Real and Image Fields of a Relativistic Bunch

We derive analytical expressions for external fields of a charged relativistic bunch with a circular cross section. At distances far from the bunch, the field reduces to the relativistic modified Coulomb form and in the near region, reproduce the external fields of a continuous beam. If the bunch is surrounded by conducting surfaces, the bunch self-fields are modified. Image fields generated by a bunch between two parallel conducting planes are studied in detail. Exact summation of image fields by the direct method invented by Laslett allows the infinite series to be represented in terms of elementary trigonometric functions.Comment: 10 page

Kinematic selection criteria in a new resonance searches: Application to pentaquark states

In this note I recall some features of two-body decay kinematics which can be effectively applied, in particular, in experimental searches for pentaquark states.Comment: 11 pages, 5 figures, 1 tabl

Prompt photon, Drell-Yan and Bethe-Heitler processes in hard photoproduction

We present prospects and requirements for the study at HERA of hard photon processes which generate high $p_T$ photons in the final state, and processes which generate Drell-Yan lepton pairs.Comment: 6 pages, 3 embedded figures. To appear in the proceedings of the workshop "Future physics at HERA