Experimental estimation of the charm-production cross section in pp interactions at 70 GeV/c with the aid of the SVD setup

Abstract

Charmed-particle production in pp interactions at 70 GeV/c was studied with the SVD setup at the IHEP accelerator (Protvino). The experimental procedure used and the data-selection
methods are described. Data obtained by using a quickly cycling bubble chamber and a magnetic spectrometer are analyzed. The
number of inelastic-interaction events recorded in the chamber is 109000, with the charge multiplicity being n
ch/4. The corresponding statistics are 4.96 event/µb. Part of the events were recorded in the magnetic spectrometer. Three three-prong
decays of charged particles near the primary vertex are found on the films, two of these being recorded with the spectrometer.
All three are interpreted as D
− decays. Two neutral decays observed simultaneously in the chamber and in the spectrometer are interpreted as
[`(D)]0\bar D^0
decays. The total cross section for
c[`(c)]c\bar c
production in the Feynman variable region −1<x
F<+1 is estimated at
s(c[`(c)]) = 1.6 - 0.7 + 1.1 (stat.) ±0.3(syst.)mb\sigma (c\bar c) = 1.6_{ - 0.7}^{ + 1.1} (stat.) \pm 0.3(syst.)\mu b
. The cross-section values and the mean values 〈|x
F|〉 and 〈p⊥〉 for D mesons are compared with other experimental results in the energy range 58–800 GeV. The data of this experiment are compatible
with the cross-section estimates obtained in the beam-dump experiment at 70 GeV and with those predicted by perturbative QCD.