Angular distributions are presented for p¯−p elastic scattering at 8 and 16 GeV/c for |t|<1.3 (GeV/c)2. At both energies there is structure in the differential cross sections in the region 0.5<~|t|<~1.0 (GeV/c)2, similar to that observed at lower energies. The diffraction peak continues to expand with increasing incident momentum.
No description provided.
No description provided.
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Elastic scattering of p¯ on p has been studied for cosθc.m. between -0.88 and -1.0 and Plab(p¯) between 0.70 and 2.16 GeV/c. The momentum dependence of the cross section shows a sharp dip at 0.9 GeV/c and a broad peaking around 1.4 GeV/c. The possibility of the peak resulting from direct formation of boson resonances has been studied. Alternatively, a diffraction model agrees qualitatively with our data and other elastic data at different angles.
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No description provided.
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Neutron-proton total cross-sections were measured in the momentum range from 8 GeV/ c to 21 GeV/ c with an accuracy of better than 2% using a 0 o neutron beam at the CERN Proton Synchrotron. The np total cross-section drops from 39.7 mb at 8 GeV/ c at 21 GeV/ c , and thus follows closely the pp total cross-sections in this momentum interval.
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Differential cross sections have been measured for nucleon-isobar production and elastic scattering in p−p interactions from 6.2 to 29.7 GeVc in the laboratory angle range 8<θsc<265 mrad. N*' s at 1236, 1410, 1500, 1690, and 2190 MeV were observed. Computer fits to the mass spectra under varying assumptions of resonance and background shapes show that conclusions on t and s dependence are only slightly affected despite typical variations in absolute normalization of ± 35%. Logarithmic t slopes in the small- |t| range are ∼15 (GeVc)−2 for the N*(1410), ∼5 (GeVc)−2 for the N*'s at 1500, 1690, and 2190 MeV, and ∼9 (GeVc)−2 for elastic scattering. Also for the small- |t| data, cross sections for N*'s at 1410, 1500, 1690, and 2190 MeV and for elastic scattering vary only slightly with Pinc consistent with the dominance of Pomeranchuk exchange and with diffraction dissociation. A fit of N*(1690) total cross sections to the form σ∝P−n gives n=0.34±0.06, while for elastic scattering n=0.20±0.05. For the N*(1690) the effective Regge trajectory has the slope αeff′(0)=0.38±0.17. When compared with N* production in π−, K−, and p¯ beams these data also agree with approximate factorization of the Pomeranchuk trajectory. N*(1236) cross sections are consistent with other measurements at similar momenta. For −t>1 (GeVc)−2, elastic scattering cross sections decrease approximately as Pinc−2, and they and N*(1500)− and N*(1690)− production cross sections have t slopes consistent with 1.6 (GeVc)−2.
No description provided.
No description provided.
No description provided.
The K ∗− spectrum in the reaction K − +p → K ∗− +p has been measured at beam momenta 10.9, 13.4 and 15.9 GeV/ c using the missing mass technique. Production of the L(1770), and a Q-K ∗ (1420) enhancement are observed. Differential cross sections in the range of momentum transfer 0.12 < | t pp | < 0.40 (GeV/ c ) 2 are given. The L meson is observed with a width Γ = 100 ± 26 MeV. The mass spectrum between the L and 2.5 GeV does not show significant structure.
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A new method, using spark chambers, for the study of the reactions π ± + p → ϱ ± + p is described. The charged pion and both γ rays from the π ± decay are detected. Differential and integrated cross sections σ π + =50 ± 9 μ b, σ π − =47 ± 9 μ b) for 0.0 ⩽| t |⩽1. (GeV/ c ) 2 and a laboratory momentum ( p Lab ) of 15 GeV/c are presented. The momentum dependence of σ γ ± is well fitted from 2.7 to 16 GeV/c by σ = K p Lab − with n γ + = 1.80 ± 0.80 and n γ − = 1.87 ± 0.15.
Axis error includes +- 17/17 contribution.
Axis error includes +- 17/17 contribution.
Invariant single-particle cross sections for pion and proton production in π ± p interactions at 8 and 16 GeV/ c are presented in terms of integrated distributions as functions of x , reduced rapidity ζ and p ⊥ 2 , and also in terms of double differential cross sections E d 2 σ /(d x d p ⊥ 2 ) and d ζ d p ⊥ 2 ). A comparison of π ± and π − induced reactions is made and the energy dependence is discussed. It is shown that the single-particle structure function cannot be factorized in its dependece on transverse and longitudinal momentum. For the beam-unlike pion, there is an indication for factorizability in terms of rapidity and transverse momentum in a small central region.
No description provided.
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A systematic analysis is presented on the reaction K + p → K ∗0 (890) Δ ++ for nine incident momenta between 4.6–16.0 GeV/ c . Cross sections, differential cross sections and vector meson single density matrix elements are given. As a function of energy, little if any change is observed in either the shapes of the differential cross sections or in the values of the density matrix elements. The data are interpreted in terms of current ideas on t -channel exchange mechanisms.
No description provided.
No description provided.
No description provided.
A partial-wave analysis of the (K ππ ) 0 system produced in the charge exchange reaction K − p →( K 0 π + π − ) n has been made in the mass range 1.04 ⩽ M (K ππ ) < 1.56 GeV c data at 8, 10 and 16 GeV/ c . It was found that in about 2 3 of the cases, the (K ππ ) 0 system is produced in states of unnatural spin-parity, namely J P = 0 − and 1 + ; the rest is in the natural spin-parity state J P = 2 + state is consistent with being all K ∗ (1420). The unnatural spin-parity states are produced mostly (∼ 80% of the events) by natural parity exchange. The facts that unnatural spin-parity states are produced in this non-diffractive channel, with J P = 1 + dominant, and that the exchange responsible for their production is mostly of natural parity, are similar to what was found for the charged (K ππ ) − system in the diffractive reaction K − p→(K ππ ) − p. However, the absolute value and the energy dependence of the cross sections are very different in the two cases.
CORRECTED FOR UNSEEN AK0 DECAY MODES.
ACTUALLY CROSS SECTIONS FOR PRODUCTION IN MASS REGION 1.04 < M(AK0 PI+ PI-) < 1.56 GEV IN THE STATES JP = 1+, 2+ AND 0- RESPECTIVELY.
The average charged particle multiplicity, 〈 n ch ( M X 2 )〉, in the reaction K + p→K o X ++ is studied as a function of the mass squared, M X 2 , of the recoil system X and also as a function of the K o transverse momentum, p T , at incident momenta of 5.0, 8.2 and 16.0 GeV/ c . The complete data samples yield distributions which are not independent of c.m. energy squared, s , They exhibit a linear dependence on log ( M X 2 X / M o 2 )[ M o 2 =1 GeV 2 ] with a change in slope occurring for M X 2 ≈ s /2, and do not agree with the corresponding distributions of 〈 n ch 〉 as a function of s for K + p inelastic scattering. Sub-samples of the data for which K o production via beam fragmentation, central production and target fragmentation are expected to be the dominant mechanisms show that, within error, the distribution of 〈 n ch ( M X 2 )〉 versus M X 2 is independent of incident momentum for each sub-sample separately. In particular in the beam fragmentation region the 〈 n ch ( M X 2 )〉 versus M X 2 distribution agrees rather well with that of 〈 n ch 〉 versus s for inelastic K + p interactions. The latter result agrees with recent results on the reactions pp → pX and π − p → pX in the NAL energy range. Evidence is presented for the presence of different production mechanisms in these separate regions.
Two parametrizations are used for fitting of the mean multiplicity of the charged particles : MULT = CONST(C=A) + CONST(C=B)*LOG(M(P=4 5)**2/GEV**2) and MULT = CONST(C=ALPHA)**(M(P=4 5)**2/GEV**2)**POWER.
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