Measurement of the Omega_c Lifetime

TL;DR

This paper reports the measurement of the Omega_c baryon's lifetime using multiple decay modes and data samples, demonstrating its status as the shortest-lived weakly decaying particle observed and confirming theoretical lifetime patterns.

Contribution

First measurement of Omega_c lifetime using independent decay modes and data samples, employing a novel continuous maximum likelihood method without topological cuts.

Findings

Omega_c lifetime = 55 +13-11(stat) +18-23(syst) fs

Omega_c is the shortest-lived weakly decaying particle observed

Results support the predicted charmed baryon lifetime pattern

Abstract

We present the measurement of the lifetime of the Omega_c we have performed using three independent data samples from two different decay modes. Using a Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts normally used in charm analysis. The short but measurable lifetime of the Omega_c is demonstrated by a clear enhancement of the signals at short but finite decay lengths. Using a continuous maximum likelihood method we determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs. This makes the Omega_c the shortest living weakly decaying particle observed so far. The short value of the lifetime confirms the predicted pattern of the charmed baryon lifetimes and demonstrates that the strong interaction plays a vital role in the lifetimes of charmed hadrons.