1301.7510 (Bo Feng et al.)

Analytic structure of one-loop coefficients    [PDF]

Bo Feng, Honghui Wang

By the unitarity cut method, analytic expressions of one-loop coefficients have been given in spinor forms. In this paper, we present one-loop coefficients of various bases in Lorentz-invariant contraction forms of external momenta. Using these forms, the analytic structure of these coefficients becomes manifest. Although singularities can be divided into the first-type and the second-type, coefficients contain only second-type singularities while the first-type singularities are given by scalar bases. We find that for general situations, coefficients of a given basis contains not only second-type singularity intrinsically related to the topology of the basis, but also those second-type singularities intrinsically related to the mother topologies of the given basis.

View original: http://arxiv.org/abs/1301.7510