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Explore baryon chemical potential, phase diagram, and critical end points in finite density simulation using canonical ensemble approach. Findings shed light on phase boundaries and crossover points in various flavor scenarios. Future plans include implementing improved actions and investigating critical points for three flavors.
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Finite Density Simulation with the Canonical Ensemble Anyi Li, Xiangfei Meng, Andrei Alexandru, Keh-Fei Liu χQCD Collaboration
Outline • Canonical approach • Observables • Baryon chemical potential • Possible phase diagram • Conclusion and future plans Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Canonical Approach Grand canonical partition function Fugacity expansion Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Canonical Approach Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Canonical approach K. F. Liu, QCD and Numerical Analysis Vol. III (Springer,New York, 2005),p. 101. Andrei Alexandru, Manfried Faber, Ivan Horva´th,Keh-Fei Liu, PRD 72, 114513 (2005) Canonical ensembles Discrete Fourier transform Standard HMC Accept/Reject Phase Continues Fourier transform Useful for large k (see X. Meng talk on Tues 3:10pm – 3:30pm) WNEM Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Observables Polyakov loop Baryon chemical potential Phase Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Critical end point crossover Critical end point T T plasma plasma hadrons hadrons coexistent coexistent ρ ρ Phase Diagram Two flavors Four flavors ? Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Phase Boundary Ph. Forcrand,S.Kratochvila, Nucl. Phys. B (Proc. Suppl.) 153 (2006) 62 Maxwell construction : determine phase boundary Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Baryon Chemical Potential Nf = 4 Wilson gauge + fermionaction mπ~ 1 GeV Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Maxwell Construction Nf = 4 Wilson gauge + fermion action Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Phase Boundary (Preliminary) Nf = 4 This work Ph. Forcrand,S.Kratochvila, Nucl. Phys. B (Proc. Suppl.) 153 (2006) 62 Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Baryon Chemical Potential Nf = 2 Wilson gauge + fermion action Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Critical end point T T plasma plasma hadrons hadrons coexistent coexistent ρ ρ Phase Diagram Two flavors Four flavors ? Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Phase Diagram • “S-shape” is observed for Nf = 4 • “S-shape” is not observed down to 0.83Tc for Nf = 2 • Calculation at lower temperature is needed for two flavors Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
crossover Critical end point T plasma hadrons coexistent ρ Three Flavors Nf = 3 Iwasaki gauge + Clover fermionaction Lower quark mass ? Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Three Flavors (Preliminary) Nf = 3 Iwasaki gauge + Clover fermionaction Lower quark mass Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg
Conclusion and Future Plans • Continuous Fourier transform makes larger density simulation feasible • First order is observed for four flavors below Tc • First order is not observed for two flavors down to 0.83Tc • Implement improved action. • Small quark mass • Look for “S-shape” and critical end point for three flavors Finite density simulation with the canonical ensemble Anyi Li - Lattice 2008 Williamsburg