Measurement of the Ratio of the Vector to Pseudoscalar Charm Semileptonic Decay Rate \Gamma(D+ > ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)

TL;DR

This paper measures the ratio of vector to pseudoscalar charm semileptonic decay rates using high-statistics data, providing new insights into decay dynamics and branching fractions.

Contribution

It presents the first precise measurement of the ratio aa(D+ aa K*0 mu+ nu)/aa(D+ aa K0 mu+ nu) using Fermilab data, refining previous estimates.

Findings

Measured aa(D+ aa K*0 mu+ nu)/aa(D+ aa K0 mu+ nu) = 0.594 b1 0.043 b1 0.033

Found the ratio for aa(D+ aa K0 mu+ nu)/aa(D+ aa K- pi+ pi+) close to 1.02

Indicates the world average branching fractions for D+ aa K0 mu+ nu are lower than previously reported.

Abstract

Using a high statistics sample of photo-produced charm particles from the FOCUS experiment at Fermilab, we report on the measurement of the ratio of semileptonic rates \Gamma(D+ > ANTI-K pi mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)= 0.625 +/- 0.045 +/- 0.034. Allowing for the K pi S-wave interference measured previously by FOCUS, we extract the vector to pseudoscalar ratio \Gamma(D+ > ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)= 0.594 +/- 0.043 +/- 0.033 and the ratio \Gamma(D+ > ANTI-K0 mu+ nu)/\Gamma(D+ > K- pi+ pi+)= 1.019 +/- 0.076 +/- 0.065. Our results show a lower ratio for \Gamma(D > K* \ell nu})/\Gamma(D > K \ell nu) than has been reported recently and indicate the current world average branching fractions for the decays D+ >ANTI-K0(mu+, e+) nu are low. Using the PDG world average for B(D+ > K- pi+ pi+) we extract B(D+ > ANIT-K0 mu+ nu)=(9.27 +/- 0.69 +/- 0.59 +/- 0.61)%.