Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.
No description provided.
No description provided.
No description provided.
None
Axis error includes +- 0.0/0.0 contribution (?////NOT GIVEN).
Axis error includes +- 0.0/0.0 contribution (?////NOT GIVEN).
No description provided.
We have measured the differential cross section for pp and p̄p elastic scattering at √ s = 31, 53 and 62 GeV in the interval 0.05 < | t | < 0.85 GeV 2 at the CERN ISR using the Split Field Magnet detector. At 53 and 62 GeV, for 0.17 < | t | < 0.85 GeV 2 both pp and p̄p data show simple exponential behaviour in t ; at √ s = 31 GeV the data for 0.05 < | t | < 0.85 GeV 2 are consistent with a change in slope near | t | = 0.15 GeV 2 .
ERRORS CONTAIN BOTH STATISTICAL AND T-DEPENDENT SYSYEMATIC ERRORS.
No description provided.
LOCAL SLOPE PARAMETERS BASED ON QUADRATIC EXPONENTIAL FIT.
A study of ϕ-meson photoproduction by partially polarized photons of energy 20–40 GeV is reported. The production mechanism is found to conserves-channel helicity and to proceed via natural-parity exchange in thet channel. In the photoproduction of high-massK+K− states with photons of energy 20–70 GeV, there is evidence for an enhancement at a mass of 1.76 GeV with width 0.08 GeV.
No description provided.
No description provided.
No description provided.
The reactionγp→π+π−π0π0p (excludingωπ0 production) has been studied for photon energies in the range 20–70 GeV. A peak is seen in the 4π mass spectrum at ∼1.66 GeV with a width of ∼0.3 GeV which is identified with theρ′(1600). Maximum likelihood fits show that the peak is dominantly inρ±π∓π0 withB(ρ′→ρ0π0π0)/B(ρ′→ρ±π∓π0)<0.1. This indicates anI=1ρπ final-state interaction. However, no evidence is found for any resonant ρπ state such as anA1 orπ′.
AFTER OMEGA EXCLUSION.
ERROR IS DOMINANTLY SYSTEMATIC.
We have obtained a sample of 20 465 (2201) events in the channel pp→ ( Λ 0 K + )p at 50 (30) GeV/ c incident momentum with Geneva-Lausanne spectrometer at the CERN SPS. In this analysis we investigate: 1. (i) the production of N ∗ (I = 1 2 ) states in the mass region 1.6 ⩽ M ( Λ 0 K + ) ⩽ 2.6 GeV and momentum transfer 0.06 ⩽ | t | 1.0 (GeV/ c ) 2 , by studing the amplitudes and phases from a moment analysis of the decay angular distribution; 2. (ii) the contribution of the K-exchange Deck model for M ( Λ 0 K + < 2.22 GeV; 3. (iii) the double Regge exchange phenomenology for s Λ 0 K + > 5 GeV 2 and s Λ 0 K + p > 5 GeV 2 .
No description provided.
No description provided.
No description provided.
We have measured the p p differential elastic cross section at 8 momenta from 353 to 578 MeV/ c , determining, for each momentum, the ratio ρ of the real to imaginary parts of the elastic forward amplitude, the slope b of the elastic cross section and the total p p cross section σ. Our results are compared with previous experimental results and with theoretical predictions.
No description provided.
No description provided.
Numerical values supplied by M. Cresti.
The reaction K−p→K¯0π−p has been studied at 100 and 175 GeV/c and the reaction π−p→K0K−p at 50, 100, and 175 GeV/c. Both reactions are dominated by production of resonances, K*(890), K*(1430) and A2(1320), A2(2040), respectively. Production cross sections, t distributions, and decay-angular distributions are studied. Isoscalar natural-parity exchange is dominant. The energy dependence of the K* and A2 resonance production between 10 and 175 GeV/c is well described by a Regge-pole model. Our data on A2 corrects that in an earlier paper.
No description provided.
No description provided.
No description provided.
The p p elastic differential cross section at 30 GeV/ c incident momentum has been measured in a two-arm spectrometer experiment (WA7) at the CERN SPS. The | t |-range covered extends from 0.5 to 5.8 (GeV/ c ) 2 . A pronounced dip-bump structure is observed, with a sharp minimum around | t | ≈ 1.7 (GeV/ c ) 2 . The results are compared with existing p p data at lower energies and with our earlier p p data at 50 GeV/ c . A number of model predictions are discussed. We also compare the p p 30 GeV/ c differential cross section with that of pp at the same momentum. Finally, the energy dependence of the p p fixed-| t | differential cross in the incident momentum range 3.6 to 50 GeV/ c is presented.
NUMERICAL VALUES SUPPLIED BY D. IMRIE. ERROR CONTAINS BOTH STATISTICS AND SYSTEMATICS.
Results from the first PWA of the K + K − system produced by incident K − , are presented in the mass range from the threshold to 1.70 GeV. In the P and D waves only the φ and f′ mesons are observed and their production mechanism studied. A broad S wave peaking at 1.4 GeV is observed but the lack of information about its phase makes the search for new 0 ++ mesons inconclusive.
ASSUMING BRANCHING RATIO 0.486 FOR PHI --> K+ K-.
No description provided.
No description provided.
Forum