K. E. Johansson

Inclusive particle production in 400 GeV/c pp-interactions

AbstractWe report on a study of inclusive particle production in pp-interactions at 400 GeV/c. The data are based on 472 K reconstructed events recorded in the NA 27 experiment using the LEBC-EHS facility at CERN. The production cross sections are determined of pseudo scalar (π±,0, η andK±), scalar (f0(975)), vector (ρ±,0(770), ω(783), ϕ(1020),K*0(892), and

Antiproton-proton annihilation into π+π− and K+K− at 6.2 GeV/c

\bar K^{ * 0}

Inclusive production ofρ0 andf2 mesons in π−p interactions at 360 GeV/c

(892)), and tensorf0 mesons, of protons and antiprotons, and theΔ++,+,0(1232), and Λ(1520) baryon resonances in the forward hemisphere of the center of mass system, as well as longitudinal and transverse momentum distributions. The results are compared with predictions of the FRITIOF model and with other experimental data.

Longitudinal Distribution of π±, K±, Protons and Antiprotons Produced in 360 GeV/c π-p Interactions

Abstract Angular distributions of π+ and K+p elastic scattering have been measured for an incident beam momentum of 10.0 GeV/c. For π+p elastic scattering almost the complete angular distribution was measured. The angular distribution of proton-proton elastic scattering was measured for an incident momentum of 9.0 GeV/c in the interval of the four-momentum transfer squared from 0.7 (GeV/c)2 to 5.0 (GeV/v)2. For π+p elastic scattering the structures at −t = 2.8 (GeV/c)2 and −t = 4.8 (GeV/c)2 are less pronounced than at lower momenta. The cross section for scattering at 90° in the c.m. system is of the order of 1 nb/GeV/c)2. For K+p elastic scattering is a break in the angular distribution around −t = 3 (GeV/c)2. The differential cross sections for proton-proton elastic scattering decrease smoothly with increasing momentum transfers.

Search for the Higgs boson in the H -g WW -g lvjj decay channel at root s=7 TeV with the ATLAS detector

The angular distributions for the two annihilation channels pp→π+π− and pp→ K+K− have been measured at 6.2 GeV/c. The two-pion channel shows peripheral peaks for π+ and π− going forward, and the two-kaon channel shows a peripheral peak for the K− going forward. The results have been compared with the line-reversed elastic backward scattering reactions and also with a constituent interchange model.

Search for Anomaly in Low-Energy Positron - Thorium Scattering

Bose-Einstein correlations among identically charged pions produced inpp collisions at 400 GeV/c are studied using the EHS spectrometer. Empoying the Kopylov-Podgoretskii parametrization, the average size of the emitting regionrk and its lifetime τ for pion production were determined to berk=1.71±0.04 fm andcτ=0.89±0.05fm. The average sizerg in terms of the Lorentz invariant Goldhaber parametrization was determined to berg=1.20±0.03fm. A decrease of the size with increasing momentum of the pions was observed. The size and the incoherence parameter of the pion emitting region were determined as a function of the charged particle multiplicity and the momentum of the pions. Identified charged kaons were used to study Bose-Einstein correlations among identically charged kaonsK±K±. The average size of the emitting region for kaon production was determined to berk=1.87±0.33fm in terms of the Kopylov-Podgoretskii parametrization. A study of the influence of a reference sample is presented.

Determination of large-angle cross-sections for π-+p → π-+Δ+ at 5 GeV/c

We report on a study ofρ0 andf2 inclusive production in π−−p interactions at 360 GeV/c, using the LEBC-EHS set-up at CERN and reconstructing about 165000 events. Theρ0,f2 andρ30 cross sections are determined forxF>0,xF>0.4 andxF>0.6 respectively and theρ0 andf2 Feynman-x distributions and transverse momentum distributions are presented.

Anti-Proton-Proton Elastic Scattering at 6.2-GeV/c

Results on the longitudinal-momentum distributions of π±, K±, protons and antiprotons produced in 360 GeV/c π− interactions are presented. They are compared with other available data and discussed in terms of π− fragmentation.