Measurement of the form-factor ratios for D_s^+ -> phi ell^+ nu_ell

TL;DR

This paper reports the measurement of form factor ratios in the decay D_s^+ -> phi ell^+ nu_ell, providing insights into the decay dynamics and contributing to the understanding of charm semileptonic decays.

Contribution

The study presents the first combined measurement of the form factor ratios r_V and r_2 for D_s^+ -> phi ell^+ nu_ell decay using data from Fermilab's E791 experiment.

Findings

Measured r_V = 2.27 ± 0.35 ± 0.22

Measured r_2 = 1.57 ± 0.25 ± 0.19

Combined results improve understanding of charm semileptonic decay form factors

Abstract

We have measured the form factor ratios r_V = V(0)/A_1(0) and r_2 = A_2(0)/A_1(0) for the decay D_s^+ -> phi ell^+ nu_ell, phi -> K^+ K^-, using data from charm hadroproduction experiment E791 at Fermilab. Results are based on 144 signal and 22 background events in the electron channel and 127 signal and 34 background events in the muon channel. We combine the measurements from both lepton channels to obtain r_V = 2.27 +- 0.35 +- 0.22 and r_2 = 1.57 +- 0.25 +- 0.19.