One of the most challenging issues in QCD is the investigation of spontaneous chiral-symmetry breaking, which is characterized by the non-vanishing chiral condensate when the bare fermion mass is zero. In standard methods of the lattice gauge theory, one has to perform expensive simulations at multiple bare quark masses, and employ some modeled functions to extrapolate the data to the chiral limit. This paper applies the probability distribution function method to computing the chiral condensate in lattice QCD with massless dynamical quarks, without any ambiguous mass extrapolation. The results for staggered quarks indicate that this might be a promising and efficient method for investigating the spontaneous chiral-symmetry breaking in lattice QCD, which deserves further investigation.
LUO XiangQian Department of Physics,School of Physics and Engineering,Sun Yat-Sen University,Guangzhou 510275,China
We investigate the bound states of the Yukawa potential V(r)=-λexp(-αr)/r, using different algorithms: solving the Schrodinger equation numerically and our Monte Carlo Hamiltonian approach. There is a critical α = αC, above which no bound state exists. We study the relation between αC and A for various angular momentum quantum number l. and find in atomic units, αC(l) = λ[A1 exp(-l/B1) + A2exp(-l/B2)], with A1 = 1.020(18), B1 = 0.443(14), A2 = 0.170(17), and B2 = 2.490(180).
LI Yongyao1,LUO Xiangqian1 & Helmut Krōger2 1. Department of Physics,Sun Yat-sen University,Guangzhou 510275,China
