$B_c$ decays from highly improved staggered quarks and NRQCD

Abstract

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 $O({\alpha }_s)$ 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 $B\to D^{\ast }$.

arXiv comment6 pages, 5 figures. Talk presented at the 34th annual International Symposium on Lattice Field Theory, 24-30 July 2016, University of Southampton, UK

References in corpus (9)

• Evidence for an excess of B -> D(*) Tau Nu decays
• Measurement of the branching ratio of $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to $\bar{B}\to D^{(\ast )}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with hadronic tagging at Belle
• Measurement of the ratio of branching fractions $\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\tau }^{-}{\overline{\nu }}_{\tau })/\mathcal{B}({\overline{B}}^0\to D^{\ast +}{\mu }^{-}{\overline{\nu }}_{\mu })$
• Measurement of the branching ratio of ${\bar{B}}^0\to D^{\ast +}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to ${\bar{B}}^0\to D^{\ast +}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with a semileptonic tagging method
• Scaling studies of QCD with the dynamical HISQ action
• Heavy meson masses and decay constants from relativistic heavy quarks in full lattice QCD
• Precision tests of the J/ψ from full lattice QCD: mass, leptonic width and radiative decay rate to η_c
• Measurement of the $B_c^{+}$ meson lifetime using $B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu }X$ decays
• Matching lattice and continuum axial-vector and vector currents with NRQCD and HISQ quarks

Cited by in corpus (3)

• Review of Lepton Universality tests in B decays
• Model-Independent Determination of $B_c^{+}\to {\eta }_c{\ell }^{+}\nu$ Form Factors
• A model to accommodate the $B$-physics anomalies