Study of the semileptonic decay Ds+ -> f0(980) e+ nu and implications for Bs -> J/psi f0

TL;DR

This study measures semileptonic decay rates of Ds+ mesons to f0(980) and phi, compares their ratios to B meson decay ratios, and discusses implications for CP violation measurements in Bs mesons.

Contribution

It provides the first measurement of the ratio of decay rates involving f0(980) and phi in Ds+ decays and explores their implications for CP violation studies in Bs mesons.

Findings

Measured the ratio of decay rate derivatives at q^2=0 to be (42 +/- 11)%

Determined the f0 mass and width as (977 +11/-9) MeV and (91 +30/-22) MeV

Updated branching fractions for Ds+ decays to f0(980) e+ nu and phi e+ nu

Abstract

Using e+e- -> Ds^-Ds^{*+} and Ds^{*-}Ds^+ interactions at 4170 MeV collected with the CLEO-c detector, we investigate the semileptonic decays Ds+ -> f0(980) e+ nu, and Ds+ -> phi e+ nu. By examining the decay rates as functions of the four-momentum transfer squared, q^2, we measure the ratio [dB/dq^2(Ds+ -> f0(980) e+ nu) B(f0 -> pi+pi-)]/[dB/dq^2(Ds+ -> phi e+ nu)B(phi -> K+K-)] at q^2 of zero to be (42 +/- 11)%. This ratio has been predicted to equal the rate ratio [B(Bs -> J/psi f_0)B(f0 -> pi+pi-)]/[B(Bs -> J/psi phi)B(phi -> K+K-)], thus indicating that the CP eigenstate J/psi f0 could be useful for measuring CP violation via Bs mixing. Assuming a simple pole model for the form factor |f+(q^2)| in the f0 e+ nu decay, we find a pole mass of (1.7 {+4.5} {-0.7} +/- 0.2) GeV. We also determine the f0 mass and width as (977 {+11}{-9} +/- 1) MeV, and (91{+30}{-22}+/- 3) MeV, respectively. In addition, we present updated results for B(Ds+ -> f0(980) e+ nu) B(f0 -> pi+pi-)=(0.20 +/- 0.03 +/- 0.01)%, and B}(Ds+ -> phi e+ nu)=(2.36 +/- 0.23 +/- 0.13)%.