889 research outputs found

    Exact relations for thermodynamics of heavy quarks

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    We derive finite-temperature sum rules for excesses in internal energy and in (volume-integrated) pressure arising due to presence of heavy quarks in SU(N) gluon plasma. In the limit of zero temperature our formulae reduce to the Michael-Rothe sum rules. The excesses in energy and pressure of the gluon plasma are related to expectation values of certain gluon condensates, and, simultaneously, to the heavy quark potential. The sum rules lead to a known relation between the internal energy and the potential, and to a new expression for the excess in the pressure. The pressure appears in the free energy as a generalized force associated with variations of the spatial size of the heavy-quark system. We find that the excess in gluonic pressure around a heavy quarkonium is always negative. Finally, we derive an exact equation of state that provides a relationship between the gluonic energy and pressure of heavy quarks.Comment: 7 page

    Bottomonium spectrum at order v^6 from domain-wall lattice QCD: precise results for hyperfine splittings

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    The bottomonium spectrum is computed in dynamical 2+1 flavor lattice QCD, using NRQCD for the b quarks. The main calculations in this work are based on gauge field ensembles generated by the RBC and UKQCD collaborations with the Iwasaki action for the gluons and a domain-wall action for the sea quarks. Lattice spacing values of approximately 0.08 fm and 0.11 fm are used, and simultaneous chiral extrapolations to the physical pion mass are performed. As a test for gluon discretization errors, the calculations are repeated on two ensembles generated by the MILC collaboration with the Luscher-Weisz gauge action. Gluon discretization errors are also studied in a lattice potential model using perturbation theory for four different gauge actions. The nonperturbative lattice QCD results for the radial and orbital bottomonium energy splittings obtained from the RBC/UKQCD ensembles are found to be in excellent agreement with experiment. To get accurate results for spin splittings, the spin-dependent order-v^6 terms are included in the NRQCD action, and suitable ratios are calculated such that most of the unknown radiative corrections cancel. The cancellation of radiative corrections is verified explicitly by repeating the calculations with different values of the couplings in the NRQCD action. Using the lattice ratios of the S-wave hyperfine and the 1P tensor splitting, and the experimental result for the 1P tensor splitting, the 1S hyperfine splitting is found to be 60.3+-5.5(stat)+-5.0(syst)+-2.1(exp) MeV, and the 2S hyperfine splitting is predicted to be 23.5+-4.1(stat)+-2.1(syst)+-0.8(exp) MeV.Comment: 36 pages, 14 figures. v2: added Appendix D containing detailed analysis of gluon discretization errors using a lattice potential model and comparison to results from MILC ensembles. Estimates of systematic errors in hyperfine splittings now include gluon discretization errors and b-bbar annihilation contribution. Accepted for publication in PR

    On Fluctuations of Conserved Charges : Lattice Results Versus Hadron Resonance Gas

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    We compare recent lattice results on fluctuations and correlations of strangeness, baryon number and electric charge obtained with p4 improved staggered action with the prediction of hadron resonance gas model. We show that hadron resonance gas can describe these fluctuations reasonably well if the hadron properties are as calculated on the lattice.Comment: 4 pages, LaTeX, uses jpconf.cls, to appear in the proceedings of 26th Winter Workshop on Nuclear Dynamic

    Static meson correlators in 2+1 flavor QCD at non-zero temperature

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    We study correlation functions of various static meson operators of size r at non-zero temperature in 2+1 flavor QCD, including Coulomb gauge fixed operators and Wilson loops with smeared spatial parts. The numerical calculations are performed on 24^3x6 lattices using highly improved staggered quark action. We discuss possible implications of our findings on the temperature dependence of the static energy of QQbar pair.Comment: 10 pages LaTeX, 7 figures, uses svjour.cl
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