On the D^*_s and charmonia leptonic decays

¹ Laboratoire de Physique de Clermont, Campus Universitaire des Cézeaux, 4 Avenue Blaise Pascal, TSA 60026, 63171 Aubière Cedex, France
² Laboratoire de Physique Théorique, CNRS, Univ. Paris-Sud et Université Paris-Saclay, Bâtiment 210, 91405 Orsay Cedex, France
³ Institut für Theoretische Physik, Universität Münster, Wilhelm-Klemm-Str. 9, 48149 Münster, Germany

^* Speaker, e-mail: benoit.blossier@th.u-psud.fr

Published online: 26 March 2018

Abstract

Among the different scenarios of New Physics, those with an extended Higgs sector are examined with a lot of attention. Recent experimental observations of several anomalies in flavour physics with respect to expectations of the Standard Model further motivate the effort of phenomenologists. First, informations about the R_Ds ratio, a test of lepton flavour universality equivalent to R_D, already measured, but with the s quark as spectator, are awaited in coming years to constrain the corner of an extended Higgs sector with charged doublets. On another side, leptonic widths of pseudoscalar quarkonia are particularly interesting to test an extended Higgs sector with a light CP-odd Higgs boson singlet, through the study of its mixing with quarkonia states. Hadronic parameters entering those processes have to be determined from lattice QCD with enough confidence on the control of systematic errors. We report on the very first step of a long-term program tackled with N_f = 2 Wilson-Clover fermions to put relevant constraints on extensions of the Higgs sector: extraction of decay constants of D^*_s, ƞ_c, ƞ_c (2S), J/Ψ and Ψ(2S) with lattice ensembles provided by the CLS effort, considering 2 lattice spacings and a large range of pion masses to estimate cut-off effects and extrapolate results to the chiral limit.