First Measurement of the D*+ Width

TL;DR

This paper reports the first measurement of the D*+ meson width using e+e- collision data, employing advanced tracking and beam spot techniques to analyze decay energy release.

Contribution

It introduces a novel measurement of the D*+ width with a unique method leveraging the small beam spot size for improved accuracy.

Findings

Measured Gamma(D*+) = 96 +- 4 (stat) +- 22 (syst) keV

First direct measurement of D*+ width

Demonstrates effectiveness of beam spot-based reconstruction

Abstract

We have made the first measurement of the D*+ width using 9/fb of e+e- data collected near the Y4S resonance by the CLEO II.V detector. Our method uses advanced tracking techniques and a reconstruction method that takes advantage of the small vertical size of the CESR beam spot to measure the energy release distribution from the D*+ -> D0 pi+ decay. Our preliminary result is Gamma(D*+) = 96 +- 4 (Statistical) +- 22 (Systematic) keV.