Studies of the Cabbibo-Suppressed Decays $D^+ \to \pi^0 \ell^+ \nu$ and $D^+ \to \eta e^+ \nu_e$

TL;DR

This study measures the branching fractions of Cabibbo-suppressed and related decays of D+ mesons using CLEO II data, providing insights into decay dynamics and form factor ratios.

Contribution

It reports the first measurement of the branching fraction for D+ to pi0 l+ nu relative to D+ to K0 l+ nu and sets an upper limit for D+ to eta e+ nu decay.

Findings

Branching fraction for D+ to pi0 l+ nu is 0.046±0.014±0.017.

The ratio of form factors |f+^{π}(0)/f+^{K}(0)|^2 is 0.9±0.3±0.3.

Upper limit for D+ to eta e+ nu branching ratio is 1.5 times that of D+ to pi0 e+ nu.

Abstract

Using 4.8 fb$^{-1}$ of data taken with the CLEO II detector, the branching fraction for the Cabibbo-suppressed decay $D^+\to\pi^0\ell^+\nu$ measured relative to the Cabibbo favored decay $D^+\to\bar{K^0}\ell^+\nu$ is found to be $0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity constraints, we determine $| f_+^{\pi}(0)/f_+^K(0)|^2=0.9\pm 0.3\pm 0.3$ We also present a 90% confidence level upper limit for the branching ratio of the decay $D^+ \to \eta e^+\nu_e$ relative to that for $D^+ \to \pi^0 e^+\nu_e$ of 1.5.