Study of D0-Dbar0 mixing and D0 doubly cabibbo-suppressed decays

TL;DR

This study analyzes D0-Dbar0 mixing and doubly Cabibbo-suppressed decays using ALEPH data, providing limits on mixing rates and measuring decay ratios to enhance understanding of charm meson behavior.

Contribution

It presents the first measurement of the relative branching ratio for D0 decays and sets an upper limit on D0-Dbar0 mixing rate using proper-time distributions.

Findings

Measured B(D0 -> K+pi-)/B(D0 -> K-pi+) as (1.84+-0.59+-0.34)%

Set an upper limit on D0-Dbar0 mixing rate at 0.92% (95% CL)

Assessed the impact of interference effects on mixing measurements

Abstract

Using a sample of four million hadronic Z events collected in ALEPH from 1991 to 1995, the decays D*+ -> D0pi^+_s, with D0 decaying to K-pi+ or to K+pi-, are studied. The relative branching ratio B(D0 -> K+pi-)/B(D0 -> K-pi+) is measured to be (1.84+-0.59(stat.)+-0.34(syst.))%. The two possible contributions to the D0 -> K+pi- decay, doubly cabibbo-suppressed decays and D0-Dbar0 mixing, are disentangled by measuring the proper-time ditribution of the reconstructed D0's. Assuming no interference between the two processes, the upper limit obtained on the mixing rate is 0.92% at 95% CL. The possible effect of interference between the two amplitudes is also assessed.