D0-D0bar Mixing in FOCUS

TL;DR

This paper reports a direct measurement of D0-D0bar mixing parameter y using lifetime differences in specific decay modes, providing new limits on mixing parameters and decay branching ratios based on a large charm meson sample from the FOCUS experiment.

Contribution

First direct measurement of the D0-D0bar mixing parameter y using lifetime differences in specific decay channels.

Findings

Measured y = (3.42 ± 1.39 ± 0.74)%

Observed branching ratio R = (0.404 ± 0.085 ± 0.025)%

Set limits on mixing parameters x' and y' and on doubly Cabibbo suppressed decay rate R_DCS.

Abstract

We report on a direct measurement of the mixing parameter y=(3.42+-1.39+-0.74)% in the D0-D0bar system by measuring the lifetime difference between the CP mixed final state K^+pi^- and the CP even state K^+K^-. We also present a study of the decay \ws based on a sample of 149+-31 observed events compared to 36760+-195 events observed in the Cabibbo favored channel D0->K^-pi^+. The observed branching ratio R=(0.404+-0.085+-0.025)% is used to obtain limits on the mixing parameters x' and y' and the doubly Cabibbo suppressed branching ratio, R_DCS. These studies are based on a large sample of photoproduced charm mesons from the FOCUS experiment at Fermilab (FNAL-E831).