Study of inclusive baryon - anti-baryon pair production of P or Lambda in two photon processes

The VENUS collaboration Uehara, S. ; Abe, K. ; Amako, K. ; et al.
Z.Phys.C 69 (1996) 597-606, 1996.
Inspire Record 400152 DOI 10.17182/hepdata.38341

Inclusive baryon-antibaryon pair production was studied in two-photon events which were collected at the e+e− collider TRISTAN, and correspond to an integrated luminosity of 303 pbt?1. Correlations between a baryon and an antibaryon were studied for their flavors (p or Λ) and their momentum vectors. The experimental results were compared with the expectations from a jet-fragmentation Monte Carlo simulation. We have found that although the ratios of the cross sections of different baryon-flavor combinations are consistent with the Monte Carlo expectations, the cross section shows an excess over the Monte Carlo expectation in a low invariant-mass region of final-state particles at large angles, that indicates a significant contribution from higher-order QCD or non-perturbative effects. The experimental data show no narrow azimuthal-angle correlation, which is expected from a jet-fragmentation Monte Carlo. A search for exclusive Λ pair production has also been made. We have no candidates and have obtained the upper limit for the cross section.

4 data tables

Topological cross section for events in anti-tagged two photon processes.

Ratios of cross sections. Here 'p' includes the protons from the decay of any hadrons, except for lambdas. 'lambda' includes all decay products.

Upper limits (95% CL) assuming shape of the W dependence is W**(-12)(BETA*(LAMBDA)) where BETA*(LAMBDA) is the velocity of the LAMBDA in the c.m. frame of the gamma-gamma.

More…