Isospin breaking in the decay constants of heavy mesons from QCD sum rules

Author(s)
Wolfgang Lucha, Dmitri Melikhov, Silvano Simula
Abstract

We present a study of the strong isospin-breaking (IB) effect, due in QCD to the difference between u- and d-quark masses, in the leptonic decay constants of charmed and beauty pseudoscalar and vector mesons using the method of QCD sum rules. We apply the sum-rule analysis to the decay constants of mesons containing one heavy quark and one light quark with the light mass in the range from the average u/d quark mass to the strange-quark mass. We then analyse the dependence of the decay constants on the light-quark mass and extract with good accuracy the IB ratios of decay constants at leading order in the mass difference (m(d) - m(u)), obtaining: (f(D)+ - fD(0))/fD = 0.0047(6), (f(D*+) - f(D*o))/fD* = 0.0068(9), (fB(0) - f(B+))/f(B) = 0.0047(6), and (f(B*0) - f(B*+))/f(B*) = 0.0045(5), which yield: f(D+) - f(D0) = 0.97 +/- 0.13 MeV, f(D*+) - f(D*0) = 1.73 +/- 0.27 MeV, f(B0) - f(B+) = 0.90 +/- 0.13 MeV, f(B*0) - f(B*+) = 0.81 +/- 0.11 MeV. In the case of the D-meson our finding is consistent with recent lattice QCD results, whereas it is much lower in the case of the B-meson showing a tension of approximate to 3 standard deviations. (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.

Organisation(s)
Particle Physics
External organisation(s)
Österreichische Akademie der Wissenschaften (ÖAW), Lomonosov Moscow State University (MSU), Universität Wien, Istituto Nazionale di Fisica Nucleare (INFN), Roma
Journal
Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume
765
Pages
365-370
No. of pages
6
ISSN
0370-2693
DOI
https://doi.org/10.1016/j.physletb.2016.12.041
Publication date
02-2017
Peer reviewed
Yes
Austrian Fields of Science 2012
103012 High energy physics
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/isospin-breaking-in-the-decay-constants-of-heavy-mesons-from-qcd-sum-rules(4a6248e4-3c83-4e32-acb6-7d5235c04008).html