Kinematics of t-channel and Photon Radiation Processes in carlomat

Abstract

The automatic generation of multichannel Monte Carlo phase-space integration routines of carlomat, which up to now took into account only mappings of ∼ 1∕s or Breit–Wigner behaviour of the s-channel diagrams, is being supplemented with the parameterizations which map away the t-channel, soft and collinear photon or gluon emission. In order to improve numerical stability, the quadruple precision versions of the routines for computation of the helicity amplitudes and phase-space parameterizations have been written and calls to them are being implemented in the code generation part of the program.