear matter can affect the heavy-flavor yield. Electrons from semileptonic decays of charm and beauty hadrons provide one way of measuring heavy flavor production in p-Pb collisions. The status of the current analysis of electrons from heavy flavor decays in p-Pb collisions, with particular emphasis on the electron identification, will be presented. [Preview Abstract] |
Sunday, April 6, 2014 9:42AM - 9:54AM |
H6.00007: Spatial meson correlators at non-zero and dissolution of charmonium states Peter Petreczky, Alexei Bazavov, Frithjof Karsch, Swagato Mukherjee, Yu Maezawa We study charmonium correlation functions in spatial directions in lattice QCD at non-zero temperature. We perform calculations in 2+1 flavor QCD with phyical values of the quark masses using highly improved staggered quark (HISQ) formulation. Athough the relation between the spatial charmonium correlation function and the spectral properties of charmonium is a bit complicated, spatial correlation functions can be studied at large separations and therefore are very sensitive to the in-medium modification and/or melting of charmonium states. We find that the correlation functions corresponding to 1S state show small modification around the transition temperature, but the modifications are are very large at temperatures T$>$300 MeV, consistent with the dissolution of the bound state. The correlation functions corresponding to 1P charmonium on the other hand, show significant in-medium modifications at the transition temperature. This confirms the expected sequential melting pattern of different charmonium states. Finally we compare the temperature dependence of charmonium correla. [Preview Abstract] |
Sunday, April 6, 2014 9:54AM - 10:06AM |
H6.00008: Untriggered di-hadron correlations using 2.76 TeV Pb-Pb collisions in ALICE Danthasinghe Piyarathna We present measurements of untriggered di-hadron correlations as a function of mean $p_{\rm{T}}$ in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV at ALICE. The momentum evolution of untriggered data has been studied by increasing the lower $p_{\rm{T}}$ acceptance of both charged particles and within momentum windows. A smooth evolution of the correlation structures is observed. We further quantify the evolution of the contributing components by fitting a model function. The model function emphasizes possible initial state fluctuation contributions via the use of higher harmonics, $v_{n}$ (n = 2, 3, 4, 5). A remainder is modeled via an asymmetric 2D Gaussian to extract parameters of the long range $\Delta\eta$ correlations, referred to as the ``soft ridge.'' In order to model nonflow contributions (via a 2D Gaussian) Fourier harmonics [1] are shown with and without such a 2D Gaussian. Extracted harmonics parameters are compared with published ALICE flow results [2] and IP Glasma model predictions [3].\\[4pt] [1] A.M Adare et al.(ALICE Collaboration), Phys. Lett. B 708 (2012)\\[0pt] [2] K. Aamodt et al.(ALICE Collaboration), Phys. Rev. Lett. 107, 032301(2011)\\[0pt] [3] Prithwish Tribedy (private comm.) [Preview Abstract] |
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