HEP Lattice·hep-lat
5 papers—4 primary·1 cross-listed·reconstructed*
Changhoan Kim🇺🇸 · Norman H. Christ🇺🇸
In order to directly compute physical two-pion K-decay amplitudes using lattice methods we must prepare a two-pion state with non-zero relative momentum. Building upon a proposal of Lellouch and Lüscher, we describe a finite-volume method to realize such a state as the lowest energy state of two pions.
Vicente Azcoiti🇪🇸 · Giuseppe Di Carlo🇮🇹 · Angelo Galante🇮🇹 · Victor Laliena🇪🇸
A new approach to perform numerical simulations of systems with a theta-vacuum term is proposed, tested, and applied to CP3 The main new ingredient of this approach is the method used to compute the probability distribution function of the topological charge at theta=0. We comment also on the possibility of applying this approach to QCD at finite baryon density.
We present results for the renormalised light and strange quark masses calculated using Domain Wall Fermions in quenched QCD. New results using the DBW2 gauge action at inverse lattice spacings of approximately 2 GeV and 1.3 GeV will be presented and compared against existing results at 2 GeV using the Wilson gauge action. This comparison allows a study of the uncertainties due to both finite lattice spacing and residual chiral symmetry breaking effects.
Shigemi Ohta (Institute of Particle and Nuclear Studies, KEK, Japan)🇯🇵
The domain wall fermion (DWF) method, with its almost perfectly preserved chiral symmetry on the lattice, makes the calculation of the nucleon axial charge particularly easy. By maintaining chiral symmetry and using the Ward-Takahashi (WT) identity, one has Z_A = Z_V and the bare lattice calculation yields the physical value without explicit renormalization. The DBW2 improved gauge action provides further enhancement of the symmetry and hence a more accurate WT identity at coarse lattice spacing. Taking advantage of these methods, we confirmed a significant volume dependence of the nucleon axial charge on (1.2 fm)^3 and (2.4 fm)^3 lattice volumes.
The temperature evolution of the chiral condensates in a gas made of pions, kaons and etas is studied within the framework of SU(2) and SU(3) Chiral Perturbation Theory. We describe the temperature dependence of the quark condensates by using the meson meson scattering phase shifts in a second order virial expansion. We find that the SU(3) formalism yields an extrapolated melting temperature for the non-strange condensates which is lower by about 20-30 MeV than within SU(2). In addition our results show that the strange condensate melting is slower than that of the non-strange, due to the different strange and non-strange quark masses.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.