Contact interactions offer a general framework for describing a new interaction with a scale above the energy scale probed. These interactions can occur if the StandardModel particles are composite or if new heavy particles are exchanged. The discovery potential of contact interactions at the LHC in dimuon and dijet final states at startup and the asymptotic reach are presented. PACS. 12.60.Rc ...

Calculations of observables in quantum chromodynamics are typically performed using a method that combines numerical integrations over the momenta of final state particles with analytical integrations over the momenta of virtual particles. I describe the most important steps of a method for performing all of the integrations numerically. Typeset using REVTEX

A solution to the classical field equations in the massless (1+1)-dimensional O(3) sigma model is found, which describes a multi-particle instanton-like transition at high energy. In the limit of small number of initial particles, the number of final particles is shown to be also small, and the probability of the transition is suppressed by exp(−2S 0), where S 0 is the instanton action. This so...

We study an elementary problem of the topological robotics: collective motion of a set of n distinct particles which one has to move from an initial configuration to a final configuration, with the requirement that no collisions occur in the process of motion. The ultimate goal is to construct an algorithm which will perform this task once the initial and the final configurations are given. Thi...