A magnetic spectrometer and counter telescope system was used to detect positive pions photoproduced singly in a liquid hydrogen target. Measurements of the differential cross section were made at mean laboratory photon energies, k = 1.1, 1.2, 1.3, and 1.4 GeV and in the angular range from 5° to 165 ° in the center-of-momentum system of the pion. The shape of the angular distribution of the differential cross sections at each value of k is very similar to that of the previously measured distribution at k = 1.0 GeV. The angular distributions were integrated to give the total cross sections. The third pion-nucleon "resonance" peak is seen to be very close to k = 1.0 GeV. A leveling off of the total cross section at k = 1.4 GeV may be due to the fourth "resonance". The accurate small angle data at k = 1.1 and 1.2 GeV permitted a reasonable extrapolation of the differential cross section to the pion-nucleon pole. The value of the pion-nucleon coupling constant, f, was extracted from this extrapolation. The result was f^2 = 0.078 ± 0.011.
No description provided.
No description provided.
No description provided.
An analysis of the reaction K−p→K−pπ+π− at 2.0-GeVc incident momentum is presented. The total cross section for the reaction is 627±20 μb, based on 4519 events. The reaction is dominated by resonance production through several channels which overlap kinematically but do not appear to interferesubstantially. A maximum-likelihood procedure was used to determine the production fractions, which for the major channels are 0.44±0.02 for N*++(1236), 0.145±0.02 for Y*0(1520), 0.10±0.03 for N*+(1688), and 0.20±0.02 for simultaneous K¯*0N*0. Evidence is presented for the production of Y*+(1765) and its decay into Y*0(1520) as well as for production of Y*+(1660) with decay into K−pπ+. A four-standard-deviation enhancement is present at a K−π+ invariant mass of 690 MeV. Angular correlation data are presented for the N*++K−π−, Y*0π+π−, and K¯*0N*0 reaction channels. However, the difficulty of separating the various channels prevents a detailed study of the reaction dynamics.
No description provided.
We report measurements of the photoproduction from hydrogen of single π+ mesons at gamma-ray energies of 3.4 and 5.0 BeV and at laboratory angles of 5.1°, 7.1°, 9.9°, and 15.1°. The s dependence at fixed t is derived for momentum transfers of -0.20, -0.37, and -0.70 BeV2. The pion data are compared with a Reggeized one-pion-exchange model.
No description provided.
Total cross sections of K+ and K− mesons on protons and deuterons have been measured in a transmission experiment over the range of laboratory momentum 0.6-2.65 GeV/c. Measurements have been made on K− at 58 momenta at intervals of 25-50 MeV/c; the experimental accuracy is better than 1% above 700 MeV/c, and the momentum resolution of the beam is ±0.6%. Structure is observed in the total cross sections suggesting or confirming Y1∗ resonances at masses of 1665, 1768, 1905, 2020, 2250, and 2455 MeV/c2 and Y0∗ resonances at masses of 1695, 1819, 1870, 2100, and 2340 MeV/c2. The K+ measurements are less extensive, and are concentrated in the momentum range below 1.5 GeV/c; the experimental errors are typically ±0.2 mb. Structure previously reported in the K+p and K+d total cross sections near a laboratory momentum of 1.2 GeV/c is confirmed. Total cross sections of K+ and K− on carbon have been measured at a number of momenta with an accuracy of about ±2%.
No description provided.
No description provided.
Total cross sections of π+ and π− mesons on protons and deuterons have been measured in a transmission experiment to relative accuracies of ±0.2% over the laboratory momentum range 0.46-2.67 GeV/c. The systematic error is estimated to be about ±0.5% over most of the range, increasing to about ±2% near both ends. Data have been obtained at momentum intervals of 25-50 MeV/c with a momentum resolution of ±0.6%. No new structure is observed in the π±p total cross sections, but results differ in several details from previous experiments. From 1-2 GeV/c, where systematic erros are the smallest, the total cross section of π− mesons on deuterons is found to be consistently higher than that of π+ mesons by (1.3±0.3)%; about half of this difference may be understood in terms of Coulomb-barrier effects. The πd and πN total cross sections are used to check the validity of the Glauber theory. Substantial disagreements (up to 2 mb) are observed, and the conclusion is drawn that the Glauber theory is inadequate in this momentum range.
No description provided.
No description provided.
Photoproduction of resonances has been studied using positron annihilation radiation at 5.25 GeV in the SLAC 40-inch hydrogen bubble chamber. Results are presented on the nonstrange particle events and related to the vector dominance model.
No description provided.
We present the results of a study of 1173 uniquely identified events of the K 0 π + p final state produced in 10 GeV/ c K + p interactions. This final state is dominated by the quasi two-body processes K + p → K 0 N ∗+ (890 p and K + p → K ∗+ (1420) p . The background is very low and there is little overlapping of resonance bands. We present cross sections, t -distributions and decay angular distributions for the contributing reaction channels. Dips are observed near t = 0 in the differential cross sections for all three processes.
BREIT-WIGNER FIT.
NUMERICAL VALUES TAKEN FROM THE COMPILATION LST7V2 FOX 72B.
No description provided.
Production of B(1235) and ρ(1710) mesons is observed in the four-pion decay modes π+π+π−π0 in 16−GeVc π±p collisions. Decay distributions and branching fractions into various modes are presented. Absence of the two-pion mode π−π0 for the ρ(1710) is noted.
No description provided.
Data from the reactions π−p→π−π−π+p and π+p→π+π+π−p have been obtained at 16 GeV/c in approximately equal samples from the BNL 80-in. hydrogen bubble chamber. We have studied both reactions for resonance production and compared our results with predictions of the one-pion-exchange model (OPEM) calculated by Wolf. The four-body longitudinal phase-space (LPS) plot suggested by Van Hove was used to analyze the data from both reactions. The events were separated according to distinct regions of the LPS plot in order to study the following classes of quasi-two-body final states: (1) diffractively produced three-pion states, (2) diffractively produced ππp states, (3) double-resonance production such as ρ0Δ++, (4) single-resonance production such as π−π−Δ++. The Van Hove analysis provided a much cleaner separation of resonances from background effects than the usual techniques. We observe production of the A1 and A2 mesons as well as the N*(1470) and N*(1700) isobars in the π+π−p system for both reactions. There is strong formation of the doubly resonant states ρ0Δ++ and f0Δ++ and the general features of the nondiffractive events are all in good agreement with one-pion exchange. Detailed comparisons between the data and the OPEM in each LPS plot region show that Van Hove analysis provides a sensitive test for the OPE model.
DEDUCED FROM PRONG CROSS SECTIONS NORMALIZED USING THE DATA OF K. J. FOLEY ET AL., PRL 19, 330 (1967).
No description provided.
No description provided.
Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel γp→pπ+π−. A model-independent analysis of the ρ0-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction γp→pρ0 proceeds almost completely through natural parity exchange for squared momentum transfers |t|<1 GeV2 and that the ρ production mechanism is consistent with s-channel c.m. helicity conservation for |t|<0.4 GeV2. A cross section for the production of π+π− pairs in the s-channel c.m. helicity-conserving p-wave state is determined. The ρ mass shape is studied as a function of momentum transfer and is found to be inconsistent with a t-independent Ross-Stodolsky factor. Using a t-dependent parametrization of the ρ0 mass shape we derive a phenomenological ρ0 cross section. We compare our phenomenological ρ0 cross section with other experiments and find good agreement for 0.05<|t|<1 GeV2. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for ρ0 photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a ρ0 cross section. We determine cross sections and nine density-matrix elements for γp→Δ++π−. The parity asymmetry for Δ++ production is incompatible with simple one-pion exchange. We compare Δ++ production with models.
FROM QUOTED TOPOLOGICAL CROSS SECTIONS. 1.44 GEV CROSS SECTION PUBLISHED PREVIOUSLY.
No description provided.
NO TMIN CORRECTION HAS BEEN MADE.
Forum