Possible Anomaly in Meson Production in p + d Collisions

Proton-deuterium interactions were studied for the possibility of detecting new particles. The He/sup 3/ momentum spectra were measured for incident proton energies of 624 to 743 Mev. The data were inconsistent with the relativistically invariant phase space assumed. The discrepancy appeared in the form of a narrow peak which kinematically behaved like a system with a mass or total energy of 310 plus or minus 10 Mev. The natural line width of this system was not more than 16 Mev. Plausible explanations of the line are the existence of a new neutral particle or a resonant pi - pi system. The possible isotopic spin assignments are I = 1 r I = 0. (M.C.G.)