A Complex One-Loop LIbrary with Extended Regularizations

Features of the library

COLLIER is a fortran library for the numerical evaluation of one-loop scalar and tensor integrals appearing in perturbative relativistic quantum field theory with the following features:

   scalar and tensor integrals for high particle multiplicities

   dimensional regularization for ultraviolet divergences

   dimensional regularization for soft infrared divergences
      (mass regularization for abelian soft divergences is supported as well)

   dimensional regularization or mass regularization for collinear mass singularities

   complex internal masses (for unstable particles) fully supported
      (external momenta and virtualities are expected to be real)

   numerically dangerous regions (small Gram or other kinematical determinants)
      cured by dedicated expansions

   two independent implementations of all basic building blocks allow for internal cross-checks

   cache system to speed up calculations