Multiple high-precision measurement campaigns at CERN of the antiproton-to-proton charge-to-mass ratio—to a precision of 16 parts per trillion—in a cryogenic multi-Penning trap offer no evidence of charge–parity–time violation, and set stringent limits on the clock-weak-equivalence principle.
- M. J. Borchert
- J. A. Devlin
- S. Ulmer
