Bs → Ds l ν Form Factors and the Fragmentation Fraction Ratio fs / fd

Monahan, C. J., Na, H., Bouchard, C. M. , Lepage, G. P. and Shigemitsu, J. (2017) Bs → Ds l ν Form Factors and the Fragmentation Fraction Ratio fs / fd. Physical Review D, 95(11), 114506. (doi: 10.1103/PhysRevD.95.114506)

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Abstract

We present a lattice quantum chromodynamics determination of the scalar and vector form factors for the Bs → Ds l ν decay over the full physical range of momentum transfer. In conjunction with future experimental data, our results will provide a new method to extract |Vcb|, which may elucidate the current tension between exclusive and inclusive determinations of this parameter. Combining the form factor results at non-zero recoil with recent HPQCD results for the B → Dlν form factors, we determine the ratios f0(Bs→Ds)(q^2=Mπ^2)/f0(B→D)(q^2=MK^2) = 1.000(62) and f0(Bs→Ds)(q^2=Mπ^2)/f0(B→D)(q^2=Mπ^2) = 1.006(62). These results give the fragmentation fraction ratios fs / fd = 0.310(30)stat.(21)syst.(6)theor.(38)latt. and fs / fd = 0.307(16)stat.(21)syst.(23)theor.(44)latt., respectively. The fragmentation fraction ratio is an important ingredient in experimental deter- minations of Bs meson branching fractions at hadron colliders, in particular for the rare decay B(Bs → μ+μ−). In addition to the form factor results, we make the first prediction of the branching fraction ratio R(Ds) = B(Bs → Ds τ ν)/B(Bs → Ds l ν) = 0.301(6), where l is an electron or muon. Current experimental measurements of the corresponding ratio for the semileptonic decays of B mesons disagree with Standard Model expectations at the level of nearly four standard deviations. Future experimental measurements of R(Ds) may help understand this discrepancy.

Item Type:Articles (Letter)
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Bouchard, Dr Chris
Authors: Monahan, C. J., Na, H., Bouchard, C. M., Lepage, G. P., and Shigemitsu, J.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review D
Publisher:American Physical Society
ISSN:1550-7998
ISSN (Online):1550-2368
Published Online:16 June 2017
Copyright Holders:Copyright © 2017 American Physical Society
First Published:First published in Physical Review D 95(11): 114506
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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