arXiv:hep-lat/9905036·v1·High Energy Physics — Lattice

B meson leptonic decay constant with quenched lattice NRQCD

JLQCD Collaboration: K-I. Ishikawa🇯🇵 · N. Yamada🇯🇵 · S. Aoki🇯🇵 · M. Fukugita🇯🇵 · S. Hashimoto🇯🇵 · N. Ishizuka🇯🇵 · Y. Iwasaki🇯🇵 · K. Kanaya🇯🇵 · T. Kaneda🇯🇵 · S. Kaya🇯🇵 · Y. Kuramashi🇯🇵 · H. Matsufuru🇯🇵

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Abstract

We present a lattice NRQCD study of the B meson decay constant in the quenched approximation with emphasis given to the scaling behavior. The NRQCD action and the heavy-light axial current we use include all terms of order 1/M and the perturbative $O (α_{s} a)$ and $O (α_{s} / M)$ corrections. Using simulations at three value of couplings $β$ =5.7, 5.9 and 6.1 on lattices of size $1 2^{3} \times 32, 1 6^{3} \times 48$ and $2 4^{3} \times 64$ , we find no significant $a$ dependence in $f_{B}$ if the $O (α_{s} a)$ correction is included in the axial current. We obtain $f_{B} = 167 (7) (15)$ MeV, $f_{B_{s}} = 191 (4) (17) (_{- 0}^{+ 4})$ MeV and $f_{B_{s}} / f_{B} = 1.15 (3) (1) (_{- 0}^{+ 3})$ , with the first error being statistical, the second systematic, and the third due to uncertainty of strange quark mass, while quenching errors being not included.