($\vert {\boldsymbol q_{{{\overline{\boldsymbol p}}}}\over {\boldsymbol m}_{{{\overline{\boldsymbol p}}}}}\vert -{\boldsymbol q_{p}\over {\boldsymbol m}_{{{\boldsymbol p}}}})/{\boldsymbol q_{{{\boldsymbol p}}}\over {\boldsymbol m}_{{{\boldsymbol p}}}}$
INSPIRE search
A test of $\mathit CPT$ invariance. Taken from the ${{\overline{\mathit p}}}/{{\mathit p}}$ charge-to-mass ratio, above.