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1 Heavy quark potential in full QCD lattice simulations at finite temperature Yuu Maezawa (The Univ. of Tokyo) Tsukuba-Tokyo collaboration Univ. of Tsukuba.

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Presentation on theme: "1 Heavy quark potential in full QCD lattice simulations at finite temperature Yuu Maezawa (The Univ. of Tokyo) Tsukuba-Tokyo collaboration Univ. of Tsukuba."— Presentation transcript:

1 1 Heavy quark potential in full QCD lattice simulations at finite temperature Yuu Maezawa (The Univ. of Tokyo) Tsukuba-Tokyo collaboration Univ. of Tsukuba S. Aoki K. Kanaya Y. Taniguchi E. Ejiri T. Hatsuda N. Ishii N. Ukita The Univ. of Tokyo

2 2 Contents Introduction Formalism of lattice QCD Simulation results Summary  Full-QCD action on lattice  Free energy and potential on lattice  Potential using two-flavor Wilson quarks  Comparison with perturbation theory at T > Tc  Comparison with KS fermion

3 3 Introduction Behavior of string breaking at Behavior of screening effect at  Behavior of heavy quark potential at finite T String breaking at Screening effect at Lattice simulation using full-QCD action (2-flavor)

4 4 Formalism of lattice QCD : link variable  Gluon field  Quark field Kogut-Susskind(KS) fermion action Wilson fermion action Simulation time KS fermion < Wilson fermion × 10 We use the Wilson fermion action. Compare with KS fermion action KS fermion trick

5 5 Free energy and Potential on a lattice McLerran, Svetitsky, PRD 24 (1981) 450 Polyakov loop: Free energy of the quark-antiquark pair Static charged quark Quark- antiquark potential

6 6 Projection operator and Nadkarni, PRD 34 (1986) 3904 Quark-quark potential  Separation to each channel after the Coulomb gauge fixing

7 7 Simulation results Lattice size: Gauge action: RG improved action Fermion action: improved Wilson action (2-flavor) Quark mass: Temperature: Configuration: ≒ 500 confs. Gauge fixing: Coulomb gauge Parameters

8 8 Quark-antiquark potential at T < Tc String breaking Shot range: agree with V (r,T =0) Long range: string breaking

9 9 1 c channel: attractive force 8 c channel: repulsive force Screening effect Quark-antiquark potential at T > Tc

10 10 3 c channel: attractive force 6 c channel: repulsive force Quark-quark potential at T > Tc

11 11 Screening effect at.  Screening effect Yukawa type potential : Casimir factor Fitting the potentials of each channel regarding and as free parameters.

12 12 At high T, potentials of each channel can be written by the same parameters: and. Results of and.

13 13 Relation between and. Effective running coupling determined from reproduces.  Effective running coupling  Screening mass

14 14  Next-to-leading order perturbation Rebhan, PRD 48 (1993) 48  2-loop running coupling parameterization Lattice screening mass is well reproduced by the NLO-type screening mass > 0 on the lattice vs. perturbative screening mass

15 15 Comparison with KS fermion Kaczmarek and Zantow, PRD 71 (2005) 114510  KS fermion with Systematic error due to the difference of action may be as large as 20% in the screening mass. ~ KS fermion Quench

16 16  Heavy quark potential Lattice QCD simulation using 2-flavor Wilson fermion action Summary String breaking at, screening effect at  At, potentials are fitted by At high T, potentials of each channel can be written by the same parameters: and. Effective running coupling determined from reproduces. Lattice screening mass is well reproduced by the NLO-type screening mass. Comparison with KS fermion action Systematic error is as large as 20%


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