Results from Lattice QCD

Abstract

Abstract. I present our recent results on the critical end point in the µB-T phase diagram of QCD with two flavours of light dynamical quarks and compare them with similar results from other groups. Implications for a possible energy scan at the RHIC are discussed. I also comment briefly on the new results of great relevance to heavy ion collisions from finite temperature lattice QCD simulations on speed of sound, specific heat and on the fate of J/ψ. IntroductionLattice Quantum Chromo Dynamics (QCD), defined on a space-time lattice, has been our best and most reliable tool to extract non-perturbative physics of the strongly interacting theory for over a decade now. In many cases, such as the hadron spectra or the weak decay constants, the focus of lattice QCD has now shifted to obtaining more precise results. In the fields of strong interest to this conference, namely Relativistic Heavy Ion Collisions and the possible transition to the new Quark-Gluon Plasma (QGP) phase, also there are similar examples : the quark-hadron transition temperature [1], T c , the Wróblewski Parameter [2], λ s and the the equation of state [1]. Already a lot of reliable theoretical information on these physical observables of interest has been predicted by lattice QCD and again the focus is now for better precision. Due to the strong influence of dynamical fermions on thermodynamics and the nature of the phase transition, one still has some way to go before precise prediction for realistic world of two light (u and d) and one heavy (s) flavour become available. Nevertheless, the continuing progress in lattice QCD makes it perhaps a reachable goal. I shall be unable to review all the important recent lattice results in the time available. I have therefore chosen to focus on those with thrust on something new, either conceptually or quantitatively. In particular, I shall cover the new results on the T -µ B phase diagram and the physically interesting question of J/ψ-dissolution/persistence. An interesting theoretical issue these days has been the comparison of predictions of conformally invariant theories with lattice QCD results. I shall show one such comparison along with new results for speed of sound.