abstract

We study the existence of smooth, static nontrivial solutions to Einstein–Yang–Mills–Klein–Gordon equations. The absence of static solutions is proven if the Klein–Gordon field is linear and the asymptotic falloff of \(g_{00}\) to unity is quicker than \(1/r\). In the case when \(g_{00}=1+O(\frac {1}{r})\) the system is shown to reduce to the pure gravity, under certain conditions. Possible applications of bifurcation theory for finding solutions which are close to the trivial one in the case when the scalar field is of Higgs type are discussed.

abstract

The experimental analysis of the process of cascading in the target fragmentation region (TFR) is performed on the basis of the available experimental methods and data and the existing phenomenological models. The effect is studied separately for the deuteron and for the heavy nuclei. The following subjects are discussed: 1. the experimental phenomena generated by the existence of the cascading effect in TFR; 2. general features of such process, namely: the effective cascade cross section, the fraction of cascade interactions, multiplicity of particles produced through cascading and their rapidity distributions, the dependence of cascading on energy and on the type of projectile and on the size of the nucleus; 3. the comparison with the phenomenological models and with other proposed mechanisms of particle production in TFR. The possibility of determining the hadronization time (formation time) through the study of the cascading process in TFR is pointed out.

abstract

We calculate spin amplitudes in QED to order \(\alpha ^3\) for the process \(e^+e^- \to \tau ^+\tau ^-(\gamma )\), taking into account effects due to the finite \(\tau \) mass. The Monte Carlo method is used to simulate directly the production and decay of the \(\tau \) leptons. Effects of radiative corrections on the momenta of the decay products are investigated. A quantitative discussion of the correlations induced by the spin in the double \(\tau \) decay is presented. \(Z_0\) exchange is included in the low energy approximation.

abstract

The low \(p_{\rm T}\) results at the SPS colliders are compared with the expectations from conventional theories (Regge–Muller, string models, parton model for sort processes, etc.). Most of the short range order properties of the produced particles, predicted in these theories are badly violated but a few of them are satisfied to a good accuracy. We show that the multi-chain dual parton model allows us to describe the whole picture.

abstract

We discuss the possible applications of Bragg reflection in future detection schemes for low energy (and non-zero mass) cosmic neutrinos based on their coherent interaction with bulk matter. The reflection coefficient for laminated targets is shown to consist of two dominant parts arising from the mean and oscillating components of the target density, and the dependence of each of these terms on both the neutrino and target properties is discussed in detail. The Bragg reflection term provides an enhanced reflectivity for a selected band of neutrino wavelengths, which could be used to increase the detection sensitivity for cosmic neutrinos accelerated into the galaxy by its gravitational potential. For clustered neutrinos, we show that Bragg reflection would not increase the integrated coherent force, but could have experimental advantages in modulating and identifying the neutrino signal.