The polarization parameter in proton-proton elastic scattering has been measured at an incident momentum of 7.9 GeV/ c and four-momentum transfers in the range 0.9 < | t | < 6.5 (GeV/ c ) 2 using a high intensity unpolarized proton beam incident on a polarized proton target. The angle and momentum of the forward scattered protons were measured with a magnet spectrometer and scintillation counter hodoscopes and the angle of the recoil proton was measured using similar hodoscopes. A clean separation between the elastic scattering from free hydrogen and that coming from inelastic interactions and from interactions with complex nuclei in the target was obtained. The polarization shows substantial structure rising from zero at | t | = 1.0 (GeV/ c ) 2 to a maximum at | t | = 1.7 (GeV/ c ) 2 and then falling to zero at | t | = 2.0 (GeV/ c ) 2 . There is evidence of a further peak at | t | = 2.8 (GeV/ c ) 2 . Above | t | = 3.25 (GeV/ c ) 2 the polarization is small and consistent with zero. A comparison of these data with data obtained at other beam momenta shows that the polarization parameter has a strong momentum dependence.
No description provided.
Cross-section, angular distribution and polarization measurements are presented at six incident π + energies for the reaction π + p → K + Σ + . Results at already studied energies are compatible with existing data and roughly agree with predictions of partial-waves analyses. However, new results around 1.920 GeV are in disagreement with such predictions, casting some doubt on the determination of decay branching ratios of the T = 3 2 isobars around this mass into K + Σ + .
No description provided.
No description provided.
No description provided.
The inclusive cross section and the average multiplicity are evaluated for most of the charged ( π ± , p, K ± ) and neutral (γ, π 0 , K 0 , K 0 , Λ, Λ , n ) particles produced in 32 GeV/ c K − p interactions; corresponding results are obtained for each charged topology separately. New results are given for the total charged multiplicity cross sections. The average longitudinal momentum of neutrals is found to be roughly equal to that of charged particles. The π + and π − multiplicity distributions are reconstructed and compared to the π 0 and to the total charged multiplicity distributions.
No description provided.
Axis error includes +- 30/30 contribution (SYSTEMATIC ERROR FOR K0 MULTIPLICITY, WHICH IS EVALUATED FROM 2 ASSUMPTIONS: ALL K0'S COME FROM THE FINAL STATES (N K 2AK PIONS) OR (LAMBDA/SIGMA K AK PIONS) AND CHARGE DISTRIBUTION IN THESE FINAL STATES OBEYS A STATISTICAL ISOSPIN MODEL OF F.CERULUS,NC 19, 528. ALSO ASSUMED THAT SIG(K+)=SIG(KO). VALUES OF SIG(XI-) AND RATIOS SIG(SIGMA+)/SIG(LAMBDA), SIG(SIGMA-)/SIG(LAMBDA) ARE TAKEN FROM 14.3 GEV EXPERIMENT LOUEDEC 76,NC 41A, 166, STATISTICAL ERRORS BEING DOUBLED. FOR ALL ANTIBARYONS ASSUMED THAT SIG(ANTIBARYON)/SIG(BARYON)=SIG(ANTILAMBDA)/SIG(LAMBDA) =0.046+-0.020. SLOW PROTONS WITH PLAB < 1.2 GEV/C ARE IDENTIFIED, AN ESTIMATE FOR FAST PROTON PRODUCTION IS TAKEN FROM FACCINI 77,NP B127, 109).
Axis error includes +- 30/30 contribution (SYSTEMATIC ERROR FOR K0 MULTIPLICITY, WHICH IS EVALUATED FROM 2 ASSUMPTIONS: ALL K0'S COME FROM THE FINAL STATES (N K 2AK PIONS) OR (LAMBDA/SIGMA K AK PIONS) AND CHARGE DISTRIBUTION IN THESE FINAL STATES OBEYS A STATISTICAL ISOSPIN MODEL OF F.CERULUS,NC 19, 528. ALSO ASSUMED THAT SIG(K+)=SIG(KO). VALUES OF SIG(XI-) AND RATIOS SIG(SIGMA+)/SIG(LAMBDA), SIG(SIGMA-)/SIG(LAMBDA) ARE TAKEN FROM 14.3 GEV EXPERIMENT LOUEDEC 76,NC 41A, 166, STATISTICAL ERRORS BEING DOUBLED. FOR ALL ANTIBARYONS ASSUMED THAT SIG(ANTIBARYON)/SIG(BARYON)=SIG(ANTILAMBDA)/SIG(LAMBDA) =0.046+-0.020. SLOW PROTONS WITH PLAB < 1.2 GEV/C ARE IDENTIFIED, AN ESTIMATE FOR FAST PROTON PRODUCTION IS TAKEN FROM FACCINI 77,NP B127, 109).
From an experiment done with the CERN Omega spectrometer, triggered by a fast forward proton device, we present results on the differential cross section d σ d u for π − p backward elastic scattering. The d σ d u distribution agrees with an A e Bu law. The compilation of existing results shows a discrepancy between results but the ( d σ d u ) u=0 data fit perfectly an s 2 α 0 −2 dependence, as predicted by a single Δδ Regge trajectory exchange. A search for the reaction π − p → d p , with a fast forward deuteron, which can be produced by a double-baryon exchange mechanism, gives cross-section upper limits of ∼1% of the backward elastic cross section.
UMIN IS 0.0446 GEV**2.
UMIN IS 0.0333 GEV**2.
D(SIG)/DU FITTED FOR 0 < -U < 0.75 GEV**2 TO GIVE SLOPE/INTERCEPT.
An enhancement in the (K − π + ) mass distribution at 1871 ± 10 MeV with full width of 285 ± 40 MeV is observed in the charge-exchange reaction K − p → K − π + n at 10 and 16 GeV/ c . The energy dependence of its cross section, the shape of the differential cross section d σ /d t and the decay angular distributions are consistent with a production mechanism by pion exchange. No significant enhancement at the same mass is seen in the non-charge exchange reaction K − p → (K π ) − p. The experimental evidence is reviewed and it is suggested that there may be more than one K ∗ enhancement in the 1700–1900 mass region.
FOR ALL EVENTS WITH 1.7 < M(K- PI+) < 2 GEV. NO FORWARD DIP. 'THETA CUT'.
THE 14.3 GEV/C POINT IS FROM ANALYSING THE DATA OF M. SPIRO ET AL., PL 60B, 389 (1976) IN THE SAME WAY. 'THETA-CUT'.
Qausi-elastic ω production by ep scattering in the kinematic region 0.3. < Q 2 < 1.4 GeV 2 and 1.7 < W < 2.8 GeV was studied using a streamer chamber at DESY. The production angular distribution for γ V p → ω p has a strong non-peripheral component for W < 2 GeV. The ω production cross section falls by a factor of 4 as W changes from 1.7 to 2.8 GeV. In contrast the cross section for ω production with | t | < 0.5 GeV 2 is W independent between 1.7 and 2.8 GeV and for W > 2.0 GeV consistent in both W and Q 2 dependence with the predictions of a model based on one-pion exchange and diffraction.
FOR ALL T-VALUES. THE GAMMA* P TOTAL CROSS SECTION WAS TAKEN FROM A FIT TO THE DATA OF S. STEIN ET AL., PR D12, 1884 (1975). 'PPD'.
'PPD'. PERIPHERAL OMEGA PRODUCTION.
No description provided.
A measurement of the polarization parameter P 0 in pp elastic scattering has been made at 24 GeV/ c over the range | t | = 0.1 to 0.9 (GeV/ c ) 2 , positive, falling to zero around | t | = 0.8 (GeV/ c ) 2 . For the range 0.1 ⪕ |t| ⪕ 0.4 GeV /c) 2 , P 0 is constant at about 0.03.
Axis error includes +- 5/5 contribution (SYS-ERR DUE MAINLY TO UNCERTAINTY IN KNOWLEDGE OF ABSOLUTE VALUE OF TARGET POLARIZATION).
Differential cross sections for elastic K + p scattering have been measured at nineteen momenta between 0.7 and 1.9 GeV/ c . The data represent between 10 thousand and 20 thousand elastic events at each momentum and cover a wide range of scattering angles ( −0.98 ≲ cos θ ∗ ≲ 0.95 ). A computer controlled system of scintillation counters and acoustic spark chambers was used to detect the elastic events. Various internal consistency checks indicate that the absolute normalization of the data is accurate to within 2–3%. The cross sections show a smooth transition from an isotropic angular distribution to a dominant forward peak over the range covered by the experiment. Phase-shift analyses including these results show little evidence for a direct-channel resonance, and fitting the results by t - and u -channel exchange processes alone gives a good fit.
No description provided.
No description provided.
No description provided.
The ratios of K+, K−, p, and p¯ yields to pion yields at transverse momenta (p⊥) ranging from 0.77 to 6.91 GeV/c arepresented for 200-, 300-, and 400-GeV p−p and 400-GeV p−d collisions. The dependences of the particle ratios on p⊥ and the scaling variable x⊥=2p⊥s are discussed.
No description provided.
No description provided.
No description provided.
The total cross section for hadron production by high-energy photons has been measured from a number of nuclei ranging from hydrogen to uranium. Some shadowing is observed at a level considerably less than predicted by conventional vector-meson dominance but consistent with a modified theory. The energy dependence predicted by vectormeson dominance is observed. The shadowing in heavy nuclei shows a smooth transition from electroproduction to photoproduction.
No description provided.
Forum