Elastic scattering and coherent single pion production in proton-helium interactions at 18.6 GeV/c

Proton-helium elastic scattering and coherent single-pion production have been studied at 18.6 GeV/c in the four-momentum transfer region (?0.06, ?0.17) GeV/c². The elastic t-distribution has a somewhat steeper slope than is predicted by the Glauber approximation. The invariant-mass distribution of the Nπ system agrees with the double Regge-pole model except at about 1.65 GeV/c² where an enhancement presumably due to N¹ resonances is seen. The model also predicts the correct magnitude of the slope for nπ⁺α events. By using our cross sections at t′ = ?0.06 (GeV/c)² where the impulse approximation should be valid, the isospin-zero exchange elementary cross section for the nπ⁺ production is evaluated. The inelastic angular distributions are consistent with several spinparity states contributing at all Nπ masses.     

Experimental investigation of charge-exchange processes involving a target proton in <Superscript>16</Superscript>O<Emphasis Type="Italic">p</Emphasis> collisions at a momentum of 3.25 GeV/<Emphasis Type="Italic">c</Emphasis> per nucleon

For the first time, charge-exchange processes involving a target proton in ¹⁶Op collisions at a momentum of 3.25 GeV/c per nucleon are studied under conditions of 4π geometry. New data on the mean multiplicities fragments and pions, as well as on inelastic cross sections for topological channels of the fragmentation of an oxygen nucleus in charge-exchange reactions involving a target proton that either are accompanied or are not accompanied by charge transfer to a projectile nucleus, are presented. It is shown that, in ¹⁶Op interactions at high energies, charge transfer from a target proton to a projectile nucleus proceeds predominantly via inelastic proton scattering on a neutron of the oxygen nucleus.     

A study of final state deuteron events in 1.825 GeV/c pd interactions

The study of pd → ndπ⁺ and pd → pdπ^O reactions shows that the “slow deuteron” inelastic events are dominated by peripheral processes. Box diagrams are presented for the production mechanism of the 2.2 GeV/c² dπ enhancements. Evidence is presented that for ‘fast deuteron’ events d¹⁺⁺ and d¹⁺ resonances at 2.375 ± 0.010 GeV/c² with a width of 0.075 ± 0.015 GeV/c² are produced via baryon exchange. The elastic events have been compared with Glauber multiple scattering theory with reasonable agreement.     

A study of trimuon events in 280 GeV muon interactions

In 280 GeV μ⁺ iron interactions the inelastic production of muon pairs has been observed in excess of QED processes. For energies greater than 20 GeV deposited in the target calorimeter the interactions are found to be mainly hadronic. Cross sections are presented for this process in the mass range 1?2.5 GeV/c² and in the kinematic regions covered by the apparatus acceptance. The data are in good agreement with a photon-gluon fusion model for charmed particle production.     

Multiplicity distributions in rapidity intervals forp-p andp-nucleus interactions at 200 GeV

Multiplicity distributions of charged particles produced in proton-proton, proton-argon and proton-xenon inelastic collisions at 200 GeV/c in various rapidity intervals are presented. Nuclear target data are analysed separately for the forward and the backward hemispheres. Results of a similar analysis for only negative particles are shown. The data are well parametrized in terms of negative binomial distributions. However, such a parametrization fails in describing thep-nucleus multiplicity distributions of charged particles for large rapidity intervals comprising both hemispheres. Parameters characteristic for the clan model of Giovannini and Van Hove are also presented.     

Neutral kaon production in K+p interactions at 32 GeV/c

The production of neutral kaons in the reaction K⁺p → Kⁿ + X is studied at the incident momentum of 32 GeV/c. Inclusive cross sections and single-particle distributions are presented and compared with the data at lower energies. The total inclusive cross section amounts to 7.9 ± 0.3 mb at 32 GeV/c and is significantly higher than at lower energies due to the rapid rise of multikaon production. The fraction of Kⁿ's coming from the decay of the K¹ resonances stays roughly constant with energy between 8.2 and 32 GeV/c. In the central and beam fragmentation regions the single-particle distributions reveal no energy dependence between the 16 and 32 GeV/c data in contrast with the behaviour at lower energies, while in the proton fragmentation region the data are compatible with the trend observed at lower energies and with theoretical expectations.     

The pion-nucleon scattering amplitudes at 40 GeV/c

The helicity amplitudes for isospin-0 exchange are determined at 40 GeV/c. For isospin-1 exchange only partial information is obtained. The model-independent analysis is extended to the four-momentum transfer interval from t = 0 to t = ?0.6 (GeV/c)². One of the two solutions presented has a behaviour similar to the previous results at lower energy.     

Charge transfer and rapidity gap analysis inp(π+)n interactions at 195GeV/c

We present charge transfer probabilities between CM hemispheres inpn and π⁺ n interactions at 195 GeV/c. The relative probabilities for charge exchanges |ΔQ|>1 as a function of rapidity gap length,r, are given. Both results are compared with those of π^? p interactions at 200GeV/c. The average ofr, viz. <r>, is given as a function of the gap number and of ΔQ for various multiplicities, and the reduced average gap lengths <r>/y _max forpn interactions are compared with data at a lower energy.     

Momentum dependence measurements of the np → pn charge - exchange peak between 1 and 2 GeV/c

21 differential cross section measurements of the np → pn charge-exchange reaction have been carried out at the synchrotron Saturne (Saclay), for incident neutron momenta between 1 and 2 GeV/c and in the squared four-momentum transfer range 0 ? ?t ? 0.4 (GeV/c)². The π exchange peak is seen at all the incident momenta. The s dependence of the very forward slope of this peak shows weak structures near the threshold of inelastic channels.     

The charge exchange pp → nn at 5.0 and 7.76 GeV/c near the forward direction

The differential cross section for the charge exchange $\text{p}\text{p}\text{→}\text{n}\text{n}$ has been measured with high statistics at 7.76 GeV/c and at 5.0 GeV/c. The 7.76 GeV/c data show a very narrow [Δt ? 0.01 (GeV/c)²] forward peak superposed on a slow exponential fall-off.     

Study of Δ production in the reaction πp→ππp at 13.1 GeV/c

We have measured the production and decay angular distributions of the reaction π⁺p→π^OΔ⁺⁺ at 13.1 GeV/c incident momentum. For −t > 0.1 (GeV/c)² the data is well described by M1 ?-exchange models, the best results being obtained from a weak cut model with a wrong signature nonsense zero. For −t < 0.1 (GeV/c)² there is evidence for the existence of other exchange mechanisms.     

Polarization in K+n charge exchange scattering between 0.851 GeV/c and 1.351 GeV/c

The polarization parameter for K⁺n charge exchange scattering has been measured at five momenta between 0.851 GeV/c and 1.351 GeV/c for centre of mass angles $\text{?0.8 <}\text{cos}\text{θ}{}^1\text{< 0.8}$. Results from a phase shift analysis incorporating these results are presented. No Z¹ resonances are observed.     

Forward and backward multiplicities inK − p interactions at 110 GeV/c

Multiplicity distributions and correlations between charged particles in the forward and back-ward c.m. hemispheres are studied inK ^?p interactions at 110 GeV/c and compared with other data on mesonnucleon scattering. The interpretation in terms of a simple quark-parton picture assuming that the forward multiplicity is dominated by quark fragmentation and the backward multiplicity by diquark fragmentation is supported by the experimental fact that the forward and the backward mean multiplicities are approximately equal to half of thee ⁺ e ^? andpp multiplicities, respectively. The 110 GeV/cK ^?p data show significant correlations between the numbers of slow forward and slow backward particles, whereas the multiplicities of fast forward and fast backward particles are independent.     

Momentum spectra of secondary particles produced in proton-proton collisions at 14.2, 19.2 and 24.0 GeV/c

Results on charged particle yields in proton-proton collisions at 14.2, 19.2 and 24.0 GeV/c for secondary momenta above 4 GeV/c and lab angles between 10 and 150 mrad are reported. Cross sections for inclusive reactions involving the production of π^± K^±, p and $\text{p}$ are presented. The general features of the dependence of the data on transverse and longitudinal momentum, missing mass, and four-momentum transfer are described and the approach to limiting distributions in the 10 to 30 GeV energy range is discussed.     

Multiparticle emission in the interactions of hadrons with complex nuclei at incident momenta from 2 to 4 GeV/c

The charged secondary particles emitted in inelastic reactions of 4 GeV/cπ⁺ and π^? with the nuclei Be, Cu and Ta are thoroughly studied in their multiplicities, particle correlations and the distributions of kinematical variables, with the 1 m hydrogen bubble chamber into which the three nuclear target plates were installed. The numbers of charged secondaries emitted in the π^?(2.3 GeV/c), π⁺(2 GeV/c) and p(4 GeV/c) reactions are also investigated. From these data, characteristic features of the multiplication process of secondaries in nuclear matter are clarified. The experimental results are compared with the calculation of an intra-nuclear cascade model which takes into account the process of pion absorption by two-nucleon clusters in the nucleus. It is found that the experimental results on the properties of charged secondaries are consistently explained by the model. The model can also give an account of the experimental finding that fairly high momentum protons are emitted from the heavier nuclei into the backward hemisphere in the lab system.     

ϱ and A2 amplitudes in K±N charge exchange using fixed t analyticity

Amplitudes corresponding to ? and A₂ quantum number exchanges in K^±N charge exchange scattering are obtained from data in the few GeV region using an analysis based on fixed t analyticity in the form of fixed t dispersion relations and finite-energy sum rules. Comparisons are made with amplitude analyses at 6 GeV/c and some specific high-energy models.     

Measurement of the tensor analyzing power A yy in the inelastic scattering of 4.5-GeV/c deuterons on beryllium at an angle of 80 mrad

The tensor analyzing power A _yy and the vector analyzing power A _y for the inelastic scattering of 4.5-GeV/c deuterons on beryllium nuclei at angle of about 80 mrad are measured in the vicinity of baryon-resonance excitation. These new data, presented as a function of t, comply well with the results of previous 4.5-, 5.5-, and 9-GeV/c measurements at zero angle in overlapping regions of t; all available data are described by a unified dependence on |t| upto about 0.9 (GeV/c)². The experimental results are compared with the results of calculations performed within the multiple-scattering model and the model involving omega-meson exchange in the t channel.     

Koba-Nielsen-Olesen scaling

A correct version of Koba-Nielsen-Olesen (KNO) scaling is described in detail for multiplicity distributions. Some statements on the violation of KNO scaling that are based on an erroneous interpretation of experimental data are discussed. An accurate comparison with data is presented for the distributions of negatively charged particles originating from electron-positron annihilation at $\sqrt s = 3 - 161GeV$ , from inelastic proton-proton collisions at p _lab=4.5–520 GeV/c, and from nucleus-nucleus collisions at p _lab=4.5–520 GeV/c per projectile nucleon. Data on proton-antiproton interactions at $\sqrt s = 546GeV$ are also considered.     

Amplitude analysis of πN charge exchange at large momentum transfer

We have found evidence for the right-signature zero at t ≈ ?1.5 (GeV/c)² and the second wrong-signature zero at t ≈ ?2.5 (GeV/c)² in the helicity flip ?-Regge-pole exchange from an amplitude analysis of πN charge exchange extended to large momentum transfer. Reconstruction of the imaginary part of the nonflip amplitude suggests a remarkable degree of Regge behaviour out to large ?t. Confirmation of such behaviour would undermine the basic features of absorptive cut models.     

Ultra heavy fermion bound states via Higgs exchange

We study the characteristic features of the ultra heavy fermion bound state via Higgs exchange. The constraint under which such a bound state occurs is presented. For a typical example of Higgs and fermion mass, M_H≅ 100 GeV / c² and M_F≅ 700 GeV/c², the wave function at the origin of the bound states via Higgs exchange becomes about 100 times larger than that via gluon exchange.