A precision determination of the mass of the $\hat{I}\cdot$ meson

Abstract

Several processes of meson production in proton-deuteron collisions have been measured simultaneously using a calibrated magnetic spectrograph. Among these processes, the $\hat{I}\cdot$ meson is seen clearly as a sharp missing--mass peak on a slowly varying background in the $p+d{\to }^3\text{He}+X$ reaction. Knowing the kinematics of the other reactions with well determined masses, it is possible to deduce a precise mass for the $\hat{I}\cdot$ meson. The final result, $m(\hat{I}\cdot )=547.311\pm 0.028\text{(stat)}\pm 0.032{\text{(syst) MeV/c}}^2$, is significantly lower than that found by the recent NA48 measurement, though it is consistent with values obtained in earlier counter experiments.

10 pages, 6 figures, Fig. 3 changed