Charm lifetime

Abstract

A review of the charmed meson and baryon lifetimes is presented. Our knowledge of charmed particle lifetimes has greatly improved over the past two years, a crucial rôle having been played by the E687 experiment at Fermilab, which has almost quadrupled the samples of $D$ mesons. The lifetime ratios $\tau (D^{+})/\tau (D^0)$ and $\tau (D_s^{+})/\tau (D^0)$ are now known with an accuracy of 1.7\% and 3.7\% respectively. In the baryon sector the statistics is still limited, but the experimental results on ${\Lambda }_c^{+}$, ${\Xi }_c^0$ and ${\Xi }_c^{+}$ exhibit a clear pattern of lifetime hierarchy, as expected from simple theoretical arguments. The first measurement of $\tau ({\Omega }_c^0)$ from E687 is also presented to complete the charmed baryon lifetime picture. The more accurate experimental scenario can provide information on non-perturbative QCD effects and the hadronic matrix elements.

Comments: 10 pages, latex, 3 figures. Talk presented at the 6th. International Symposium on Heavy Flavour Physics (Pisa, June 1995)