Structure of Critical Lines in Quenched Lattice QCD with the Wilson Quark Action

The structure of critical lines of vanishing pion mass for the Wilson quark action is examined in quenched lattice QCD. The numerical evidence is presented that critical lines spread into five branches beyond beta=5.6-5.7 at zero temperature. It is also shown that critical lines disappear in the deconfined phase for the case of finite temperatures.Comment: 11 pages, Latex, 7 Postscript figures, uses epsf.st

Lattice QCD and Hydro/Cascade Model of Heavy Ion Collisions

We report here on a recent lattice study of the QCD transition region at finite temperature and zero chemical potential using domain wall fermions (DWF). We also present a parameterization of the QCD equation of state obtained from lattice QCD that is suitable for use in hydrodynamics studies of heavy ion collisions. Finally, we show preliminary results from a multi-stage hydrodynamics/hadron cascade model of a heavy ion collision, in an attempt to understand how well the experimental data (e.g. particle spectra, elliptic flow, and HBT radii) can constrain the inputs (e.g. initial temperature, freezeout temperature, shear viscosity, equation of state) of the theoretical model.Comment: 10 pages, 12 figures. Proceedings for the 26th Winter Workshop on Nuclear Dynamics, Ocho Rios, Jamaica, Jan 2-9, 201

Lattice QCD with Domain-Wall Fermions

We study the quenched lattice QCD using domain-wall fermions at $\beta=6.0$. Behaviors of both pion mass and the explicit breaking term in the axial Ward-Takahashi identity support the existence of the chiral zero modes. We observe a good agreement between the pion decay constants $f_\pi$ from both the conserved axial current and the local current perturbatively renormalized at 1-loop. Finally the possible existence of the parity broken phase is also examined in this model.Comment: LATTICE99 (Chiral Fermions), 3 page

Decay Rate Asymmetry of Top Squark

We discuss a decay rate asymmetry of the top squark, which is induced by a new source of CP violation intrinsic in the supersymmetric standard model. Although new sources of CP violation in this model are severely constrained from the electric dipole moment of the neutron, an unsuppressed CP-violating phase can still coexist with a top squark whose mass is accessible by near-future colliders. Then the dominant decay mode of the top squark has a width different from its CP conjugate process. The magnitude of this $CP$ asymmetry becomes of order $10^{-3}$.Comment: 11 pages, 1 figur

1++1^{++} Nonet Singlet-Octet Mixing Angle, Strange Quark Mass, and Strange Quark Condensate

Two strategies are taken into account to determine the $f_1(1420)$-$f_1(1285)$ mixing angle $\theta$. (i) First, using the Gell-Mann-Okubo mass formula together with the $K_1(1270)$-$K_1(1400)$ mixing angle $\theta_{K_1}=(-34\pm 13)^\circ$ extracted from the data for ${\cal B}(B\to K_1(1270) \gamma), {\cal B}(B\to K_1(1400) \gamma), {\cal B}(\tau\to K_1(1270) \nu_\tau)$, and ${\cal B}(\tau\to K_1(1420) \nu_\tau)$, gave $\theta = (23^{+17}_{-23})^\circ$. (ii) Second, from the study of the ratio for $f_1(1285) \to \phi\gamma$ and $f_1(1285) \to \rho^0\gamma$ branching fractions, we have two-fold solution $\theta=(19.4^{+4.5}_{-4.6})^\circ$ or $(51.1^{+4.5}_{-4.6})^\circ$. Combining these two analyses, we thus obtain $\theta=(19.4^{+4.5}_{-4.6})^\circ$. We further compute the strange quark mass and strange quark condensate from the analysis of the $f_1(1420)-f_1(1285)$ mass difference QCD sum rule, where the operator-product-expansion series is up to dimension six and to ${\cal O}(\alpha_s^3, m_s^2 \alpha_s^2)$ accuracy. Using the average of the recent lattice results and the $\theta$ value that we have obtained as inputs, we get $/ =0.41 \pm 0.09$.Comment: 10 pages, 1 table, published versio

Finite-temperature chiral transitions in QCD with the Wilson quark action

We investigate the finite-temperature phase structure and the scaling of the chiral condensate in lattice QCD with two degenerate light quarks, using a renormalization group improved gauge action and the Wilson quark action. We obtain a phase diagram which is consistent with that from the parity-flavor breaking scenario. The scaling relation for the chiral condensate assuming the critical exponents and the scaling function of the three dimensional O(4) model is remarkably satisfied for a wide range of parameters. This indicates that the chiral transition in two flavor QCD is of second order in the continuum limit.Comment: LaTeX, 3 pages, 4 EPS figures, Talk presented at LATTICE97 (finite temperature