Total p−p cross-section measurements have been made at 28 momenta, in the range (0.575÷5.35) GeV/c. The cross-section decreases monotonically with increasing momentum. No important irregularity has been found.
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Interactions of 14 GeV protons with free and quasi-free nucleons are studied in nuclear emulsion. The elastic cross-section for proton-free proton collision is estimated to be (11±4) mb. The numbers of protons, charged π-mesons and K-mesons per inelastic interaction are found to be 1.24±0.09, 2.53±0.19 and 0.30±0.06, respectively. The centre-of-mass system angular distributions and the mean values of the centre-of-mass system momenta for charged secondaries are given and compared with the results of works at other energies.
No description provided.
The differential cross-section for elastic charge-exchange scattering of neutrons on protons has been measured at 8 GeV/c over forward laboratory scattering angles (0÷90) mrad (square of four-momentum transfer 0<−t<0.5 (GeV/c)2). The method utilized acoustic spark chambers and about 1900 elastic-scattering events were analysed. A value of (dσ/dΩ)lab=(20±6) mb/sr (dσ/dt=(0.93±0.28) mb/(GeV/c)2) was obtained for the forward differential cross-section and an estimated (0.06±0.03) mb for the elastic charge exchange cross-section. Both cross-sections show the decreased values expected from Pomeranchuk’s second theorem (1) when compared with results at lower energies (2). Further comparison shows that the narrow forward peak in the distribution of dσ/dt previously observed for −t<0.05, is still present at 8 GeV/c, varying in shape only slowly, if at all, with energy. For −t>0.1 however, energy dependence is apparent. The results also suggest that the interaction is spin-dependent and/or that the real parts of the scattering amplitudes in the isospin states 0 and 1 are different. Comparisons with the theoretical predictions show good agreement with the value of forward cross-section given by the Regge pole approach ofAhmadzadeh (3). The model ofRingland andPhillips (4) for single-pion exchange with absorption agrees with our results for −t<0.01 but a predicted secondary peak at −t∼0.08 is not observed.
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'2'. '3'.
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An extensive investigation of antiproton-proton interactions at 5.7 GeV/c without strange-particle production was carried out using a hydrogen bubble chamber. Cross-sections for different channels are given and discussed. The reliability of the analysis was checked using artificially generated events. The cross-sections for elastic scattering, for all processes involving annihilation, and for all other inelastic processes are respectively σel=(16.3±0.6)mb,σannlbil=(22.5±2.0)mb, σinel=(24.8±2.0)mb. TheN * 1:38 is present both in the single and multiple pion production channels. For the reaction MediaObjects/11539_2007_Article_BF02720569_f1.jpg a cross-section of (1.05±0.21) mb was obtained. Cross-sections forN * 1238 production in other channels are also given. Some indication of the presence ofI=1/2 isobars was found in the nucleon-pion and the nucleon-two-pion systems. The inelastic nonannihilation reactions were found to be strongly peripheral. The one-pion exchange model including either a form factor or corrections for absorption was applied to the reaction MediaObjects/11539_2007_Article_BF02720569_f2.jpg . Neither version of the model could correctly account for all features of the reaction. The average number of pions in the annihilation was found to be 7.3±0.6. The presence of an asymmetry in the angular distribution of the charged pions was confirmed at this energy; it is due mostly to high-energy pions. The production of ρ and ω mesons was observed in various annihilation channels. Rates of up to 80% for ρ production and up to 15% for ω production were obtained by fitting phase-space and Breit-Wigner curves to the effective-mass distributions of different channels.
No description provided.
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Elastic scattering, single-pion and deuteron production have been investigated. The cross-section for elastic scattering is σelastic = (13.5±0.3) mb. The angular distribution has been fitted to dσ/d|t|=(dσ/d|t|)0 e −bt in the region of low values oft. The best fit givesb=(6.7±0.5) (GeV/c)−2 and (dσ/d|t|)0=(91±5) mb(GeV/c)−2. The cross-sections for ppπ0, pnπ+ reactions are respectively (2.6±0.3) mb and (9.7±0.4) mb. These reactions are dominated by the (3/2, 3/2) nucleonpion isobar production and by forward backward collimation of the nucleons. The production rates for the isobars ++1238 , +1238 , +1500 have been estimated, taking into account the experimental peripheral behaviour of the interaction. In the pnπ+ reaction they are (50±2)%; (10±3)%; (4±3)%. In the ppπ+ reaction the production of ++1238 is estimated to be (45±10)%. The dπ+ and dπ+π+π- reaction cross-sections are respectively (0.03±0.01) mb, and (0.04±0.01) mb.
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Elastic and inelastic 19.8 GeV/c proton-proton collisions in nuclear emulsion are examined using an external proton beam of the CERN Proton Synchrotron. Multiple scattering, blob density, range and angle measurements give the momentum spectra and angular distributions of secondary protons and pions. The partial cross-sections corresponding to inelastic interactions having two, four, six, eight, ten and twelve charged secondaries are found to be, respectively, (16.3±8.4) mb, (11.5 ± 6.0) mb, (4.3 ± 2.5) mb, (1.9 ± 1.3) mb, (0.5 ± 0.5) mb and (0.5±0.5)mb. The elastic cross-section is estimated to be (4.3±2.5) mb. The mean charged meson multiplicity for inelastic events is 3.7±0.5 and the average degree of inelasticity is 0.35±0.09. Strong forward and backward peaking is observed in the center-of-mass system for both secondary charged pions and protons. Distributions of energy, momentum and transverse momentum for identified charged secondaries are presented and compared with the results of work at other energies and with the results of a statistical theory of proton-proton collisions.
No description provided.
Ilford G-5 emulsions were exposed to an external, 3.5 GeY proton beam of the Berkeley Bevatron. A total of 1200 nuclear interactions of beam protons was located, of which 128 were identified as protonproton collisions. Multiple scattering, blob density, range and angle measurements were employed to determine the cross-sections for elastic and inelastic interactions as well as the identities and center-of-mass system momenta and scattering angles of secondaries from inelastic proton-proton interactions. This analysis indicates a cross-section of (8.0±2.4) mb for elastic events, (24.1±2.9) mb for two-prong inelasitc events, (7.9±1.4)mb for four-prong events and (0.6±0.3) mb for sixprong events. The mean charged pion multiplicity in inelastic interactions is 1.5±0.2 and corresponds to an average degree of inelasticity of 0.45 ±0.06. Center-of-mass system angular distributions of charged secondaries from inelastic events display a peaking for small scattering angles which is most pronounced for protons and pions from events with low secondary multiplicity. Momentum and transverse momentum distributions of secondary protons and pions from inelastic events are presented and compared with the results at other energies. The angular distribution of elastically scattered protons is found to be in fair agreement with that predicted by a uniform optical model of radius 1.25-10-13 cm and opacity 0.66.
No description provided.
A bubble chamber investigation of π−+p elastic scattering at 1 200 MeV (K.E.) is reported. The total and differential cross-sections are determined. By extrapolation of the angular distribution, the 0° cross-section is derived and compared with the results obtained with the help of the dispersion relations and the optical theorem. The forward peak is investigated in terms of diffraction scattering and a value for the optical radius is derived.
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Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum in proton-proton collisions at sqrt(s)=7 TeV are reported. Data collected by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 4.6 fb-1 are used. Good agreement is observed between the data and the Standard Model predictions. The results are translated into exclusion limits on models with large extra spatial dimensions and on pair production of weakly interacting dark matter candidates.
95% CL observed and expected upper limits on M_D as a function of the number of extra-dimensions considering LO signal cross sections. The impact of the +-1sigma theoretical uncertainty on the observed limits and the expected +-1sigma range of limits in the absence of a signal are also given.
95% CL observed and expected upper limits on M_D as a function of the number of extra-dimensions considering NLO signal cross sections. The impact of the +-1sigma theoretical uncertainty on the observed limits and the expected +-1sigma range of limits in the absence of a signal are also given.
95% CL observed and expected upper limits on M_* for spin-independent (D1) WIMP models. The impact of the +-1sigma theoretical uncertainty on the observed limits and the expected +-1sigma range of limits in the absence of a signal are also given.
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