Physics Letters B 730 (2014) 184–189
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Physics Letters B
www.elsevier.com/locate/physletb
Scheme independent consequence of the NSVZ relation for N = 1
SQED with N
f
flavors
A.L. Kataev
a
, K.V. Stepanyantz
b,∗
a
Institute for Nuclear Research of the Russian Academy of Science, 117312, Moscow, Russia
b
Moscow State University, Physical Faculty, Department of Theoretical Physics, 119991, Moscow, Russia
article i nfo abstract
Article history:
Received 22 November 2013
Received in revised form 9 January 2014
Accepted 27 January 2014
Available online 30 January 2014
Editor: L. Alvarez-Gaumé
Keywords:
Higher covariant derivative regularization
Supersymmetry
β-Function
Subtraction scheme
The exact NSVZ β-function is obtained for N = 1SQEDwith N
f
flavors in all orders of the perturbation
theory, if the renormalization group functions are defined in terms of the bare coupling constant and
the theory is regularized by higher derivatives. However, if the renormalization group functions are
defined in terms of the renormalized coupling constant, the NSVZ relation between the β-function and
the anomalous dimension of the matter superfields is valid only in a certain (NSVZ) scheme. We prove
that for N = 1SQEDwith N
f
flavors the NSVZ relation is valid for the terms proportional to (N
f
)
1
in an
arbitrary subtraction scheme, while the terms proportional to (N
f
)
k
with k 2 are scheme dependent.
These results are verified by an explicit calculation of a three-loop β-function and a two-loop anomalous
dimension made with the higher derivative regularization in the NSVZ and MOM subtraction schemes. In
this approximation it is verified that in the MOM subtraction scheme the renormalization group functions
obtained with the higher derivative regularization and with the dimensional reduction coincide.
© 2014 The Authors. Published by Elsevier B.V. Open access under CC BY license.
Funded by SCOAP
3
.
1. Introduction
The β-function of N = 1 supersymmetric gauge theories is re-
lated with the anomalous dimension of the matter superfields.
This relation, derived in Refs. [1–3], is usually called “the exact
Novikov, Shifman, Vainshtein, and Zakharov (NSVZ) β-function”.
For the N = 1 supersymmetric Yang–Mills theory without matter
superfields the NSVZ β-function was obtained in Refs. [1,4].Inthe
case of the N = 1 supersymmetric electrodynamics (SQED) with
N
f
flavors, which is considered in this Letter, the NSVZ β-function
has the following form [5,6]:
β(α
0
) =
α
2
0
N
f
π
1 − γ (α
0
)
. (1)
This relation, derived from general arguments, can be verified by
explicit calculations. Usually for calculating quantum corrections
SUSY theories are regularized by the dimensional reduction (DRED)
[7] supplemented by the DR-scheme. However, DRED is not math-
ematically consistent [8]. As a consequence, supersymmetry can be
broken by quantum corrections in higher loops [9–11].
Explicit calculations made in the DR-scheme in the one- [12]
and two-loop [13] approximations agree with the NSVZ β-function,
because a two-loop β-function and a one-loop anomalous di-
*
Corresponding author.
mension are scheme independent in theories with a single cou-
pling constant. In higher orders [14–19] the exact NSVZ relation
for the renormalization group (RG) functions defined in terms
of the renormalized coupling constant can be obtained with the
DR-scheme after an additional finite renormalization. This finite
renormalization should be fixed in each order of the perturba-
tion theory, starting from the three-loop approximation. However,
at present, there are no general prescriptions, how one should
construct this finite renormalization using the DR-scheme in all
orders.
In the Abelian case the NSVZ β-function can be obtained in
all orders using the Slavnov higher derivative (HD) regularization
[20,21]. This regularization is mathematically consistent and can
be formulated in an explicitly supersymmetric way [22,23].The
HD regularization allows to obtain the NSVZ β-function for the
RG functions defined in terms of the bare coupling constant [24,
25]. The reason for this is that the integrals needed for obtaining
such a β-function in SUSY theories are integrals of total derivatives
[26–28] and even double total derivatives [29–32]. As a conse-
quence, one of the loop integrals can be calculated analytically, and
a β-function in an L-loop approximation can be related with an
anomalous dimension of the matter superfields in the (L − 1)-loop
approximation [24]. However, if the RG functions are defined in
terms of the renormalized coupling constant, the NSVZ β-function
is obtained only in a special subtraction scheme. This scheme was
constructed in [25] by imposing the boundary conditions
http://dx.doi.org/10.1016/j.physletb.2014.01.053
0370-2693 © 2014 The Authors. Published by Elsevier B.V. Open access under CC BY license. Funded by SCOAP
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