Search

Results are presented onK + p andK − p elastic scattering at 32.1 GeV/c in the |t| interval 0.06–1.4 GeV2. The samples contain approximately 15,000 events each and are obtained in the MIRABELLE bubble chamber at the Serpukhov accelerator. The |t| distributions are parametrized by quadratic exponential formsdσ/dt=A exp (bt+ct 2). The total elastic cross sections, obtained by integrating the fitted distributions, are (2.39±0.07) mb and (2.57±0.10) mb inK + p andK − p interactions, respectively. A cross-over between theK + p andK − p differential cross sections is found at |t c |=0.17±0.02 GeV2. The hypothesis of geometric scaling becomes valid somewhere between 32 and 70 GeV/c forK + p interactions, and is trivially verified forK − p scattering. Finally, an impact parameter analysis of the difference betweenK − p andK + p elastic amplitudes is presented.

Lambda production is studied in K − p interactions at 32 GeV/ c . The total Λ cross section is 2.31±0.03 mb . Using the measured Λγ combinations we find that (31±4)% of all Λ's are produced via the Σ 0 → Λγ decay. About 60% of the Λ's are associated with either a N N or K K pair; about 40% of the Λ's are produced through the hypercharge annihiltion reaction K − p→ Λ + π 'a. The two-peak structure of the invariant x distribution can be related to fragmentation processes. The Λ is found to be unpolarized in the target fragmentation region, whereas a transverse polarization is observed for forward produced Λ's. As a function of p ⊥, a polarization effect is measured at medium p ⊥.

An enhancement in the (K−π+) mass distribution at 1871 ± 10 MeV with full width of 285 ± 40 MeV is observed in the charge-exchange reaction K−p → K−π+n at 10 and 16 GeV/c. The energy dependence of its cross section, the shape of the differential cross section dσ/dt and the decay angular distributions are consistent with a production mechanism by pion exchange. No significant enhancement at the same mass is seen in the non-charge exchange reaction K−p → (Kπ)−p. The experimental evidence is reviewed and it is suggested that there may be more than one K∗ enhancement in the 1700–1900 mass region.