F. Abe et al., CENTER-OF-MASS ANGULAR-DISTRIBUTION OF PROMPT PHOTONS PRODUCED IN P(P)OVER-BAR COLLISIONS AT ROOT-S = 1.8-TEV, Physical review letters, 71(5), 1993, pp. 679-683
Data taken with the Collider Detector at Fermilab (CDF) during the 198
8-1989 run of the Tevatron are used to measure the distribution of the
center-of-mass (rest frame of the initial state partons) angle betwee
n isolated prompt photons and the beam direction. The shape of the ang
ular distribution for photon-jet events is found to be significantly d
ifferent from that observed in dijet data. The QCD predictions show qu
alitative agreement with the observed prompt photon angular distributi
on.