Structure of three-loop contributions to the
β-function of
SQED with
Nf flavors, regularized by the dimensional reduction
S. S. Aleshin+, A. L. Kataev*, K. V. Stepanyantz+
+Physical Faculty Lomonosov MSU, Department of Theoretical Physics, 119991 Moscow, Russia
*Institute for Nuclear Research of the RAS, 117312 Moscow, Russia
Abstract
In the case of using the higher derivative
regularization for N=1 supersymmetric quantum electro-dynamics (SQED) with
Nf flavors the loop integrals giving the β-function are integrals of
double total derivatives in the momentum space. This feature allows to reduce
one of the loop integrals to an integral of the δ-function and to
derive the NSVZ relation for the renormalization group functions defined in
terms of the bare coupling constant. In this paper we consider N=1 SQED
with Nf flavors regularized by the dimensional reduction in the
-scheme. Evaluating the scheme-dependent three-loop
contribution to the β-function proportional to (Nf)2 we find the
structures analogous to integrals of the δ-singularities. After adding
the scheme-independent terms proportional to (Nf)1 we obtain the known
result for the three-loop β-function.