Charge asymmetry at large pT in inelastic pp reactions at 22.4 GeV/c

Charge asymmetry in $\text{p}\text{p}$ reactions at 22.4 GeV/c is investigated as a function of transverse momentum in the c.m. rapidity interval |y¹| < 1. The charge asymmetries in the forward and backward directions are increasing with increasing transverse momentum. The increase seems to be present both in annihilation and non-annihilation processes.     

Model for high-energy baryon-antibaryon annihilation

A model for annihilation is presented, based on a simple multiperipheral interpretation of the corresponding dual unitarity diagrams. The model exactly conserves internal quantum numbers and leads to characteristic correlations and leading particle effects associated with the topology of the dominant diagrams. Uncertainties about non-leading terms prevent a direct comparison with annihilation data at low energies, but a fit to high-energy data on $\text{p}\text{p}\text{-}\text{pp}$ cross-section differences, motivated by the similarities between the differences studied and genuine annihilation data where these can be compared, shows excellent agreement when the mesonic objects produced in the model are taken to be clusters of the same type as those produced in non-annihilation processes.     

NN scattering below 300 MeV due to quark rearrangement annihilation and one-boson exchange

A microscopic $\text{N}\text{N}$ potential is presented where the annihilation effect is described by the quark rearrangement model and the one-boson-exchange contribution is further added. Gross features of $\text{p}\text{p}$ scattering observables are described by the potential with modification by a phenomenological repulsion at short distances.     

Comparison of the reaction pp → K0K0 at rest in hydrogen and deuterium. A test of S-state annihilation dominance

From the comparison of the frequency of antiproton annihilation at rest in two mesons in H₂ and D₂, the dominance of S-wave in $\text{p}\text{p}$ annihilation at rest is confirmed, the P-wave contribution being less than 6% at the 95% confidence level. The apparent discrepancy between the channels $\text{p}\text{p}\text{→}\text{K}{}^0\text{K}{}^0$ and $\text{p}\text{p}\text{→ππ}$ is due to the strong dependence of the annihilation dynamics from the angular momentum.     

The forward-backward spectator asymmetry in low-energy pD annihilation

The forward-backward asymmetry of spectators in low-energy $\text{p}$D annihilation is shown to be due to Re f($\text{p}$p). The energy dependence of the latter can be described in terms of a broad $\text{p}$p resonance with mass ≈ 1980 MeV.     

Antiproton-neutron interactions at 100 GeV/c

From an exposure of the 30-inch deuterium filled bubble chamber to a 100 GeV/c antiproton-enriched beam at FNAL, we have calculated the topological cross sections for antiproton-neutron interactions with three or more charged particles in the final state. A comparison of our data with pn data at the same momentum allows us to estimate the annihilation contribution to each multiplicity, and hence calculate the average value, and width, of the annihilation multiplicity distribution. Our results are consistent with those from $\text{p}\text{p}$ data at 100 GeV/c, but depart from the trend of lower-energy $\text{p}\text{p}$ data.     

Author index to volume 44B

Evidence is presented to show that the gross features of the pion distributions in $\text{p}$p and $\text{e}$e annihilation are essentially the same.     

General features of the pp interaction at 12 GeV/c

Simple inclusive cross sections for $\text{p}\text{p}$ interactions at 12 GeV/c are given. The data cover prong cross sections, V⁰ production and resonances. Separation has been made into annihilation and non-annihilation modes. Some implications of the data are discussed. It is pointed out that the ratios of cross sections for $\text{?}{}^0\text{π}{}^{\mathrm{?}}$ production are independent of incident antiproton momentum in $\text{p}\text{p}$ annihilation processes, and that data at the highest available pp energies (ISR) tend to the same value.     

Some salient features of antiproton-nucleon annihilations

We have studied pion production data from $\text{p}\text{p}$ and $\text{p}\text{n}$ annihilation between 1.51 and 2.90 GeV/c. The gross features of the data indicate that mechanism for antiproton-nucleon annihilations are primarily of statistical nature.     

Multiplicities of secondary hadrons produced in vp and vp charged current interactions

In an experiment with the hydrogen bubble chamber BEBC at CERN multiplicities of hadrons produced in νp and $\text{v}\text{p}$ interactions have been investigated. Results are presented on the multiplicities of charged hadrons and neutral pions, forward and backward multiplicities of charged hadrons and correlations between forward and backward multiplicities. Comparisons are made with hadronic reactions and e⁺e^? annihilation. In the framework of the quark-parton model the data imply similar charged multiplicities for the fragments of a u- and a d-quark, and a larger multiplicities for the fragments of a uu- than for a ud-diquark. The correlation data suggest independent fragmentation of the quark and diquark for hadronic masses above ～ 7 GeV and local charge compensation within an event.     

Quantum statistics and isospin invariance

The level density of an ideal Bose or Fermi gas is written in terms of usual phase-space integrals taking isospin conservation into accoutt. This cluster decomposition includes quantum statistics corrections between equal as well as unequal charge states of the considered particles. The isospin weights are given. These results are used to formulate a simple isospin-invariant statistical bootstrap model with Bose statistics. In the framework of this model the production of neutral pions in e⁺e^? and $\text{N}\text{N}$ annihilation is investigated.     

Analysis of two-prong events in antiproton-proton interactions at 5.7 GeV/c

A study of elastic scattering, one-pion production and annihilation reactions in $\text{p}$p interactions at 5.7 GeV/c was carried out, from the two-prong events, obtained in the hydrogen bubble chamber exposed at CERN.Single particle distributions for the reactions $\text{pp}\text{→}\text{pp}\text{π}{}^0\text{,}\text{p}\text{p}\text{→}\text{p}\text{n}\text{π}{}^{\mathrm{+}}$ and $\text{p}\text{p}\text{→}\text{p}\text{n}\text{π}{}^{\mathrm{?}}$ are presented. The study of the squared momentum transfer distributions with and without charge exchange in the cross channel shows different behavior of the slope parameters versus the mass of the produced (Nπ) system. The cross sections for isobar production and for diffractive dissociation in the one-pion production reactions are obtained from a detailed Dalitz plot analysis. The results of the analysis of the decay angular distributions for the N(1510) and for the N(1680) produced in these reactions are in agreement with $\text{J =}\text{3}\text{2}\text{and}\text{J =}\text{5}\text{2}$ assignment, respectively. The cross sections of the annihilation reactions $\text{p}\text{p}\text{→ π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{and}\text{p}\text{p}\text{→ π}{}^{\mathrm{+}}\text{π}{}^{\mathrm{?}}\text{π}{}^0$ are determined. Finally, we give some as aspects of the mass distributions for the last reaction.     

Evidence for narrow bound states related to the pp system

The γ-ray spectrum accompanying the p$\text{p}$ annihilation at rest has been measured with a large NaI(Tl) spectrometer. Three γ-lines have been observed with energies of 183 ± 7 MeV, 216 ± 9 MeV, and 420 ± 17 MeV at confidence levels of 99.0%, 97.5%, and 98.2%, respectively. The width of the lines corresponds to the detector resolution.     

Intermediate annihilation states in antiproton-nucleus scattering

We study the annihilations on nuclei paying special attention to the role of unitarity in these processes. Analysing the intermediate states, it is shown that the annihilation cross section is much larger than the difference $\text{p}\text{?}\text{A ?}\text{p}\text{A}$ and for heavy nuclei is even larger than the non-annihilation cross section. The singular way in which unitarity works in annihilations can be used to test several models of particle-nucleus interactions.     

Inclusive production of vector and tensor mesons in antiproton-proton annihilation and non-annihilation interactions at 9.1 GeV/c

Cross sections have been determined for the inclusive production of vector $\text{(?}{}^0\text{, ω,}\text{K}{}^1\text{)}$ and tensor (f, A₂^±) mesons in $\text{p}\text{p}$ reactions at 9.1 GeV/c for both annihilation and non-annihilation processes. Distributions in the Feynman variable x and transverse momentum squared, p_T², have been examined for the ?⁰, ω and f mesons. The slopes for p_T² appear to be exponential and decrease with increasing particle mass for both annihilation and non-annihilation reactions, furthermore the slopes have consistently higher values for non-annihilation reactions. Comparisons with other data indicate that the ratio ?⁰/π^? is independent of antiproton momentum in annihilation processes.     

Γ production from duality and the charge of the new quark

Duality ideas are applied to estimate the upsilon production in e⁺e^? annihilation, hadronic collisions and photoproduction. Simple scaling rules for the cross sections are obtained and compared with experiments. Our results suggest the charge of the new constituent quark is likely to be $\text{?1}\text{3}$.     

Pion production at large transverse momentum

A constituent interchange model is used to give a natural explanation of the observed energy dependence of ISR data for π° production at 90°. It is predicted that at large fixed p_T and sufficiently high energy the cross section will become constant, with a p_T dependence of (p_T²)^?2.5. It is also tentatively suggested that the e⁺e^? annihilation structure function $\text{ν}\text{W}{}_2$ should behave like ω^?1.5 near ω = 0.     

Some information from nucleon-antinucleon annihilation at rest: e+e− annihilation,hadronic fragmentation and deep inelastic structure functions

The experimental spectra of charged pions in $\text{N}\text{N}$ annihilation at rest are described in a model of quasi-two-body decays. The same model predicts the π⁰, ? and ω spectra. We apply a previous calculation to determine in the vector-dominance model, the pions spectra in e⁺e^? annihilation at the same energy. The $\text{N}\text{N}$ system is then used as a heavy hadron in order to describe, in a model-independent way: (i) the projectile fragmentation part in inclusive reactions; (ii) the valence part of the deep inelastic structure function.     

Proton-antiproton annihilations at rest into π0ω, π0η, π0γ, π0π0, and π0η′

Proton-antiproton annihilations at rest in liquid hydrogen were investigated through the inclusive γ spectrum, related to the annihilation. The high-energy part of the spectrum was used to deduce branching ratios for the so far unobserved annihilation channels: $\text{R(}\text{p}\text{p}\text{→π}{}^0\text{ω) = (2.38 ± 0.65)\%}$, $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{η) = (0.82 ± 0.10\%}$, $\text{R}\text{p}\text{p}\text{→π}{}^{\mathrm{0\gamma )}}\text{= (0.015 ± 0.007)\%}$, and $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{π}{}^0\text{= (0.06 ± 0.04)\%}$. An upper limit for the π⁰η^′ channel was deduced to be $\text{R(}\text{p}\text{p}\text{→ π}{}^0\text{η}{}^{\mathrm{\prime }}\text{) < 1.1\%}$.