文章基本信息

标题：decays from highly improved staggered quarks and NRQCD
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作者：A.Lytle ; B.Colquhoun ; C.Davies 等
期刊名称：PoS - Proceedings of Science
印刷版ISSN：1824-8039
出版年度：2016
卷号：256
DOI：10.22323/1.256.0281
语种：English
出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We calculate semileptonic form factors for the decays $B_c \to \eta_c \, l \nu$ and $B_c \to J/\psi \, l \nu$ over the entire $q^2$ range, using a highly improved lattice quark action for charm at several lattice spacings down to $a=0.045~$fm. We have two ways of treating the $b$ quark: either with an $\cal O(\alpha_s)$ improved NRQCD formalism or by extrapolating a heavy mass $m_h$ to $m_b$ in the relativistic formalism. Comparison of the two approaches provides an important cross-check of methodologies in lattice QCD. Nonperturbative renormalisation of the currents in the relativistic theory also allows us then to fix NRQCD-charm normalisation for $b$ to $c$ decays such as $B \to D$ and $B \to D^*$.