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 ${\tau }_{\overline{p}}>10.2a$ 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. (paper)