From清华大学物理系haoxw.pptVIP

2005-7-1 LanZhou Media EffectonPentaquark 郝学文 From 清华大学物理系 In corporation with 庄鹏飞，黄旭光 Outline 1. Motivations 2. Method(1) 3. Results(1) 4. Conclusions(1) 5. Method(2) 6. Results(2) 7. Conclusions(2) 8. Outlook Motivations Known: M=1540 MeV, ?25MeV, B=+1, S=+1, Q=+1 Decay channels: Unknown: Spin, Isospin, Parity Questions: How to determine its parity? Can it be formed easily in Heavy Ion Collisions? Can the Temperature and Density Effects help us to solve these questions? Two parts Our work includes two parts: 1, Effect of Chiral Symmetry Restoration on Pentaquark $\Theta^+$ Mass and Width at Finite Temperature and Density; PLB 607 (2005) 78-86 Huang, Hao, Zhuang 2, Photoproduction of pentaquark $Theta^+$and chiral symmetry restoration in hot and dense medium almost finished Method----Lagrangians The effective Lagrangians for the PseudoVector(PV) and PseudoScalar(PS) $N \Theta K$ couplings are (Nam et al, PLB579 (2004) 43 ): This is for the P=+1, remove $i \gamma_5$ to get the L for P=-1. Coupling constants The coupling constants $g_A^*$ and $g$ can be obtained by fixing the mass $M_{\Theta}=1540MeV$ and decay width $\Gamma_{\Theta}=15MeV$ in the vacuum. Propagator Self-Energy The propagator can be written as Pole Equation The complex mass Chiral symmetry Spontaneous chiral symmetry breaking and its restoration in hot and dense medium dominates any hadron system. Chiral dynamics in fully reflected in nucleon mass $M_N$. NJL can describe chiral dynamics well Result of $M_N$ The following figures give the effective nucleon mass as the function of temperature and baryon chemical potential. Result(1) Here we give the temperature dependence of $M_{\Theta^+}$ at $\mu=0, 1GeV$. Result(2) Here we give the chemical potential dependence of $M_{\Theta^+}$ at $T=0,200MeV$. Results(3) Temperature dependence of the medium modification to Theta+ width: Results(4) Chemical potential depende