Precise determination of the lifetime of the charmed baryon Λc

Abstract We present the final result on the measurement of the lifetime of the Λ c -baryon from a sample of Λ c -decays obtained in the NA32 experiment at the CERN SPS using silicon microstrip detectors and charge-coupled devices for vertex reconstruction. We observe a total of 160 Λ c in five different decay modes. A sample of 101 unambiguous decays of Λ c →pK − π + (and charge conjugate) above a background of 7 events is used for the Λ c mass and lifetime measurement. The mean Λ c lifetime is determined to be 1.96 −0.20 +0.23 ×10 −13 s and the Λ c mass to be 2285.8±0.6±1.2 MeV/ c 2 .