N. Yamdagni

Backward production of a spin parity 1+ϱπ enhancement at 1.04 GeV

Abstract A spin-parity 1 + ϱπ enhancement is observed for the 3π mass spectrum in the reaction K − p → Σ − π + π + π − where events with a small (K − → Σ − ) momentum transfer are selected. The mass (1040 MeV) and width (230 MeV) of this enhancement are reminiscent of the A 1 → ϱπ bump which has mainly been observed in the diffractive-like processes. The cross section for this enhancement at 4.15 GeV/ c incident K − momentum is (3.6 ± 0.5) μ b.

The reactions K+ m̊p → ΛX++ and K+ p → ΛX++ at incident momenta of 8.2 and 16.0 GeV/c

Inclusive production of Λ and Λ in K+ p interactions is studied at incident momenta of 8.2 and 16.0 GeV/c. Cross sections and single-particle distributions are presented, the correlation between longitudinal and transverse momentum is investigated, and the dependence of average charge multiplicity on missing mass measured. For Λ production, early scaling is observed in the target fragmentation region when the data are presented in terms of (M2-Mth2)/s and t, where Mth is the threshold value of the missing mass M. Furthermore, a triple-Regge analysis in these variable yields an effective exchange trajectory which passes through the K, Q and L mesons. There is evidence for beam fragmentation in Λ and Λ production, but the contributions seem not to be dominant in the fragmentation region. Nevertheless, the parameter values in a triple-Regge description are estimated, and together with those for target fragmentation in Λ production, provide a complete description of the fragmentation contributions to the two reactions. Integration of the resultant distribution functions over the complete Chew-Low plot yields fragmentation cross sections increasing approximately as log s; in addition the observed features of the x, pL and pT2 projections and of the pL-pT correlation are well-described in the fragmentation regions. Central production contributions are isolated by subtracting the calculated fragmentation distributions

A triple-Regge analysis of the inclusive reaction pp → Λ + X++ at 19 GeV/c

Abstract The inclusive reaction pp → Λ + X ++ at 19 GeV/ c beam momentum has been analyzed in terms of the triple-Regge formalism. A good description of the structure function is achieved for events with | t | c ) 2 . The effective trajectory obtained from fits to the M 2 / s distribution in different t bins is α R ( t ) = −(0.38 ± 0.11) + (1.15 ± 0.07) t , which holds up to a | t | value of 4 (GeV/ c ) 2 . This is consistent with the K trajectory rather than the K ∗ trajectory which has been reported from other experiments.

Study of the reaction K+p→ K*0 (890) Δ++ from 4.6-16.0 GeV/c

Abstract A systematic analysis is presented on the reaction K + p → K ∗0 (890) Δ ++ for nine incident momenta between 4.6–16.0 GeV/ c . Cross sections, differential cross sections and vector meson single density matrix elements are given. As a function of energy, little if any change is observed in either the shapes of the differential cross sections or in the values of the density matrix elements. The data are interpreted in terms of current ideas on t -channel exchange mechanisms.

Study of the inclusive reaction K+p → K0 + anthing at 5, 8.2 and 16 GeV/c in the proton fragmentation region

Abstract The inclusive reaction K+p → K0X is studied at 5, 8.2 and 16 GeV/c. The inclusive cross sections as well as the inclusive transverse and longitudinal distributions are given. The energy dependence of the structure function in the proton fragmentation region is found to be consistent with s−1-behaviour indicating the presence of f′ - ϕ exchange in the missing mass channel, with a relative contribution of 50–70%.

Inclusive Δ++ production in K+p interactions at 8.2 and 16 GeV/c

Abstract The reaction K + p→ Δ ++ (1236)+ anything is studied at beam momenta 8.2 and 16 GeV/ c and compared with other Δ ++ producing reactions. We find that the low-mass Δ ++ π − enhancement affects the shapes of Δ ++ inclusive distributions. The triple-Regge formula is found to be consistent with the data. Dual properties of this formula are successfully tested.

Study of the K+π− total cross section for c.m. energy up to 3.4 GeV

Abstract The reaction K + p→Δ ++ (1236) + anything is studied at a beam momentum of 16.0 GeV/ c . The total and topological cross sections for K + π − interactions are estimated by a Chew-Low extrapolation from threshold to the c.m. energy of 3.4 GeV by the maximum likelihood method.

Inclusive K0, K∗+(892) and π± production in K+p interactions at 8.2 and 16 GeV/c and quark models in the central and fragmentation regions

Abstract Results are presented on the production of K0, K∗+(892) and π± in the interaction K+p → K0 + π± + anything at 8.2 and 16 GeV/c. The π± forward and backward d σ d x distributions are of the form exp (−Ax). It is shown that the forward and backward values of A in a quark-quark rest frame change after subtraction of the contributions due to the resonances produced. A comparison is made of d σ d x inclusive cross sections for K0s and K∗+(892) with the predictions of a quark model in the fragmentation region. The experimental cross section matches the theoretical predictions for K0s but disagree with those for K∗+(892).

A comparison of the production of K∗ (890) in K+p and K−p interactions

Abstract Results are presented on an analysis of the reaction K + p → K ∗+ (890) p at 16 GeV/ c and compared with data at lower incident momenta and with corresponding results for the reaction K − p → K ∗− (890) p. It is found for both reactions that the energy dependence of the cross section exhibits a simple ( p − n lab behaviour.

Determination of the K+π- total cross section for c.m. energy up to 1.8 GeV

Abstract The reaction K + p → Δ ++ (1236) + anything is studied at beam momentum 8.2 GeV/ c . The spin density matrix of the Δ ++ shows than one-pion exchange is dominant at low-momentum transfer. The total and topological K + π − cross sections have been determined by a Chew-Low extrapolation in the cm energy range from threshold to 1.8 GeV, using three different methods of extrapolation.