G.T. Jones

Isospin analysis of the reactions π± p → π (N π) at 8 GeV/c and comparison with the results at 16 GeV/c

Abstract An isospin analysis of the reaction π ± p → π (N π ) at 8 GeV/ c has been made and the results are compared with an analogous analysis at 16 GeV/ c previously published, to determine the energy dependence of the effects studied. It is found that isospin-zero-exchange processes are dominant in both cases and practically energy independent, isospin-one-exchange processes are less abundant and are decreasing with increasing energy. Interference effects are, at both energies, very small. The broad enhancement between 1.2 and 1.7 GeV in the I = 1 2 ( N π) mass spectrum due to isospin-zero-exchange, previously reported, is now studied in various mass-bins. It is found that (a) all mass intervals have approximately the same weak energy dependence, (b) all mass intervals have exponential d σ /d t distributions and (c) the slope of these d σ /d t distributions decreases sharply (from ∼12 to ∼3 GeV −2 ) as the mass increases. The results are consistent with the interpretation of this enhancement as predominantly due to diffraction dissociation of the target proton.

Spin parity structure of the Q and L enhancements in K−p → (K−π−π+)p at 10 and 16 GeV/c

Abstract A parital wave analysis of the (Kππ) system produced in K−p → (K−π−π+)p at 10 and 16 GeV/c has been performed. It is found that in 88% of the cases the Kππ) system is in unnatural spin-parity (JP) states 0−, 1+, 2− …, with contributions from many decay modes, κπ, K ∗ (890)π, K ∗ (1420)π, K ϵ, K ϱ and Kf . More than one decay m and JP state are required to describe the Q and L enhancements, suggesting a composite structure of these enhancements. The (Kππ) system is produced dominantly (∼95%) by natural parity exchange. Overall, the production mechanism of the (Kππ) system is remarkably similar to that of the 3π system in π−p → (π−π−π+)p, even i detailed spin-parity structure.

Cross sections for neutrino and antineutrino neutral current interactions

Abstract The cross sections for ν and ν neutral current interactions for which the hadron energy is >15 GeV have been measured. These results, and the ratios of neutral current to charged current cross sections, are in agreement with the Weinberg-Salam model. Values of sin 2 θ W have been obtained both with and without the use of a parameterisation for the hadronic part of the interaction; the values are in good agreement with each other and the preferred result, that obtained by the method independent of hadronic models, is sin 2 θ W = 0.22 ± 0.05.

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.

Approach to scaling in proton fragmentation studied in the reactions K+p → π±X and K−p → π±X

Abstract Data are presented on inclusive single particle distributions in the proton fragmentation region for the reactions K + p → π ± X at 8.2 and 16 GeV/ c and K − p → π ± X at 10 and 16 GeV/ c . The energy dependence is studied and compared with the dual Regge model predictions for approach to scaling. None of the existing models is in full agreement with the data. The model of Chan and his collaborators is consistent with our results under the additional assumption of equality of vector and meson coupling constants in the p π + vertex in the Mueller diagram.

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.

Resonance production in the reactions K−p→pK0π+π−π− and K−p→pK0π+π−π−π0 at 10 GeV/c

Abstract We present an analysis of resonance production in the reactions K − p → p K 0 π + π − π − and K − p → p K 0 π + π − π − π 0 at 10 GeV /c , performed by a maximum likelihood method. In neither process is any significant non resonant background found. The former reaction is dominated by K*−(890), Δ++(1236) and ϱ0 production and the latter by K*−, Δ++ and ω0. In the second reaction there is no evidence for any ϱ0 production. Two-body intermediate states appear to be negligible, but the three-body states K*−ϱ0p and K*−Δ++π− definitely contribute. A detailed analysis has been performed of the simultaneous resonance production in K−p→Δ++K*−π− and the predictions of a Veneziano model calculation for this quasi-three-body final state are found to be in good agreement with the experimental results.

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.

Diffraction dissociation, resonances and deck mechanism in the Kω systems of the reactions K±p→(K±ω)p

A study is presented of the reactions K+p→(K+ω)p at 8.25 and 16 GeV/c and K−p→(K−ω)p at 10 and 16 GeV/c and comparison is made with K+ results at 10 GeV/c and K− at 7.3 GeV/c. The (K+ω) and (K−ω) mass spectra both present a strong enhancement very near threshold, while a second peak at ∼1.7 GeV is evident only with incident K− at the lower energies. The threshold peak has very weak energy dependence and is mostly due to the 1+S state which is produced conserving s-channel helicity. It is suggested that this is another decay mode of the resonance Q1(1290) known to decay mainly into Kϱ. The ratio of the Q1 coupling constants to the Kω and Kϱ decay channels, Rω = gKω2/gKϱ2 is determined to be 0.21±0.04. The enhancement at 1.7 GeV is predominantly, but not exclusively, due to the 2− state. While the K+ and K− induced reactions give basically similar results, small differences are observed that can be qualitatively explained in the framework of the Deck model.

A spin-parity analysis of the K+K+K− system produced in the reaction K+p → K+K+K−p

Abstract We present the first spin-parity analysis of the K + K + K − ) system produced in the reaction K + p → K + K + K − p, and show that the general features of this system resemble those of the (ππ + π − ) and Kπ + π − ) systems produced in the reactions π (K)p → π (K) π + π − p. There is a low mass enhancement, (47 ± 11)% of which corresponds to 1 + states decaying to Ko. At higher (K + K + K − ) masses 2 − → Kf′ becomes increasingly significant and at all masses there is a 0 − contribution of roughly 30%.