Thermodynamics of two-flavor lattice QCD with an improved Wilson quark action at non-zero temperature and density. Yu Maezawa (Univ. of Tokyo) In collaboration with S. Aoki, K. Kanaya, N. Ishii, N Ukita (Univ. of Tsukuba) T. Hatsuda (Univ. of Tokyo) S. Ejiri (BNL). WHOT-QCD Collaboration.
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Yu Maezawa (Univ. of Tokyo)
In collaboration with
S. Aoki, K. Kanaya, N. Ishii, N Ukita (Univ. of Tsukuba)
T. Hatsuda (Univ. of Tokyo)
S. Ejiri (BNL)
1. Set the lattice spacing and quark mass precisely
2. Understand uncertainties from lattice formulations
Accurate calculation of physical quantities at T = 0
Comparison between different fermion formulations is necessary.
e.g. Wilson quark action and Staggered quark action
To remove theoretical uncertainties in heavy-ion experiments,
First principle calculations by Lattice QCD at finite (T, m): important
Two key issues for precision lattice study
Poster session by Y. Maezawa
1, A well-improved lattice action available:
Basic properties at T = 0 well-investigated
Iwasaki (RG) improved gauge action+ Clover improved Wilson action
Systematic studies have been done by CP-PACS Collaboration (1996~).
Large stock of data at T = 0
2, Most of studies at T0 have been done using Staggered-type quark actions.
Studies by a Wilson-type quark action are necessary.
Previous studies at T0, mq=0 with this action (1999-2001) : phase structure, Tc, O(4) scaling, equation of state, etc.
Three topics covered in this talk
Two-flavor full QCD simulation
1, Critical temperature
Quench limit Chiral limit
Tc in Sommer scale unit
Ambiguity of Sommer scale (r0): 10% difference
Studies at T = 0 are also very important for the determination of Tc.
Both results seem to approach the same line in the continuum limit (large Nt).
2, Fluctuations at finite m
Quark number susceptibility
Fluctuations at finite m
At critical point:
Confirmation by a Wilson-type quark action
Critical point at m0
Event by event fluctuations in heavy ion collisions
In numerical simulations
Quark number and isospin susceptibilities
Hatta and Stephanov, PRL 91 (2003) 102003
Bielefeld-Swansea Collab. (2003) using improved staggered quark action,
Enhancement in the fluctuation of quark number at mq > 0 near Tc
by Taylor expansion method
Dashed Line: 9cq, prediction by hadron resonance gas model
RG + Clover Wilson
Large enhancement in the fluctuation of baryon number (not in isospin) around Tpc as mq increases: Critical point?
Quark number (cq) and Isospin (cI) susceptibilities
p4-improved staggered quark , Bielefeld-Swqnsea Collab., Phys. Rev. D71, 054508 (2005)
3, Heavy quark free energy and Debye screening mass in QGP medium
Today's poster session by Y. Maezawa
Debye screening mass from Polyakov loop correlation
Chiral extrapolation with Nt=4, 6
Simulation with smaller mass and lattice spacing are in progress
Fluctuation and quark number susceptibility at finite mq
Large enhancement in the fluctuation of baryon number around Tpc as m increase
Indication of critical point at m > 0?
Heavy quark free energies and Debye mass in QGP
(Poster session of Y. Maezawa)