abstract

The total cross-section for the Drell–Yan process is calculated with the hadron mass corrections included. We show that these corrections are important for the collision energy less than 10 GeV and they become negligible for higher energies.

abstract

In an optical model in which heavy-flavour production is described as coherent scattering within the nucleon, the total heavy-flavour cross-section is expected to obey a \(m_{\rm q}^{-2}\) dependence, whilst the partial differential cross-section \(d\sigma /dp_{\rm T}\) for top hadrons is expected to show a broad plateau above \(\sim 20\) GeV/\(c\) in transverse momentum. The expected top hadron signal \(d\sigma /dp_{\rm T}\) is 60 nb for \(m_{\rm t}=20\) GeV/\(c^2\) appearing in the angular range \(\langle \theta \rangle \approx 10^{\circ }\) –\(20^{\circ }\).

abstract

We reexamine the O(\(\alpha ^3\)) corrections to the process e\(^+\)e\(^-\to \tau ^+\tau ^-\) (or any other heavy fermion pair) taking into account the effects of the masses of the final-state particles. The relevant analytic formulae are presented as well as some Monte Carlo results.

abstract

Solutions to the Yang–Mills equations being infinite 1/g power series are investigated. An explicit example of non-Abelian solution of such a type is given. In the strong coupling limit it tends to the coupling constant independent solution which have been found recently.

abstract

We describe how the unification of gauge interactions with gravitational interactions can be obtained from pure higher dimensional gravity. The possibility of such a theory having some predictive power for the low-energy parameters is discussed.

abstract

The width \({\mit \Gamma }_{\rm NM}(\varrho , k_{\mit \Sigma }\)) of the state of \({\mit \Sigma }\) hyperon moving with momentum \(k_{\mit \Sigma }\) in nuclear matter of density \(\varrho \) is expressed through the \({\mit \Sigma }N\) scattering cross sections. Exclusion principle and dispersive effects are taken into account. Results obtained for \({\mit \Gamma }_{\rm NM}(\varrho , k_{\mit \Sigma }\)) are used in estimating the width of \({\mit \Sigma }\) bound states in \({\mit \Sigma }\) hypernuclei and in \({\mit \Sigma }\) atoms, and the absorptive potential for \({\mit \Sigma }\)-nucleus scattering.