Improved limit on the directly measured antiproton lifetime

Continuous monitoring of a cloud of antiprotons stored in a Penning trap for 405 days enables us to set an improved limit on the directly measured antiproton lifetime. From our measurements we extract a storage time of $3.15\times {10}^{8}$ equivalent antiproton-seconds, resulting in a lower lifetime limit of ${\tau }_{\bar{{\rm{p}}}}\gt 10.2\,{\rm{a}}$ with a confidence level of $68 \% $. This result improves the limit on charge-parity-time violation in antiproton decays based on direct observation by a factor of 7.