A search for prompt production of electrons in proton-Pt collisions at 19 GeV/c

Abstract

Production of positrons in p-Pt collisions at 19 GeV/ c has been observed in a previously reported experiment, performed to measure the mean life of the neutral pion, at p T = 0.54 GeV/ c, x = 0.26 and θ cm = 37°; however, unlike to similar measurements at higher energies, 30 to 1500 GeV/ c, the observed effect is demonstrated to be due to K → πe v decay and π O Dalitz decay. After substraction a ratio e +/ π + = −(0.2 ± 0.29) × 10 −4 is obtained. This first observation of energy dependence of the e π ratio is discussed.