None
Cross sections based on total PI+ P cross section =25.8 mb (Vondardel, PRL 8, 173 (1962)).
An extensive investigation of antiproton-proton interactions at 5.7 GeV/c without strange-particle production was carried out using a hydrogen bubble chamber. Cross-sections for different channels are given and discussed. The reliability of the analysis was checked using artificially generated events. The cross-sections for elastic scattering, for all processes involving annihilation, and for all other inelastic processes are respectively σel=(16.3±0.6)mb,σannlbil=(22.5±2.0)mb, σinel=(24.8±2.0)mb. TheN * 1:38 is present both in the single and multiple pion production channels. For the reaction MediaObjects/11539_2007_Article_BF02720569_f1.jpg a cross-section of (1.05±0.21) mb was obtained. Cross-sections forN * 1238 production in other channels are also given. Some indication of the presence ofI=1/2 isobars was found in the nucleon-pion and the nucleon-two-pion systems. The inelastic nonannihilation reactions were found to be strongly peripheral. The one-pion exchange model including either a form factor or corrections for absorption was applied to the reaction MediaObjects/11539_2007_Article_BF02720569_f2.jpg . Neither version of the model could correctly account for all features of the reaction. The average number of pions in the annihilation was found to be 7.3±0.6. The presence of an asymmetry in the angular distribution of the charged pions was confirmed at this energy; it is due mostly to high-energy pions. The production of ρ and ω mesons was observed in various annihilation channels. Rates of up to 80% for ρ production and up to 15% for ω production were obtained by fitting phase-space and Breit-Wigner curves to the effective-mass distributions of different channels.
No description provided.
'1'.
'1'.
We report a study of 20 exclusive reactions measured at the AGS at 5.9 GeV/c incident momentum, 90° center of mass. This experiment confirms the strong quark flow dependence of two-body hadron-hadron scattering at large angle. At 9.9 GeV/c an upper limit had been set for the ratio of cross sections for (p¯p→p¯p)(pp→pp) at 90° c.m., with the ratio less than 4%. The present experiment was performed at lower energy to gain sensitivity, but was still within the fixed angle scaling region. A ratio R(p¯ppp)≈140 was measured at 5.9 GeV/c, 90° c.m. in comparison to a ratio near 1.7 for small angle scattering. In addition, many other reactions were measured, often for the first time at 90° c.m. in the scaling region, using beams of π±, K±, p, and p¯ on a hydrogen target. There are similar large differences in cross sections for other reactions: R(K−p→π+Σ−K−p→π−Σ+)≈112, for example. The relative magnitudes of the different cross sections are consistent with the dominance of quark interchange in these 90° reactions, and indicate that pure gluon exchange and quark-antiquark annihilation diagrams are much less important. The angular dependence of several elastic cross sections and the energy dependence at a fixed angle of many of the reactions are also presented.
Cross sections at 90 degrees in the centre-of-mass.
No description provided.
No description provided.
Data of the ηπ − system were obtained in the reaction π − p → ηπ − p at 6.3 GeV/ c beam momentum. About 17 k events of ηπ − were collected in the mass range 0.8 ⩽ M ηπ - ⩽ 1.8 GeV/ c 2 and in the range of the momentum transfer squared 0.075 ⩽ | t ′| ⩽ 0.60 (GeV/ c ) 2 . A large forward-backward asymmetry was observed around 1.3 GeV/ c 2 in the Gottfried-Jackson frame of the ηπ − system. A partial wave analysis of the data was performed. A peak of the D + wave attributed to a 2 (1320) is clearly seen. An enhancement is observed around 1.3 GeV/ c 2 in the P + wave.
No description provided.
No description provided.
No description provided.
No description provided.
No description provided.
We present preliminary results on the measurement of a variety of exclusive hadron interactions at center of mass scattering angles of 90°. Data are also presented which show the relative transparency of nuclei to πp and pp elastic scattering in this kinematic range.
No description provided.
No description provided.
No description provided.
An experimental study was made of a ωπ 0 system produced in the charge exchange reaction π − p→ ωπ 0 n at 8.95 GeV/ c . The moment analysis was performed to study the spin-parity of the system in the mass region between 1.04 and 1.88 GeV. A clear peak of b 1 (1235) was observed in the J PC = 1 +− wave. No significant structure was seen in the 1 −− wave. An upper limit is obtained to be at most 1.9 μb for σ ( π − p→X 0 n)Br(X 0 → ωπ 0 ) for X 0 with a width of 130 MeV at 1480 MeV, where C(1480) meson with J PC = 1 −− has been reported in a φπ 0 decay mode.
Upper limit for pi- p --> X0 n (X0 --> omega pi0) with width 130 MeV at 1480 MeV where the C(1480) has been reported with JPC = 1-- in the phi pi0 decay mode.
A high-statistics experiment on the reaction π − p→ π + π − π 0 n at 8.06 GeV/ c has been performed using a spectrometer detecting both charged particles and gamma rays. A partial-wave analysis based on the isobar model has been carried out for π + π − π 0 data in the mass range between 0.86 and 1.50 GeV for four t ′ regions: 0.0–0.1, 0.1–0.25, 0.25–0.45 and 0.45–0.95 (GeV/ c 2 ). Two axial-vector resonances, a 1 (1260) and h 1 (1170), were observed in the analysis. The masses and widths of a 1 and h 1 were determined to be M (a 1 = 1121 ± 8 MeV, Λ (a 1 = 239± 11 MeV, M (h 1 = 1168±4 MeV and Λ (h 1 = 345±6 MeV, respectively, by fitting the Breit-Wigner formula to the partial wave amplitude. A fit including the Deck type background was also tried in each t ′ region. The results showed a small effect on these resonance parameters and were consistent with those obtained by the simple Breit-Wigner fitting.
Production cross section of A2(1320) from the 12+ rhoD1+ partial wave.
Production cross section of H1(1190) from the 01+ rhoS0+ partial wave.
Production cross section of A1(1270) from the 11+ rhoS1+ partial wave.
High statistics data of the ηππ system in π − p → ηπ + π − n were obtained. A partial wave analysis was performed in the mass region between 1.37 and 1.85 GeV. Resonant structures were observed in the IJ PC = 11 −− wave around 1.6 GeV and in 13 −− around 1.7 GeV. The structure in 11 −− was fitted with a single Breit-Wigner and also fitted with two Breit-Wigner's. The result suggests the possible existence of two vector resonances around 1.6 GeV. The structure in 13 −− is considered to be the π 3 (1690).
Result of single Breit Wigner fit around 1.6 GeV. Called here $M(1635).
Results of double Breit Wigner fit around 1.6 GeV. $M(1446) and $M(1701).
Result of Breit Wigner fit around 1.7 GeV.
Cross sections or upper limits are reported for 12 meson-baryon and two baryon-baryon reactions for an incident momentum of 9.9 GeV/c, near 90° c.m.: π±p→pπ±,pp±,π+°±,K+Σ±, (Λ0/Σ0)K0; K±p→pK±; p±p→pp. By studying the flavor dependence of the different reactions, we have been able to isolate the quark-interchange mechanism as dominant over gluon exchange and quark-antiquark annihilation.
No description provided.
No description provided.
Forum