Inclusive Production of frame00 Mesons in CC and CCu Collisions
at an Incident Momentum of 4.5 GeV/c per Nucleon

Kh. U. Abraamyan, A. S. Galoyan, V. M. Izyurov, M. N. Khachaturyan,
A. H. Khudaverdyan1), M. A. Kozhin, G. L. Melkumov, and A. P. Sapozhnikov

Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia

Received January 31, 1997

Abstract—The cross sections for the inclusive production of 0 mesons in the reactions C + C frame1 0 + x and
C + Cu frame2 0 + x at an incident momentum of 4.5 GeV/c are measured as functions of the cumulative number X.
From the ratio of the observed cross sections for 0 production on carbon and copper targets in the interval
0.9< equalX < equal 1.9, the exponent in the cross-section parametrization Ed 3/d 3p ~ frame3 is derived to be n = 0.38 ± 0.03.
Under the assumption that the invariant cross section as a function of the projectile atomic number AP can be
parametrized in the form Ed 3/d 3p ~ frame4, the X and frame5 dependences of the exponent m are investigated by
comparing the cross sections for the reactions C + AT frame6 0 + x (AT = C, Cu) with those for the analogous
reactions induced by incident particles. At X = 1.9, the parameter m is found to reach a value of 2.1 ± 0.1. In
the kinematical region specified by the inequalities < equal 16frame7 and E > equal 2 GeV, the AP dependence of the cross
section under study shows a significant variation with X and only a weak variation with the pion transverse
momentum. The probabilities of the formation of six-quark configurations in 4He and 12C nuclei are estimated
at 5% and 20%, respectively. For the parametrization Ed 3/d 3p ~ exp(frame8X/X0), the values of the slope parameter
X0 corresponding to various energies of helium and carbon projectiles are compared. The energy at which the
cross section reaches the scaling regime corresponding to a plateau in the energy dependence of the parameter
X0, which characterizes the quark–parton structure function of the nucleus, is found to increase with increasing
atomic weight of the nucleus undergoing fragmentation.

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