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JLQCD collaboration

Publications and source records attributed to JLQCD collaboration.

23 records · Page 2Linked to original sources
arXiv2003

An Exact Algorithm for Any-flavor Lattice QCD with Kogut-Susskind Fermion

We propose an exact simulation algorithm for lattice QCD with dynamical Kogut-Susskind fermion in which the N_f-flavor fermion operator is defined as the N_f/4-th root of the Kogut-Susskind (KS) fermion operator. The algorithm is an extension of the Polynomial Hybrid Monte Carlo (PHMC) algorithm to KS fermions. The fractional power of the KS fermion operator is approximated with a Hermitian Chebyshev polynomial, with which we can construct an algorithm for any number of flavors. The error which arises from the approximation is corrected by the Kennedy-Kuti noisy Metropolis test. Numerical simulations are performed for the two-flavor case for several lattice parameters in order to confirm the validity and the practical feasibility of the algorithm. In particular tests on a 16^4 lattice with a quark mass corresponding to m_{PS}/m_V ~ 0.68 are successfully accomplished. We conclude that our algorithm provides an attractive exact method for dynamical QCD simulations with KS fermions.

hep-lat↗
arXiv2001

Differential decay rate of $B \to πl ν$ semileptonic decay with lattice NRQCD

We present a lattice QCD calculation of $B\to πl ν$ semileptonic decay form factors in the small pion recoil momentum region. The calculation is performed on a quenched $16^3 \times 48$ lattice at $β=5.9$ with the NRQCD action including the full 1/M terms. The form factors $f_1(v\cdot k_π)$ and $f_2(v\cdot k_π)$ defined in the heavy quark effective theory for which the heavy quark scaling is manifest are adpoted, and we find that the 1/M correction to the scaling is small for the $B$ meson. The dependence of form factors on the light quark mass and on the recoil energy is found to be mild, and we use a global fit of the form factors at various quark masses and recoil energies to obtain model independent results for the physical differential decay rate. We find that the $B^*$ pole contribution dominates the form factor $f^+(q^2)$ for small pion recoil energy, and obtain the differential decay rate integrated over the kinematic region $q^2 >$ 18 GeV$^2$ to be $|V_{ub}|^2 \times (1.18 \pm 0.37 \pm 0.08 \pm 0.31)$ psec$^{-1}$, where the first error is statistical, the second is that from perturbative calculation, and the third is the systematic error from finite lattice spacing and the chiral extrapolation. We also discuss the systematic errors in the soft pion limit for $f^0(q^2_{max})$ in the present simulation.

hep-lat↗
arXiv1997

B meson decay constant from quenched Lattice QCD

A lattice QCD calculation of the B meson decay constant is presented. In order to investigate the scaling violation associated with the heavy quark, parallel simulations are carried out employing both Wilson and the O(a)-improved clover actions for the heavy quark. The discretization errors due to the large $b$ quark mass are estimated in a systematic way with the aid of the non-relativistic interpretation approach of El-Khadra, Kronfeld and Mackenzie. As our best value from the quenched simulations at $β$=5.9, 6.1 and 6.3 we obtain $f_B$=163$\pm$16 MeV and $f_{B_s}$=175$\pm$18 MeV in the continuum limit where the error includes both statistical and systematic uncertainties.

hep-lat↗
arXiv1997

B meson decay constant with the Wilson and Clover heavy quark actions

We present results of our quenched study of the B meson decay constant obtained with a parallel set of simulations with the Wilson and Clover actions at β=5.9, 6.1 and 6.3. Systematic errors associated with the large b-quark mass are analyzed within the Fermilab non-relativistic formalism. As our best estimate in the continuum limit we obtain $f_B=163 \pm 16 MeV$ and $f_{B_s}=175 \pm 18 MeV$ with the Clover action.

hep-lat↗