Precision measurement of the ratio of the Λ b 0 to B ˉ 0 lifetimes

摘要

The LHCb measurement of the lifetime ratio of theΛb0baryon to theBˉ0meson is updated using data corresponding to an integrated luminosity of 3.0 fb?1collected using 7 and 8 TeV centre-of-mass energyppcollisions at the LHC. The decay modes used areΛb0→J/ψpK?andBˉ0→J/ψπ+K?, where theπ+K?mass is consistent with that of theKˉ?0(892)meson. The lifetime ratio is determined with unprecedented precision to be0.974±0.006±0.004, where the first uncertainty is statistical and the second systematic. This result is in agreement with original theoretical predictions based on the heavy quark expansion. Using the current world average of theBˉ0lifetime, theΛb0lifetime is found to be1.479±0.009±0.010?ps.