In a sample of 108 563 pictures taken with the Fermilab 30-inch hydrogen bubble chamber, exposed to a 360-GeV/c π− beam, we have observed 19 453 interactions in a selected fiducial region. The observed charged multiplicity distribution has been corrected for the effects of scan efficiency, errors in prong count, missed close-in vees, secondary interactions, and neutron stars and for Dalitz pairs. The two-prong events have been corrected for losses at low −t. The total cross section is measured to be 25.25 ± 0.35 mb, and the elastic cross section is 3.61 ± 0.11 mb with an exponential slope of (8.82 ± 0.30) (GeV/c)−2. The average charged-particle multiplicity for inelastic events is 8.73 ± 0.04, and the second moment f2 is measured to be 9.83 ± 0.23.
SYSTEMATIC CORRECTIONS INCLUDED IN ERRORS.
FROM FIT, FORWARD D(SIG)/DT = 31.84 +- 0.68 MB/GEV**2, AND AGREES WITH OPTICAL POINT FROM MEASURED TOTAL CROSS SECTIONS.
We have studied backward baryon and meson production in π−p→pπ+π−π− at 8.0 GeV/c using a streamer chamber triggered by the detection of a fast forward proton. Our data sample (1227 events) displays prominent N*ρ and N*f quasi-two-body production. These states are investigated with regard to the peripheral nature of the production mechanism and sequential decay of the excited baryon and meson systems. The quasi-two-body production of N*ρ and N*f intermediate states is consistent with u-channel proton exchange as the dominant production mechanism. In the π+π−π− mass distribution we observe a 3- to 4- standard-deviation enhancement at M3π=1897±17 MeV/c2 with full width at half maximum = 110 ± 82 MeV/c2, but find no but find no evidence for backward A1 or A2 production. We observe Δ++(1232) production in the pπ+ effective mass distribution.
THESE VALUES ASSUME ONLY RHO(11) IS NON-ZERO. VALUES FOR OTHER RHO(MM) ARE QUOTED IN PAPER. SIG ERRORS INCLUDE OVER-ALL NORMALIZATION UNCERTAINTY, BUT NO BACKGROUND CORRECTIONS HAVE BEEN MADE.
STATISTICAL ERRORS ONLY, NO BACKGROUND CORRECTION.
STATISTICAL ERRORS ONLY, NO BACKGROUND CORRECTION.
Results are presented on the topological cross sections obtained for antiproton-proton interactions from an exposure of the Fermilab 30-inch bubble chamber to a 100 GeV/ c negative beam enriched in p 's. The p p inelastic cross section is found to be σ inel = 34.6 ± 0.4 mb, and the average inelastic charged particle multiplicity to be 〈 n 〉 = 6.74 ± 0.05.
ERRORS ARE STATISTICAL ONLY EXCEPT FOR 2-PRONG CROSS-SECTIONS.
EXPONENTIAL FIT TO ELASTIC T DISTRIBUTION TO CORRECT FOR AN APPARENT LOSS OF EVENTS AT SMALL -T.
MOMENTS OF 100 GEV/C AP P MULTIPLICITY DISTRIBUTION.
Strong evidence is presented for quasi-two-body production of a π + p enhancement with mass 1881±6MeV and width 219±23MeV, recoiling off vector mesons ϱ O and ω from π + p interactions at 7.1 GeV/ c and K * o (890) from K + p interactions at 12 GeV/ c . The most probable J P assignment for this object is 7/2 + , making it a likely candidate for the Regge recurrence of Δ(1236).
JACKSON FRAME.
JACKSON FRAME.
Using new data from 100 GeV c π − interactions, we find the energy dependence of the invariant cross-section in the target fragmentation (central) region to be consistent with an A + Bs − 1 2 (C + Ds − 1 4 ) behavior. The leading particle peak near x = + 1 exhibits a width in x which becomes smaller with increasing energy and an integrated cross section which is approximately energy independent.
No description provided.
The differential cross section of π+p elastic scattering has been measured in two high-statistics bubble-chamber exposures at laboratory beam momenta of 3.7 and 7.1 GeV/c. A new feature suggested by these data is a dip in dσdu at −u≃3 GeV2. This dip corresponds well to the third zero of J0(b−u′), where ℏcb=1 fm. The effective u-channel Regge trajectory computed for these two energies has a slope of 0.22 ± 0.26.
No description provided.
A search for the production of charmed particles in 15-BeV/c π+p interactions has been carried out. The search was sensitive to charmed particles in the 1.5 to 4.0 BeV mass range, with lifetimes ≲10−11 sec, decaying into a strange particle with up to eight additional pions. No evidence for the production of such particles was found.
No description provided.
Evidence is presented for a new meson resonance at 2340±20 MeV, with a width of 180±60 MeV, decaying primarily into ρρπ. The resonance, which is observed in 15-GeV/c π+p interactions, has isotopic spin 1 or 2 and odd G parity. The cross section for production of the ρρπ state is 7.3±1.7 μb. Branching ratios into ρρπ and other decay modes are given.
No description provided.
We have done a JP analysis of the low-mass π+ω system, using the reaction π+p→π+ωp at 7.1 GeV/c. We find that the B resonance cannot be JP=0− and must belong to the unnatural-parity series (1+, 2−, 3+,...), regardless of the amount of interference between the B and the background. If we assume that the B does not interfere with the background, we find that all JP states for the resonance are rejected except for 1+. Even if interference effects are allowed in the analysis, a good fit with reasonable parameters is obtained only with the 1+ hypothesis for the B meson. In an appendix, we give relevant theoretical formulas appropriate for a πω system with any number of spin-parity states and arbitrary degrees of interference among them.
TAKING INTO ACCOUNT 0- AND 1+ SMOOTH BACKGROUND UNDER THE B MESON. EVENTS WITH 1.08 < M(PI+ OMEGA) < 1.38 GEV.
Studies have been made of the reactions π + p→p π + π + π − and π − p→p π + π − π − , both at an incident pion momentum of 18.5 GeV/ c . The two-body (primarily Δ ++ and ϱ o and three-body (low-mass A enhancement, A 3 , N ∗ (1400), and N ∗ (1700)) subsystems are discussed. Cross sections for all significant channels of the reactions are given.
No description provided.
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