The differential cross sections for elastic π − p, K − p , p p and π + p, pp scattering at 39 and 44.5 GeV/ c , respectively, have been measured in the interval of momentum transfer squared 0.15 ≤ ovbt | ≤ 2 (GeV/ c ) 2 .
No description provided.
No description provided.
No description provided.
The reaction γp→ρfast0pπ+π− has been studied with the linearly polarized 20-GeV monochromatic photon beam at the SLAC Hybrid Facility to test the prediction of s-channel helicity conservation in inelastic diffraction for t’<0.4 (GeV/c)2. In a sample of 1934 events from this reaction, the ρ0 decay-angular distributions and spin-density-matrix elements are consistent with s-channel helicity conservation, the π+π− mass shape displays the same skewing as seen in the reaction γp→pπ+π−, and the pπ+π− mass distribution compares well and scales according to the vector dominance model with that produced in π±p→πfast±pπ+π−.
No description provided.
We present experimental results on a number of K − p reactions at 14.3 GeV/ c that have three bodies in the final state. The final states are K − ω p , K − π p , Λπ + π − , Λ K + K − , Λp p , K ∗ − ω p , Λ(1520) K + K − and Λ(1520) p p . Whenever, with one exception explained by the Zweig rule, there is a K − or a proton in the final state, there is a diffractive-like threshold enhancement in the mass spectrum of the two recoiling particles. These enhancements account for a large fraction of the events in all but the Λπ + π − final state, where they cannot occur, and which is dominated by resonance production. We find evidence for the Q 1 (1300) decaying into K − ω .
THE DIFFRACTION DISSOCIATION CROSS SECTIONS ARE FOR DIFFRACTIVE THRESHOLD ENHANCEMENTS IN THE TWO-BODY MASS SPECTRA (WITHIN 500 MEV CM ENERGY OF THRESHOLD).
A partial-wave analysis has been performed of the diffractively produced low-mass ( K ̄ 0 π − π 0 ) system in the reaction K − p → ( K ̄ 0 π − π 0 ) p at 10 and 16 GeV/ c . Thus information complementary to that derived from the K − p → (K − π + π − )p) channel is obtained. The presence of the K ϱ decay mode, besides the dominant K ∗ (890)π mode, for the state J P = 1 + , is confirmed. It is also confirmed that for this 1 + state the assumption of factorization of the amplitude into “production” and “decay” does not hold: the two decay modes K ∗ π and K ϱ have different polarisation properties (helicity is approximately conserved in the t -channel for the first, in the s -channel for the second). The assumption that the ( K ̄ 0 π − π 0 ) system has isospin I = 1 2 has been tested and found to hold. From the cross sections for the various J P states, assuming I = 1 2 , the cross sections for the (K − π + π − ) system are predicted and compared with the experimental ones. In general, agreement is found.
No description provided.
A partial-wave analysis has been performed on the (K − π − π + ) system produced in the reaction K − p → K − π − π + p at 10 and 16 GeV/ c . In the Q mass region it is found that the two dominant states, K ∗ π and Kπ, both in 1 + S wave, are produced with different polarisations, helicity being approximately conserved in the t -channel for K ∗ π and in the s -channel for Kπ. This is in contradiction with the assumption that the amplitude can be factorised into “production” and “decay” parts, and hence that the two amplitudes are fully coherent. The phase variation of the two states do not indicate simple resonance behaviour. It is concluded that the Q-mass enhancement is composite.
No description provided.
This paper reports studies of the reactions γp→ρ π π πp and γp→ρ ρ πp. In particular a peak is reported in the ρ ρ π mass spectrum with closely similar mass and width to those of the ω ρ π peak previously reported in the reaction γp→ω ρ πp. The ratio of production cross sections is found to be ρ ρ π/ω ρ π=0.96±0.19, in serious disagreement with the expectation from Vector Meson Dominance. A possible explanation is indicated.
No description provided.
The differential cross section has been measured at 30, 50, 80, 100, 120 and 140 GeV/ c for 0.002 < | t | < 0.04 ( GeV / c ) 2 . The results show that the π − p real part goes from negative to positive values below 80 GeV/ c . The slope parameter in the t -region measured is significantly higher than what has been found − t = 0.2 (GeV/ c ) 2 .
FROM FIT TO D(SIG)/DT AND SIGMA TOTAL FOR -T = 0.002 TO 0.04 (0.02 AT 30 GEV/C AND 0.03 AT 140 GEV/C) GEV**2.
From measurements of proton-proton elastic scattering at very small momentum transfers where the nuclear and Coulomb amplitudes interfere, we have deduced values of ρ, the ratio of the real to the imaginary forward nuclear amplitude, for energies from 50 to 400 GeV. We find that ρ increases from -0.157 ± 0.012 at 51.5 GeV to +0.039 ± 0.012 at 393 GeV, crossing zero at 280 ± 60 GeV.
No description provided.
The slope b(s) of the forward diffraction peak of p−p elastic scattering has been measured in the momentum-transfer-squared range 0.005≲|t|≲0.09 (GeV/c)2 and at incident proton energies from 8 to 400 GeV. We find that b(s) increases with s, and in the interval 100≲s≲750 (GeV)2 it can be fitted by the form b(s)=b0+2α′lns with b0=8.23±0.27, α′=0.278±0.024 (GeV/c)−2.
MOMENTUM BINS ARE APPROX 20 GEV WIDE CENTRED AT THE GIVEN PLAB EXCEPT FOR THE 9 AND 12 GEV POINTS WHICH HAVE WIDTHS OF APPROX 1 AND 4 GEV RESPECTIVELY.
About 15 000 K − Φp events have been collected in the CERN Ω′ spectrometer. A partial-wave decomposition of the K − Φ system is performed. The 1 + SO + wave is dominant. The 0 − P0 + and 2 − P0 + waves are important and show resonant behaviour at ∼ 1.83 GeV (Γ ∼ 0.25 GeV) and ∼ 1.73 GeV (Γ ∼ 0.22 GeV) respectively. The first one can be interpreted as the second radial excitation of the kaon while the second one can be identified as one of the two L mesons.
No description provided.
Forum