We present measurements on the inclusive structure function for π 0 photoproduction for the incident photon energy range of 2.8–4.8 GeV. Comparisons are made with electroproduction data and it is found that the scaling behaviour already observed for finite q 2 continues to be valid at q 2 = 0.
No description provided.
We have studied backward meson and baryon production in π−p→nπ+π− at 8 GeV/c using a streamer chamber triggered by the detection of the interaction of the neutron in thick-plate optical spark chambers. Our data sample of 866 events is dominated by the quasi-two-body final states Δ−(1232)π+, nρ0, and nf0. We study the differential and total backward cross sections for these states and the decay angular distributions of the resonances. The results for the Δ− and ρ0 indicate that both nucleon and Δ exchange in the u channel are important in their production, while f0 production is, as expected, consistent with nucleon exchange.
No description provided.
BACKWARD DIP.
No description provided.
We present experimental evidence for a resonant behaviour of the hadron production from e + e − annihilations at the e + e − storage ring ADONE. A Breit-Wigner fit to the enhancement present between 1800 and 1850 MeV gives the following parameters M = 1812 −13 +7 MeV, Γ = 34 −15 +21 MeV.
MULTIHADRON EVENTS (AT LEAST THREE CHARGED TRACKS) PER UNIT LUMINOSITY.
Measurements have been made of the target asymmetry parameter for photoproduction of π 0 mesons from protons, using a butanol polarised target with a 3 He cryostat. Results were obtained at 14 incident photon energies between 0.7 GeV and 1.45 GeV over an angular range ∼40° to 145° c.m. The recent analysis of Barbour and Crawford provides a very good fit to the data.
No description provided.
No description provided.
No description provided.
A measurement of backward photoproduction of charged pion pairs on protons is reported. The pion pair mass spectrum shows strong ϱ ° and f production. Data are presented on the u and s dependence for ϱ O and f, together with the decay polarisation for the ϱ O .
No description provided.
No description provided.
AVERAGED OVER U RANGE OF EXPERIMENT. NO EVIDENCE FOR ANY LARGE S-WAVE CONTRIBUTION TO THE PI PI SYSTEM IN THE RHO0 MASS REGION (RHO(0S) < -0.03 +- 0.13). U CHANNEL FRAME: Z AXIS IN INCIDENT PROTON DIRECTION IN THE DIPION REST FRAME.
In a search for optical rotation near the 8755-Å magnetic-dipole absorption line in atomic Bi, our first results set an upper limit F<10−6 on a parity nonconserving amplitude associated with the line. This limit improves upon earlier parity tests in atoms by three orders of magnitude. Further improvement of at least another order of magnitude appears possible by this method which should then provide an exacting test of parity conservation in the neutral weak-current interaction in atoms.
No description provided.
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.
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.
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.
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.
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