High-energy Nucleon-nucleon Collisions Research Articles

Heavy-quark hadroproduction in k T -factorization approach with unintegrated gluon distributions

We consider the processes of heavy-quark production using the unintegrated gluon distributions. The numerical predictions for high-energy nucleon-nucleon and photon-nucleon collisions of the k T -factorization approach (semihard theory) are compared with the experimental data from the Tevatron collider and HERA. The total production cross sections and pT distributions are considered and they are in reasonable agreement with the data for reasonable values of QCD scale.

Multi-quark effects in high energy nucleon-nucleon and nucleus-nucleus collisions

Recent data obtained in two experiments performed in the framework of the Bucharest-Dubna collaboration are presented i.e.: the observation of narrow dibaryonic resonances in neutron-proton interactions in 1m HBC at different momenta of incident neutrons in the range 1–5 GeV/c, and the cumulative production of negative pions in nucleus-nucleus interactions in SKM-200 streamer chamber at 4.5 GeV/c. The interpretation of these results in terms of multiquark states is discussed.

Inclusive production of hadrons in nucleus-nucleus collisions at high energies

A simple model for inelastic nucleus-nucleus collisions at high energies is proposed. Predictions are summarized in approximate, but simple, scaling laws that directly relate hadron production in high-energy nucleus-nucleus collisions to hadron production in high-energy nucleon-nucleon collisions. The possible use of nucleus-nucleus collisions to investigate future energy domains of particle physics with present accelerators is emphasized.

Elastic Scattering, Production Process and Their Relation in High Energy Nucleon-Nucleon Collisions

Elastic Scattering, Production Process and Their Relation in High Energy Nucleon-Nucleon Collisions

Elastic Scattering, Production Process and Their Relation in High Energy Nucleon-Nucleon Collisions

Elastic Scattering, Production Process and Their Relation in High Energy Nucleon-Nucleon Collisions

Unitary eikonal formalism for multiproduction at high energy

Unitary models for meson production in high energy nucleon-nucleon collisions are discussed in the approximation that all transverse momenta are small and that the centre-of-mass energy carried off by the produced secondaries is also small compared to the incoming nucleon momenta. Spin and isospin effects are neglected. It is shown that if the number of modes in which the mesons are produced is finite and if the requirement of crossing symmetry in the meson variables is properly taken into account, then it is possible to derive a general closed explicit expression for the S-matrix elements for all models of this kind.

Consequences of “Scaling” for High Energy Cosmic Rays

FEYNMAN1 has recently suggested that the energy spectrum of particles emitted in high energy nucleon-nucleon collisions may “scale” with increasing energy in a rather simple way. The suggestion is based on the parton model of the nucleon and at least some of the predictions seem to fit accelerator and cosmic-ray data2–4.

Production in the W-boson in nucleon-nucleon collisions

The cross section for the production of the intermediate vector boson in high-energy nucleon-nucleon collisions is estimated in some of the models proposed for the description of highly inelastic processes. An expression for the total cross section is obtained, which is a smooth function of the c.m. energy and the mass of the W-boson.

Radiation-Type Eikonal Model for Uncorrelated Meson Production in High-Energy Nucleon-Nucleon Collisions

A model for uncorrelated meson production in high-energy nucleon-nucleon collisions is proposed, using the eikonal formalism to extract a specific form for the optical potential from nucleon-nucleon elastic scattering data. This potential is used to form the eikonal wave function of the scattering system, from which is constructed a model source density for radiated pions. The normalization is derived from Adler's formulation of the soft-pion limit. Predictions involving no free parameters are compared with pion spectra from $\mathrm{pp}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}+\mathrm{anything}$ at 12.2, 19.2, and 30 GeV/c. Good to reasonable agreement is obtained for c.m. emission angles less than 20\ifmmode^\circ\else\textdegree\fi{}. The mean multiplicity for charged pions is also found to agree qualitatively with experiment. A covariant formulation of the model, using the Bethe-Salpeter equation, is proposed, but no calculations are presented.

Production of nucleon isobars in high energy nucleon-nucleon collisions

Assuming predominance of elastic and quasi-elastic isobar production processes in high energy nucleon-nucleon collisions, N + N → N + N, N + N ∗, N ∗ + N ∗ , and using experimental information on the elastic scattering as the input, differential cross sections of the isobar production are worked out on the basis of unitarity and time reversal invariance together with certain simplifying kinematical assumptions. The isobars will be, on the average, more collimated than the elastically scattered nucleons; their angular distribution will possibly show a very sharp peak followed by a rather flat tail.

Analysis of angular distribution of secondary particles in ultra high energy nucleon-nucleon collisions

Starting from the exact expression for a transition probability in the relativistic angular momentum representation and using some approximations following from the assumed peripherality of collisions we have obtained an expression for the angular distribution of secondary particles. The differential and integral angular distributions calculated for the energies 10 3 GeV, 10 4 GeV, 10 5 GeV, lead to a natural explanation of the appearance of two maxima in the angular distributions.

Energy-momentum transfers in high-energy nuclear collisions

It is pointed out that the form of the distribution of energy-momentum transfers in the « diffraction region » of high-energy elastic proton-proton and pion-nucleon scattering is applicable to the « longitudinal » energy-momentum transfers in high-energy (~< 1012 eV) inelastic nucleon-nucleon collisions. Except for a change in the value of a parameter of the distribution, the same is also applicable to the momentumtransfer distribution in the collision of the virtual particles into which the nucleon-nucleon collisions can be decomposed on the basis of an assumed model. The implication of applying these energy-momentumtransfer distributions to the case of pion-nucleon collisions is examined briefly.

Range of Very High-Energy Nucleon-Nucleon Collisions

Range of Very High-Energy Nucleon-Nucleon Collisions

Semi-Phenomenological Model for Meson Production in High-Energy Nucleon-Nucleon Collisions

A two-center model is proposed for the description of meson production in high-energy nucleon-nucleon collisions. In this model the effect of one nucleon on the other is replaced by an equivalent interaction which frees pions bound in the second nucleon. The model takes into account peripheral collisions only and does not include mesons emanating from core-core collisions. A transverse momentum (${p}_{T}$) distribution is obtained as a function of only the impact parameter and core radius. Our distributions agree well with experiment, the most probable ${p}_{T}$ being 0.3-0.4 BeV/c. The angular distribution obtained does not deviate much from an isotropic distribution in the center-of-mass system of the emitting nucleon.

One-pion exchange model in high energy nucleon-nucleon collisions

The one pion exchange model is applied to the investigation of inelastic proton-nucleon interactions with a primary kinetic energy of 8·3 GeV. The experimental comparison is carried out using a modified momentum-energy four-vector of the virtual pion,\(\bar \Delta \), which is determined from the energy and angle of emission of the recoil nucleon. It is shown that the OPE model — if we include the pion-nucleon resonance (T=3/2) effects — may describe the basic mechanism of peripheral interactions for\(\bar \Delta ^2 \)<0·2 ≈ (3μ)2.

On mesic Čerenkov radiation

With the help of the Klein-Gordon equation a modification is presented of the model of multiple meson-production in high-energy nucleon-nucleon collisions, proposed by Czyż, Ericson and Glashow.

Statistical weights of many-particle systems in spin or isospin space

A theory is developed for high-energy nucleon-nucleon collisions, where the end-particles have to combine to yield states of given total isospin and charge. Charge distribution coefficients P/sup J/ were determined for systems composed of spin 1/2, 1, and 3/2 and all possible combinations of m's. These determined coefficients are given in tabular form for the prescribed conditions for use in statistical theories of meson production. Two checks are described for the accuracy of the tables. Both stem from the fact that the recoupling transformation is orthogonal. (B.O.G.)

On the two fluid model in multiple production of mesons

The mechanism of multiple particle production in high energy nucleon-nucleon collisions is investigated using the two fluid model. The theoretical inelasticity is numerically calculated.

A new model for multiple meson production at high energies

A new approach to the multiple meson production processs is proposed, which is based upon the peripheral nature and energy-independent behaviour of high-energy nucleon-nucleon collisions. A specific model suggested by the analogy with Čerenkov radiation is described.

Production Spectrum of Mesons in High-Energy Nucleon-Nucleon Collisions

In order to obtain a production spectrum of mesons in the center-of-mass system, three high-energy nuclear collisions were selected which satisfy very stringent criteria for nucleon-nucleon collisions and for which the momenta of all charged particles could be measured in the laboratory system. The results show that more than one-half of the mesons have energies less than 1 Bev in the center-of-mass system. Only a few particles emitted under very small angles in the forward and backward direction have higher energies, extending up to 10 Bev. The low-energy end of the spectrum is compared with results obtained in experiments with the Berkeley Bevatron.