Wed·Aug 3, 2011Wednesday·August 3, 2011

1. 01*

   PHENIX Measurements of Higher-order Flow Harmonics in Au+Au collisions at Root_s = 200 GeV

   Roy Lacey (for the PHENIX Collaboration) · (Stony Brook University)

   Flow coefficients $v_n$ for $n$ = 2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV, are presented. They indicate the expected growth of viscous damping for sound propagation in the quark gluon plasma (QGP) produced in these collisions. Hydrodynamical model comparisons which include the effects of initial state geometry fluctuations, highlight the role of higher harmonics ($v_{n,n>2}$) as a constraint for disentangling the effects of viscosity and initial conditions, and suggest a small specific viscosity for the QGP. This viscosity is compatible with that obtained via a newly proposed technique \cite{Lacey:2011ug} which employs the relative magnitudes of $v_n$ to estimate the viscosity, and the "viscous horizon" or length-scale which characterizes the highest harmonic that survives viscous damping.

   nucl-exJ.Phys.G(2011)·28 citations
2. 02*

   Beam-Target Double Spin Asymmetry A_LT in Charged Pion Production from Deep Inelastic Scattering on a Transversely Polarized He-3 Target at 1.4<Q^2<2.7 GeV^2

   J. Huang🇺🇸 · K. Allada🇺🇸 · C. Dutta🇺🇸 · J. Katich🇺🇸 · X. Qian🇺🇸 · Y. Wang🇺🇸 · Y. Zhang🇨🇳 · K. Aniol🇺🇸 · J. R. M. Annand🇬🇧 · T. Averett🇺🇸 · F. Benmokhtar🇺🇸 · W. Bertozzi🇺🇸 and 103 other authors

   We report the first measurement of the double-spin asymmetry $A_{LT}$ for charged pion electroproduction in semi\nobreakdash-inclusive deep\nobreakdash-inelastic electron scattering on a transversely polarized ${}^3$He target. The kinematics focused on the valence quark region, $0.16<x<0.35$ with $1.4<Q^2<2.7{\text{GeV}}^2$. The corresponding neutron $A_{LT}$ asymmetries were extracted from the measured ${}^3$He asymmetries and proton over ${}^3$He cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function $g_{1T}^q$ and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for ${\pi }^{-}$ production on ${}^3$He and the neutron, while our ${\pi }^{+}$ asymmetries are consistent with zero.

   nucl-exhep-exPRL(2012)·87 citations
3. 03*

   Model independent determination of the axial mass parameter in quasielastic neutrino-nucleon scattering

   Bhubanjyoti Bhattacharya🇺🇸 · Richard J. Hill🇺🇸 · Gil Paz🇺🇸

   Quasielastic neutrino-nucleon scattering is a basic signal process for neutrino oscillation studies. At accelerator energies, the corresponding cross section is subject to significant uncertainty due to the poorly constrained axial-vector form factor of the nucleon. A model-independent description of the axial-vector form factor is presented. Data from the MiniBooNE experiment for quasielastic neutrino scattering on carbon are analyzed under the assumption of a definite nuclear model. The value of the axial mass parameter, m_A=0.85^{+0.22}_{-0.07} +/- 0.09 GeV, is found to differ significantly from extractions based on traditional form factor models. Implications for future neutrino scattering and pion electroproduction measurements are discussed.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2011)·157 citations
4. 04*

   Interaction model for the gap equation

   Si-xue Qin🇨🇳 · Lei Chang🇺🇸 · Yu-xin Liu🇨🇳 · Craig D. Roberts🇺🇸 · David J. Wilson🇺🇸

   We explain a form for the rainbow-ladder kernel whose momentum-dependence is consonant with modern DSE- and lattice-QCD results, and assess its capability as a tool in hadron physics. In every respect tested, this form produces results for observables that are at least equal to the best otherwise obtained in a comparable approach. Moreover, it enables the natural extraction of a monotonic running-coupling and -gluon-mass.

   ↳ nucl-thhep-lathep-phnucl-exPRC(2011)·254 citations
5. 05*

   Quark Recombination and Heavy Quark Diffusion in Hot Nuclear Matter

   Rainer J. Fries🇺🇸 · Min He🇺🇸 · Ralf Rapp🇺🇸

   We discuss resonance recombination for quarks and show that it is compatible with quark and hadron distributions in local thermal equilibrium. We then calculate realistic heavy quark phase space distributions in heavy ion collisions using Langevin simulations with non-perturbative T-matrix interactions in hydrodynamic backgrounds. We hadronize the heavy quarks on the critical hypersurface given by hydrodynamics after constructing a criterion for the relative recombination and fragmentation contributions. We discuss the influence of recombination and flow on the resulting heavy meson and single electron R_AA and elliptic flow. We will also comment on the effect of diffusion of open heavy flavor mesons in the hadronic phase.

   ↳ nucl-thnucl-exJ.Phys.G(2011)·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.