# ${{\overline{\boldsymbol p}}}/{{\boldsymbol p}}$ CHARGE-TO-MASS RATIO, $\vert {\boldsymbol q_{{{\overline{\boldsymbol p}}}}\over {\boldsymbol m}_{{{\overline{\boldsymbol p}}}}}\vert /({\boldsymbol q_{{{\boldsymbol p}}}\over {\boldsymbol m}_{{{\boldsymbol p}}}}$) INSPIRE search

A test of $\mathit CPT$ invariance. Listed here are measurements involving the $\mathit inertial$ masses. For a discussion of what may be inferred about the ratio of ${{\overline{\mathit p}}}$ and ${{\mathit p}}$ $\mathit gravitational$ masses, see ERICSON 1990 ; they obtain an upper bound of $10^{-6}-10^{-7}$ for violation of the equivalence principle for ${{\overline{\mathit p}}}$'s.
VALUE DOCUMENT ID TECN  COMMENT
$1.000000000001$ $\pm0.000000000069$
 2015
TRAP Penning trap
• • • We do not use the following data for averages, fits, limits, etc. • • •
$0.99999999991$ $\pm0.00000000009$
 1999
TRAP Penning trap
$1.0000000015$ $\pm0.0000000011$ 1
 1995
TRAP Penning trap
$1.000000023$ $\pm0.000000042$ 2
 1990
TRAP Penning trap
1  Equation (2) of GABRIELSE 1995 should read $\mathit M({{\overline{\mathit p}}})/\mathit M({{\mathit p}}$) = $0.999~999~995~$(11) (G.$~$Gabrielse, private communication).
2  GABRIELSE 1990 also measures ${\mathit m}_{{{\overline{\mathit p}}}}/{\mathit m}_{{{\mathit e}^{-}}}$ = $1836.152660$ $\pm0.000083$ and ${\mathit m}_{{{\mathit p}}}/{\mathit m}_{{{\mathit e}^{-}}}$ = $1836.152680$ $\pm0.000088$. Both are completely consistent with the 1986 CODATA (COHEN 1987 ) value for ${\mathit m}_{{{\mathit p}}}/{\mathit m}_{{{\mathit e}^{-}}}$ of $1836.152701$ $\pm0.000037$.
References:
 ULMER 2015
NAT 524 196 High-Precision Comparison of the Antiproton-to-Proton Charge-to-Mass Ratio
 GABRIELSE 1999
PRL 82 3198 Precision Mass Spectroscopy of the Antiproton and Proton Using Simultaneously Trapped Particles
 GABRIELSE 1995
PRL 74 3544 Special Relativity and the Single Antiproton: Fortyfold Improved Comparison of ${{\overline{\mathit p}}}$ and ${{\mathit p}}$ Charge-to-Mass Ratios
 GABRIELSE 1990
PRL 65 1317 A 1000 $−$ Fold Improvement in the Measured Antiproton Mass