Studies in\bar p p annihilation

Evidence is presented that \(\bar p\) p annihilation proceeds via the formation of two jets, with average transverse momentum of the order of the nucleon mass. The implications of this behaviour is linked to the measured cross sections and multiplicities, and explanations for it have been sought in the underlying gluon and quark constituents of the \(\bar p\) p system. The confrontation of the suggested constituent mechanisms and experimental data lead to the concept that charm meson production may play a significant role in the \(\bar p\) p experiments at the highest available energies.     

Charged-particle multiplicity distribution in 100-GeV/c \bar pd and π− interactions

We present data on \(\bar pn\) and π^? n collisions obtained from an exposure of the 30′' FNAL deuterium filled bubble chamber to a mixed \({{\bar p} \mathord{\left/ {\vphantom {{\bar p} {\pi ^ - }}} \right. \kern-0em} {\pi ^ - }}\) beam with a momentum of 100 GeV/c. We find that in 17±2% of the collisions with the antiproton there is an interaction on the spectator while for the collisions with π^? mesons the corresponding number is 15±2%. The \(\bar pn\) and π^? n multiplicity distributions have average charged multiplicities of 6.46±0.07 and 6.53±0.08 respectively. The average multiplicities for both types of interactions are slightly smaller than those for the corresponding reactions on hydrogen by an amount that is the same as observed at other energies. As an estimate of \(\bar pn\) annihilation we have calculated the difference \(\sigma _n (\bar pn) - \sigma _n (pn)\) for each prong numbern. We find an average multiplicity of 9±1, a value close to that for \(\bar pp\) annihilation at the same energy. combining our data with lower energy \(\bar pn\) annihilation data, we observe that the average negative multiplicity is systematically larger than that for \(\bar pp\) annihilation similar to the difference between neutron and proton target data with other beam projectiles.     

Inclusive ϱ0,K *±(892) andf production in\bar p p Interactions at 12 GeV/c

Inclusive production of ?⁰,K ^*±(892), andf is studied in \(\bar p\) p interactions at 12 GeV/c. The inclusive cross sections for ?⁰,K ^*±(892), andf are found to be 6.7±0.3 mb, 1.0±0.2 mb, and 1.4±0.3 mb, respectively. The differential cross sections are presented as a function of c.m. rapidity, Feynmanx and square of the transverse momentump _T ² . Comparison with the correspondingpp data shows some interesting differences which can be attributed to the \(\bar p\) p annihilation. The results are compared with the predictions of the quark fusion model.     

Rapidity density distributions in antiproton-proton collisions

Data on the density of charged particles in rapidity space for annihilation and non-annihilation p?p interactions at 7.3 and 12 GeV/c are reported. It is shown that the central rapidity density for non-annihilation processes is a simple linear function of $\text{ln}\text{(}\text{s}\text{)}$ from these low energies up to p?p collider energies ($\text{s}\text{=540}\text{GeV}$). Significant differences in density distributions for p?p and e^?e⁺ annihilations at comparable energies are found.     

Estimating functions of canonical correlation coefficients

Let ρ²₁,…,ρ²_p be the squares of the population canonical correlation coefficients from a normal distribution. This paper is concerned with the estimation of the parameters δ₁,…,δ_p, where $\text{δ}{}_{\mathrm{i}}\text{=}\text{ρ}{}^2{}_{\mathrm{i}}\text{(1 ? ρ}{}^2{}_{\mathrm{i}}\text{)}$, i = 1,…,p, in a decision theoretic way. The approach taken is to estimate a parameter matrix Δ whose eigenvalues are δ₁,…,δ_p, given a random matrix F whose eigenvalues have the same distribution as $\text{r}{}^2{}_{\mathrm{i}}\text{(1 ? r}{}^2{}_{\mathrm{i}}\text{)}$, i = 1,…,p, where r₁,…,r_p are the sample canonical correlation coefficients.     

Single-pion production in antiproton-proton interactions

Single-pion production in $\text{p}\text{p}$ interactions at 9.1 GeV/c is analysed and cross sections are given. The p_lab dependence of the isospin amplitudes is determined by a fit to the world data. The data are also compared with the predictions of a reggeized Deck model. The results and the $\text{N}\text{π}\text{N}$ amplitudes are compared with the results at other energies and with the corresponding NπN amplitudes.     

Interference correlations between like pions in the reactionK − p→K − pπ+π+π−π− at 8.25 GeV/c

Zeitschrift für Physik C Particles and Fields - We have observed correlations in the transverse momentum of pion pairs with like and unlike charge produced in 8.25 GeV/cK − p→K...     

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.     

Limits on the impact parameters occuring in specific K−p interactions at 8.25 GeV/c

We have determined a lower limit of the impact parameter for the reactions associated with the channels K^?p → K^?pπ⁺π^?K^?p → λπ⁺π^?π⁰. The limit was found to be highest for the diffractive parts of the first channel (～ 0.52 fm) and smallest for the forward Λ in the second channel (～0.21 fm).We have also examined the elements of the inverse correlation matrix for the transfer: the off-diagonal elements are small (consistent with zero) for n = 4?7 body products. The log 〈Q_i·Q_j〉 of the correlation matrix as a function of $\text{Гi?jГ}$ falls on a straight line and the eigenvalue λ₁ of the transverse momentum transfer eigenfunction was found to increase slightly from ～0.6 for 4-body to ～0.7 for 7-body products. The 〈cosφ_ij〉 of the Q_i, Q_j shows similar behaviour to the 〈Q_i·Q_j〉     

A test of factorisation predictions for the fragmentation processes pp→π± at p momenta of 9.1 and 4.6 GeV/c

Relations have been derived between the invariant cross sections for various inclusive processes by assuming factorisation of the leading (pomeron) and non-leading (meson) trajectories. In this paper predictions for the invariant cross sections $\text{f(}\text{p}\text{p}\text{→π}{}^{\mathrm{\pm }}\text{)(2E}{}^1\text{/π√s)}\text{d}{}^2\text{σ/}\text{d}\text{x}\text{d}\text{p}{}^2{}_{\mathrm{\perp }}{}^2$ have been tested using data from $\text{p}\text{p}$interactions at 4.6 and 9.1 GeV/c.A large discrepancy between experiment and theory is apparent for the π^? data: in the π⁺ case the discrepancy is less marked but still present.