Hadronic Bremsstrahlung Research Articles

Diffractive and nondiffractive mechanisms and the universality of multiplicity distributions

Using the universality of multiplicity distributions as a guide we motivate a simple physical picture for the multiparticle structure of both diffractive and nondiffractive regimes. We assume that hadronic bremsstrahlung is the common underlying mechanism.

Grand partition function of hadronic bremsstrahlung

The grand partition function of hadronic bremsstrahlung is obtained using saddle-point procedures. Several levels of approximation are considered. The results are qualitatively consistent with earlier simple approximations.

High-energy collisions and the breakdown of the usual conditions of unitarity and causality

We discuss the questions of unitarity and causality in the ordinary and charge-conserving hadronic bremsstrahlung models, which describe quasielastic collisions of two primary particles with the emission of secondary charged pions. While the ordinary hadronic bremsstrahlung model satisfies the usual conditions of unitarity and causality, the charge-conserving hadronic bremsstrahlung model does not. The newly formulated production unitarity (which takes into account the fact that the secondary pions never occur in the initial state) is satisifed by both models. A new notion of the production causality (which seems to be a natural causality property of hadronic bremsstrahlung models) is found to be formally satisfied by both models. In view of the fact that the charge-conserving hadronic bremsstrahlung model gives a good description of the gross features of particle production whereas the ordinary model does not, we suggest that some causality requirements may in general pose overly stringent conditions on theories describing physical phenomena.

Generalized hadronic bremsstrahlung model and two regimes in high energy collisions

The existence of lower and higher regimes in high energy multiparticle reactions has been argued recently by Bialas and Zalewski (see abstr. A49592 of 1972) and independently by Berger and Krzywicki (see abstr. A75282 of 1971). In each of the energy regimes, quantities like the average multiplicity and the correlation parameters should show markedly different behaviour. Within the framework of the generalized hadronic bremsstrahlung model (in which charge conservation is incorporated) the authors, on the one hand, reinforce the notion of two energy regimes as specifically suggested by Bialas and Zalewski, while, on the other hand, they show that the small-scale oscillations in high energy proton-proton scattering might be considered as one of the characteristics of the higher energy regime.

Production of large-transverse-momentum mesons from a meson beam

The Landshoff-Polkinghorne quark-fusion model for the production of large-transverse-momentum mesons from high-energy hadronic processes is applied to meson-nucleon collisions. A second, leading-particle, contribution from large-angle scattering of the incident meson is included in the calculation and has the same power dependence on ${p}_{T}$ at fixed $\frac{{p}_{T}}{\sqrt{s}}$ and fixed center-of-mass scattering angle. Numerical calculations are presented for ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}M+X$ assuming SU(3) couplings of quarks to the pseudoscalar mesons $M$. Mainly because of the leading-particle effect, some of the cross sections are substantially higher than in proton-proton collisions. Although the over-all normalization is obtained by fitting just the quark-fusion model to the experimental data on $\mathrm{pp}\ensuremath{\rightarrow}\ensuremath{\pi}+X$ at large ${p}_{T}$, it is estimated that the choice of normalization is not substantially changed by the inclusion in this fit of the hadronic bremsstrahlung process proposed by Blandkenbecler, Brodsky, and Gunion.

Physical effects of hadronic bremsstrahlung: Reactions at large and small momentum transfers

The synthesis of Regge behavior and other hadronic features with the parton model is discussed. Regge behavior of electromagnetic and weak amplitudes is shown to be a consequence of hadronic bremsstrahlung and the Regge behavior of hadronic amplitudes. A characterization of the hadronic wave function in terms of two components is emphasized. One component, which arises from the constituents of the hadronic bremsstrahlung, yields the wee-parton spectrum and Regge behavior and falls rapidly as any one constituent is constrained to take most of the momentum of the incident hadron. The second component, which is hadron irreducible, and most probably involves the minimum number of parton constituents, must have approximately power-law falloff in invariant variables. Only this second component contributes to large-angle exclusive scattering, the form factors at large $t$, and the scaling structure function for $x$ near 1. This component is responsible for the Drell-Yan-West relation and yields simple crossing to the annihilation channel at $x\ensuremath{\sim}1$. Our approach and analysis clarify the nature of the impulse approximation in hadronic scattering. For example, the dramatic fixed-pole nature of the Compton amplitude at large $t$ is discussed and its importance is emphasized.

Bremsstrahlung model for hadron production at large transverse momentum

A hadronic bremsstrahlung model is presented which provides an understanding of several of the recently observed phenomena at large transverse momenta.

Large momentum transfer reactions, without partons

Three recent experiments involving large 4-momentum transfer are compared to predictions of the hadronic bremsstrahlung model, witho t partons.

Tests of Hadronic Bremsstrahlung Production at Large Nucleon Momentum Transfer

It is suggested that hadronic bremsstrahlung may become the dominant production process in nucleon-nucleon reactions at large momentum transfer to the final nucleons. Correlation tests are proposed to distinguish the model from other models of inclusive processes.

Inclusive processes at high transverse momentum

The interchange theory for inclusive scattering at large transverse momentum is extended into kinematic regions where Regge effects are important. Hadronic bremsstrahlung is shown to lead inevitably to Reggeization of the fundamental production process as s goes to infinity for fixed, large, P T. The cross sections are shown to rise to their ultimate scaling limit. This transition zone connects smoothly with the Feynman scaling region at low p T, and the deep scale-invariant region at large p T ∼ O(√ s). The inclusive results of the interchange theory have the form of the standard fragmentation, triple Regge, and pionization formulae in their respective regions, but in addition predict the behavior of the associated residues and trajectories at large t or p 2 T.