Search for charmed particle production in proton-proton collisions at the CERN-ISR. [53 GeV (c. m. )

Abstract

Experimental results on a search for charmed particle production in proton-proton collisions at the center of mass energy (..sqrt..s) of 53 GeV are presented. Evidence of cidences, a signature of charmed particle production, was sought. The inclusive e/..pi.. ratio was measured with a magnetic spectrometer located at 32/sup 0/ from Beam 1 of Intersection I6 of the CERN Intersecting Storage Rings (ISR). The e/..pi.. ratio from direct (unknown) sources was found to rise from 1.06 x 10/sup -4/ at p/sub perpendicular to/ = 1.5 GeV/c to 5.53 x 10/sup -4/ at p/sub perpendicular to/ = 0.25 GeV/c. One possible source for this signal is the semi-leptonic decay of charmed particles (e.g., D ..-->.. K/sup 0/ e..nu..). If so, then electron-strange particle (e.g., ..lambda../sup 0/,K/sup 0/) coincidences are expected. The charged decay products of ..lambda../sup 0/ and K/sup 0/ were detected in a multiparticle spectrometer surrounding Beam 1 downstream of the intersection. To determine if there is an electron-strange particle correlation, the number of ..lambda../sup 0/'s (K/sup 0/'s) in coincidence with an electron in the 32/sup 0/ spectrometer was compared with the number of ..lambda..'s (K/sup 0/'s) in coincidence with a hadron in the same kinematic range. No evidence for an enhanced production of strange particles with electrons relative to hadrons was found. However, given the acceptance of the apparatus, the absence of a signal is consistent with current models of charmed particle production and decay. 40 references, 51 figures, 20 tables.