6 research outputs found
A class of the NSVZ renormalization schemes for SQED
For the supersymmetric electrodynamics we investigate
renormalization schemes in which the NSVZ equation relating the
-function to the anomalous dimension of the matter superfields is valid
in all loops. We demonstrate that there is an infinite set of such schemes.
They are related by finite renormalizations which form a group and are
parameterized by one finite function and one arbitrary constant. This implies
that the NSVZ -function remains unbroken if the finite renormalization
of the coupling constant is related to the finite renormalization of the matter
superfields by a special equation derived in this paper. The arbitrary constant
corresponds to the arbitrariness of choosing the renormalization point. The
results are illustrated by explicit calculations in the three-loop
approximation.Comment: 12 page
The -scheme QCD contributions to the Adler function and Bjorken polarized sum rule in the Crewther-type two-fold -expanded representation
We consider the two-fold expansion in powers of the conformal anomaly and of
the strong coupling for the non-singlet contributions to Adler
-function and Bjorken polarized sum rule calculated previously in the
\MSbar-scheme at the four-loop level. This representation provides relations
between definite terms of different loop orders appearing within the
-expansion of these quantities. Supposing the validity of this
two-fold representation at the five-loop order and using these relations, we
obtain some corrections to the -function, to the
-ratio of -annihilation into hadrons and to Bjorken polarized sum
rule. These corrections are presented both analytically in the case of the
generic simple gauge group and numerically for the color group. The
arguments in the favor of validity of the two-fold representation are given at
least at the four-loop level. Within the -expansion procedure the
analytical Riemann -contributions to the five-loop expressions for the
Adler function and Bjorken polarized sum rule are also fixed for the case of
the generic simple gauge group.Comment: 30 pages, 1 Figure, 6 Tables, text modified, the results unchanged,
list of references modified, accepted for publication in JHE