abstract

The radiation reaction force is found for a one-parameter class of coordinate systems which generalize the harmonic coordinates. It is shown that there exists a coordinate system in which the radiation reaction force vanishes.

abstract

In this paper the explicit form of the components of the gravitational superenergy tensor, \(_{\rm g}S\), for the Einstein–Rosen gravitational wave is given.

abstract

We present a Monte Carlo calculation for multiparticle events in \(e^+e^-\) annihilation. The underlying model is a chain decay model and has the following features: (i) Baryon production as well as meson production, (ii) Energy-momentum conservation, (iii) Conservation of quantum numbers like \(Q\), \(I_3\), \(S\), \(B\), (iv) Inclusion of transverse momentum of the emitted hadrons, (v) Fragmentation via meson and baryon resonances of the lowest SU(3) multiplets. We compare the results of the model with experimental data on \(e^+e^-\) annihilation including average multiplicities of charged and neutral particles, longitudinal and transverse momentum distributions of the final hadrons and distributions of jet variables like Thrust. In general the agreement of the model with experimental data is good.

abstract

The high energy behavior (in the Regge limit) of nonabelian gauge theories is reviewed. After a general remark concerning the question to what extent the Regge limit can be approached within perturbation theory, we first review the reggeization of elementary particles within nonabelian gauge theories. Then the derivation of a unitary high energy description of a massive (= spontaneously broken) nonabelian gauge model is described, which results in a complete reggeon calculus. There is strong evidence that the zero mass limit of this reggeon calculus exists, thus giving rise to the hope that the Regge behavior in pure Yang–Mills theories (QCD) can be reached in this way. In the final part of these lectures two possible strategies for solving this reggeon calculus (both for the massive and the massless case) are outlined. One of them leads to a geometrical picture in which the distribution of the wee partons obeys a diffusion law. The other one makes contact with reggeon field theory and predicts that QCD in the high energy limit is described by critical reggeon field theory.

abstract

A ratio of the relativistic secondary multiplicities for hadron-nucleus and hadron–nucleon interactions, \(R_{\rm s}\)(hA), is considered in the central region and a part of the target nucleus fragmentation region. The multiplicities arc obtained from the experimental average numbers of relativistic charged or negative particles by subtraction of the projectile fragment numbers estimated theoretically. Two hypotheses on the \(A\) dependence of the secondary multiplicity in a constituent quark interaction with a nucleus are discussed. An assumption that this multiplicity is independent of \(A\) leads to \(R_{\rm s}\)(hA) = \(\bar v_{\rm hA}/\bar v_{\rm qA}\). An alternative assumption that the qA multiplicity increases with \(A\) due to quark rescattering from several nucleons gives \(R_{\rm s}\)(hA)= \(\bar v_{\rm hA}\). Comparison with experiment in the former case requires a great number of positively charged badrons, probably protons, emitted from the nucleus. This number must rise significantly with both \(A\) and incident energy. The latter hypothesis is consistent with all data on \(\left \lt n_{\rm s}\right \gt \) as well as \(\left \lt n_-\right \gt \) in pA collisions but disagrees by \(\approx 20\)% with \(\left \lt n_-\right \gt \) in \(\pi ^-\)A interactions.