Experimental Test of Baryon Conservation: A New Limit on the Nucleon Lifetime

Abstract

The result of a search for nucleon decay using a 300-ton water Čerenkov detector located in the Homestake gold mine is reported. The nucleon total lifetime is found to be $T_N>3\mathrm{}\times {10}^{31}{B}_{\mu }$ yr, where $B_{\mu }$ is the model-dependent probability for production and detection of a decaying muon following a nucleon decay event. In the SU(5) grand unified model, published calculations of $B_{\mu }$ vary from 5% to 10%, thereby yielding nucleon total lifetime limits in the range (1.5-3)×${10}^{30}$ yr.