Tuesday, February 21, 2012

1202.4303 (J. Blümlein et al.)

Evaluation of Multi-Sums for Large Scale Problems    [PDF]

J. Blümlein, A. Hasselhuhn, C. Schneider
A big class of Feynman integrals, in particular, the coefficients of their
Laurent series expansion w.r.t.\ the dimension parameter $\ep$ can be
transformed to multi-sums over hypergeometric terms and harmonic sums. In this
article, we present a general summation method based on difference fields that
simplifies these multi--sums by transforming them from inside to outside to
representations in terms of indefinite nested sums and products. In particular,
we present techniques that assist in the task to simplify huge expressions of
such multi-sums in a completely automatic fashion. The ideas are illustrated on
new calculations coming from 3-loop topologies of gluonic massive operator
matrix elements containing two fermion lines, which contribute to the
transition matrix elements in the variable flavor scheme.
View original: http://arxiv.org/abs/1202.4303

No comments:

Post a Comment