Diffractive dissociation of a π− meson on a proton in π−p interactions at an incident momentum of 40 GeV/ c

This paper presents the results of a new study of diffractive dissociation of an incident negative pion on a target proton at an incident momentum of 40[Formula: see text]GeV/c. Diffractive-type events have been selected using criteria based on the effective target mass, missing mass and transferred four-momentum [Formula: see text], taking into account the losses due to the detection momentum threshold for slow protons. It is shown that the [Formula: see text]-distribution is described well by an exponential dependence with a slope, [Formula: see text][Formula: see text]GeV[Formula: see text], which is practically independent of the final-state multiplicity. Cross-sections for diffractive dissociation of a negative pion were measured for different topologies, i.e., for events with different numbers of charged particles in the final state. The total cross-section for diffractive dissociation of a negative pion in [Formula: see text] interactions at 40[Formula: see text]GeV/c has proved to be [Formula: see text] mb, which coincides within uncertainties with that ([Formula: see text] mb) found earlier in [Formula: see text] interactions at 205[Formula: see text]GeV/c, indicating its collision energy independence in the studied energy range. The largest contribution to diffractive dissociation of a negative pion has been observed in the channel with four charged particles in the final state. The average number of charged particles per collision event in diffractive dissociation events of a negative pion in [Formula: see text] interactions at 40[Formula: see text]GeV/c has been found to be [Formula: see text]. The obtained results refine the characteristics of diffractive processes in [Formula: see text] interactions and confirm the universality of cross-section parameters and the slope of the [Formula: see text]-distribution over a wide energy range.