New methods for B decay constants and form factors from Lattice NRQCD

¹ SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
² Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA
³ Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, CB3 0WA, UK
⁴ Institute for Nuclear Theory, University of Washington, Seattle, Washington 98195, USA
⁵ New High Energy Theory Center and Department of Physics and Astronomy, Rutgers, the State University of New Jersey, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA

^* Speaker, e-mail: christine.davies@glasgow.ac.uk

Published online: 26 March 2018

Abstract

We determine the normalisation of scalar and pseudo scalar current operators made from NonRelativistic QCD (NRQCD) b quarks and Highly Improved Staggered (HISQ) light quarks through O(α_s∧_QCD/m_b). We use matrix elements of these operators to extract B meson decay constants and form factors and compare to those obtained using the standard vector and axial vector operators. We work on MILC second-generation 2+1+1 gluon field configurations, including those with physical light quarks in the sea. This provides a test of systematic uncertainties in these calculations and we find agreement between the results to the 2% level of uncertainty previously quoted.