Cross sections for π − p→n π o at 5.9, 10.1 and 13.8 GeV/ c incident momentum are presented in the angular region from 180 o to u , the crossed four-momentum transfer squared, of −2(GeV) 2 and the energy dependence is discussed. The cross section for π − p→n η o integrated over the same angular region at 5.9 GeV/ c is also presented.
No description provided.
No description provided.
No description provided.
Results are presented on effective-mass distributions, differentisl cross sections and longitudinal c.m. momentum distributions for the channels K − p → K − p π o , K o p π − and K − π + n , obtained from a sample of approximately 28 000 inelastic two-pronged interactions at 4.2 GeV/ c incident momentum. The results are in satisfactory agreement with the prediction of a generalized Veneziano-model corrected for (non-dual) π -and pomeron exchange. For the channel K − pπ o pomeron exchange contributes about 20% of the cross section. In the channel K − π + n the dual, pion and pomeron contributions are responsible for resp. 15%, 65% and 20% of the total cross section.
BREIT-WIGNER FITS.
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MEASURED OFF GRAPH.
A bubble-chamber study is presented of a 10 events/μb experiment using K − mesons of 4.25 GeV/ c incident momentum. Differential and total cross sections are determined for 7 different reactions: K − p → K 0 n ( la ), → π 0 Λ ( lb ), → ηΛ ( lc ), → η′Λ ( ld ), → π − Σ ( le ), → π + Σ − ( lf ), K + Ξ − ( lg ) . The experimental characteristics in d σ /d t of each reaction are described: (la) shows a levelling off at t = 0 (GeV/ c ) 2 , a break at t = −0.6 (GeV/ c ) 2 and no backward events, (lb) d σ /d t has a smooth behaviour and a measurable backward component with an indication of a dip at u = −0.2 (GeV/ c ) 2 , (1c) d σ /d t shows a dip in the region between t ≈ −0.2 and −0.4 (GeV/ c ) 2 , (ld) d σ /d t has a smooth behaviour; neither this reaction nor the preceding one shows a clear evidence for backward events, (le) d σ /d t has a break at t = −0.5 (GeV/ c ) 2 ; there is a significant cross section in the backward region; (lf) and (lg) show mainly backward production. The polarization of the hyperon is measured in the reactions (lb), (lc), (ld) and (le) in the forward production peak. The statistics do not allow the detection of a definite structure in the polarization but the sign and magnitude are determined. An interpretation of the results is given in terms of a dual Regge model, including the effects of absorption as elaborated recently by several authors.
No description provided.
No description provided.
No description provided.
We have measured ρ0, ω (combined) and ϕ electroproduction over a range of virtual-photon four-momentum Q2 from 0.4 to 2.2 GeV2 and for photon energies ν from 2.7 to 8.6 GeV. We find that the slope of the t (momentum transfer) dependence of the ρ0 and ω forward peak decreases with increasing Q2 to less than half of the photoproduction slope.
The cross section for virtual photon are derived from E- P cross section bydividing on the virtual-photon flux factor.
We have measured ep, eπ+, and eπ− coincidences for scattered electrons in the range Q2=0.4 to 2.2 GeV2 and W=2 to 4 GeV. We find (a) that vector-meson production decreases with Q2 more rapidly than does the total virtual-photon-plus-proton cross section, more rapidly even than the prediction of simple vector dominance, (b) that the slope of the t distribution in ρ and ω production becomes flatter with increasing Q2 and seems to be at least approximately a function of the single variable xρ=(Q2+mρ2)2Mν, (c) that the fraction of final states containing a proton decreases with increasing Q2, (d) that in the central region of longitudinal momenta the inclusive π+ yield seems to increase relative to the π− yield as Q2 increases, and (e) that the average transverse momentum of π− is greater than of π+ in the central region of longitudinal momenta.
No description provided.
The data with (C=Q=RHO+OMEGA) are obtained by excluding the contribution from RHO and OMEGA production.
No description provided.
Results are reported of a study of the hypercharge reactions K − p → ωΛ (la), K − p → φΛ (lb), K − p → φ ∑ o (lc), K − p → ϱ o Λ (ld), K − p → ϱ o ∑ o (le), K − p → ϱ − ∑ + (lf) in a 12 events/ub bubble chamber experiment using K − mesons of 4.25 GeV/ c momentum. Total and differential cross sections are presented as well as the density matrix elements of the peripherally produced vector meson and (except for reaction (1f)) the hyperon polarization. For reactions (1a) and (1b) an amplitude analysis is performed. The mass and the width of the ϱ−, φ− and f-meson have been determined.
FURTHER DATA FROM THIS COLLABORATION ON THESE REACTIONS WITH TEN TIMES BETTER STATISTICS ARE PRESENTED IN M. J. LOSTY ET AL., NP B133, 38 (1978).
No description provided.
No description provided.
Differential cross sections for K−p→K¯0n and K+n→K0p have been measured at 3, 4, and 6 GeV/c using a data sample of 6000 events. Contrary to simple exchange-degenerate models, the ratio of K+ to K− cross sections was found to be approximately 1.35, with little dependence on either s or t. Both reactions show a shallow dip near the forward direction, suggesting the importance of spin-flip amplitudes.
No description provided.
No description provided.
LARGE -T CONTRIBUTIONS (TYPICALLY 12 PCT) ESTIMATED FROM BUBBLE-CHAMBER DATA.
Elastic neutron-proton differential cross sections have been measured between 58 and 391 MeV incident neutron energy at angles in the center-of-mass system from 11° to 54°. Neutrons were scattered from a liquid-H2 target and detected in liquid scintillators. The incident energy of each detected neutron was determined from its time of flight. The data were normalized by placing the detector in the beam. The results are generally consistent with previous data and with the predictions of phase-shift analysis but are of improved accuracy.
No description provided.
No description provided.
No description provided.
We present differential cross sections and the Σ + polarization for the reactions K − p → π ∓ Σ ± using data from a high statistics bubble chamber experiment at 4.2 GeV/ c incident momentum. The statistical level allows a detailed analysis of these reactions over the whole t range. Several significant structures are observed. Comparisons are made with SU(3)-related reactions; for backward production of π − Σ + such a comparison shows good evidence for Δ exchange. The exotic forward peak in K − p → π + Σ − is definitely confirmed.
Axis error includes +- 5/5 contribution.
Axis error includes +- 5/5 contribution.
Axis error includes +- 5/5 contribution.
A sample of 1200 ϕ mesons produced in the Zweig-rule-forbidden reactions π±N→ϕN shows a flat t distribution (slope=1.7 ± 0.2 GeV−2) and a cross section suppressed by 0.0032±0.0004 relative to π−p→ωn. Natural-parity-exchange ω and ϕ production have similar t dependences, while ω and ϕ production by unnatural-parity exchange differ markedly. Interference between the ϕ and the underlying K¯K S wave indicates substantial nucleon-spin incoherence between the amplitudes for ϕ and S-wave production.
Axis error includes +- 10/10 contribution (RES-DEF(RES=PHI,BACK=CORRECTED)).
Axis error includes +- 10/10 contribution (RES-DEF(RES=PHI,BACK=CORRECTED)).
STATISTICAL ERRORS ONLY.
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