Toward accurate form factors for B-to-light meson decay from lattice QCD

Parrott, W.G., Bouchard, C. , Davies, C.T.H. and Hatton, D. (2021) Toward accurate form factors for B-to-light meson decay from lattice QCD. Physical Review D, 103(9), 094506. (doi: 10.1103/PhysRevD.103.094506)

Abstract

We present the results of a lattice QCD calculation of the scalar and vector form factors for the unphysical B s → η s decay, over the full physical range of q 2 . This is a useful testing ground both for lattice QCD and for our wider understanding of the behavior of form factors. Calculations were performed using the highly improved staggered quark (HISQ) action on N f = 2 + 1 + 1 gluon ensembles generated by the MILC Collaboration with an improved gluon action and HISQ sea quarks. We use three lattice spacings and a range of heavy quark masses from that of charm to bottom, all in the HISQ formalism. This permits an extrapolation in the heavy quark mass and lattice spacing to the physical point and nonperturbative renormalization of the vector matrix element on the lattice. We find results in good agreement with previous work using nonrelativistic QCD b quarks and with reduced errors at low q 2 , supporting the effectiveness of our heavy HISQ technique as a method for calculating form factors involving heavy quarks. A comparison with results for other decays related by SU(3) flavor symmetry shows that the impact of changing the light daughter quark is substantial but changing the spectator quark has very little effect. We also map out form factor shape parameters as a function of heavy quark mass and compare to heavy quark effective theory expectations for mass scaling at low and high recoil. This work represents an important step in the progression from previous work on heavy-to-heavy decays ( b → c ) to the numerically more challenging heavy-to-light decays.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hatton, Dr Daniel and Davies, Professor Christine and Parrott, Mr William and Bouchard, Dr Chris
• Authors: Parrott, W.G., Bouchard, C., Davies, C.T.H., and Hatton, D.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Physical Review D
• Publisher: American Physical Society
• ISSN: 2470-0010
• ISSN (Online): 2470-0029
• Published Online: 13 May 2021
• Copyright Holders: Copyright © 2021 American Physical Society
• First Published: First published in Physical Review D 103(9): 094506
• Publisher Policy: Reproduced under a Creative Commons License