Results are presented on π + p and K + p elastic scattering at 250 GeV/ c , the highest momentum so far reached for positive meson beams. The experiment (NA22) was performed with the european hybrid spectrometer. The π + p elastic cross section stays constant with energy while the K + p cross section increases.
No description provided.
No description provided.
ERRORS IN ELASTIC CROSS SECTIONS INCLUDE SYSTEMATIC ERRORS.
We have measured small angle elastic pion-proton scattering in 40 and 50 GeV c π − beams at Serpukhov. Analysis of the data in the Coulomb interference region yields a value for the ratio of the real to the imaginary part of the strong amplitude, ϱ (0)=−0.074 ± 0.033 at 40 GeV/ c and ϱ (0)=−0.006 ±0.026 at 50 GeV/ c
STATISTICAL ERRORS ONLY.
STATISTICAL ERRORS ONLY.
We have measured elastic pion-proton scattering in a 50 GeV/ c π − beam at the 76 GeV proton synchrotron in Serpukhov. Data are presented for four-momenta transfer squared in the range 0.03 < t < 0.4 (GeV/ c ) 2 .
SLOPE IS 9.1, +0.2, -0.4 GEV**-2 (INCLUDING SYSTEMATIC ERRORS).
The contradiction of the σ term of pion-nucleon scattering as deduced from the Karlsruhe-Helsinki phase shifts with the smaller value calculated by the chiral perturbation theory of QCD is well known. In an effort to clarify the discrepancy we have determined the real part of the isospin-even forward-scattering amplitude of pion-nucleon scattering at a pion energy Tπ=54.3 MeV by measurement of the elastic scattering of positive and negative pions on protons in the Coulomb-nuclear interference region. The deduced value is in agreement with the prediction of the Karlsruhe-Helsinki phase-shift analysis for that energy. The resulting large value of the σ term may be interpreted as being due to the influence of s¯s sea pairs even at large distances (small Q2) as previously suggested by the European Muon Collaboration measurement of deep-inelastic scattering of polarized muons on polarized protons.
No description provided.
Elastic π−+p differential cross-section data are presented at the incident-pion momenta 1.72, 1.89, 2.07, 2.27 and 2.46 GeV/c. Resonant behaviour in the coefficients of a Legendre polynomial expansion indicates G- or H-wave resonance. Further analysis using an energy-dependent parametrization of G- and H-waves shows the results to be compatible with the 7−/2 assignment for the , but equally acceptable solutions are obtained with the inclusion of an additional 9+/2 resonance contribution.
No description provided.
No description provided.
No description provided.
Differential cross sections have been measured for p¯p→π−π+ (1) and its line-reversed partner π+p→pπ+ (2) in the range tmin>t>−1.5 (GeV/c)2 at 6 GeV/c. Clear structure is seen in the differential cross section for Reaction (1) at t∼−0.4 (GeV/c)2. However, this feature is quite different from the striking dip seen in (2) at t∼−0.15 (GeV/c)2, indicating a failure of line reversal and disagreement with simple Regge models.
No description provided.
Measurements of complete angular distributions of elastic K + p scattering at closely spaced incident momenta from 1368 to 2259 MeV/ c are presented and discussed. A PDP-8 computer controlled system of scintillation counters and core-readout wire spark chambers was used for the detection of elastic events. Diffractive behaviour is already present at the lowest measured momentum and becomes more prominent as the incident momentum increases. An expansion of the angular distributions in terms of Legendre polynomials shows no marked structure of the expansion coefficients as functions of the incident momentum. Our measurements can be adequately described by a number of existing phase shift solutions within 5% of their published values. Also Regge pole extrapolations represent our data satisfactorily.
No description provided.
No description provided.
No description provided.
The Fermilab hybrid 30-in. bubble-chamber spectrometer was exposed to a tagged 147-GeV/c positive beam containing π+, K+, and p. A sample of 3003 K+p, 19410 pp, and 20745 π+p interactions is used to derive σn, 〈n〉, f2cc, and 〈nc〉D for each beam particle. These values are compared to values obtained at other, mostly lower, beam momenta. The overall dependence of 〈n〉 on Ea, the available center-of-mass energy, for these three reactions as well as π−p and pp interactions has been determined.
No description provided.
No description provided.
No description provided.
Elastic diffraction scattering of π − , K − and p on protons has been measured at 25 and 40 GeV/c at the Serpukhov Proton Accelerator. Differential elastic cross sections and diffraction slopes are presented in the momentum-transfer interval 0.07–0.80 (GeV/ c ) 2 and compared with existing data at lower energies.
No description provided.
No description provided.
No description provided.
Results are presented on elastic scattering of 10.1 GeV/ c K − mesons on protons, based on a sample of 16 261 kinematically-fitted bubble-chamber events. The differential cross section is given over the | t |- range of 0.06 to 2.5 GeV 2 and is fitted with the expressions a e bt , A e Bt + Ct 2 and ( P e Qt + Re St ) over various intervals of t . The results are compared with those of other experiments at nearby energies. Upper limits of | α | < 0.28 and σ B < 0.4 μ b (both at a 90% confidence level) are given for the ratio of real to imaginary part of the forward-scattering amplitude and the backward-elastic-scattering cross section, respectively.
No description provided.
ERROR INCLUDES STATISTICAL ERROR AND ERROR IN TOTAL CROSS SECTION USED FOR NORMALIZATION. EXTRAPOLATION OF D(SIG)/DT TO T=0 PROVIDES ABOUT 0.5 PCT UNCERTAINTY.
NO BACKWARD EVENTS OBSERVED. LARGEST ANGLE EVENT SEEN WAS AT 64 DEG (-T = 2.33 GEV**2).
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