Physics Letters B 772 (2017) 294–299
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Renormalization group: New relations between the parameters of the
Standard Model
S. Rebeca Juárez W.
a
, Piotr Kielanowski
b,∗
, Gerardo Mora
c
, Arno Bohm
d
a
Departamento de Física, Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, U.P . “Adolfo López Mateos”, C.P. 07738, Ciudad de México,
Mexico
b
Departamento de Física, Centro de Investigación y de Estudios Avanzados, C.P. 07000, Ciudad de México, Mexico
c
División Académica de Ciencias Básicas, Universidad “Juárez” Autónoma de Tabasco, Mexico
d
Department of Physics, University of Texas at Austin, USA
a r t i c l e i n f o a b s t r a c t
Article history:
Received
29 March 2017
Received
in revised form 13 June 2017
Accepted
22 June 2017
Available
online 27 June 2017
Editor:
A. Ringwald
Keywords:
Renormalization
group
Standard
Model
We analyze the renormalization group equations for the Standard Model at the one and two loops levels.
At one loop level we find an exact constant of evolution built from the product of the quark masses and
the gauge couplings g
1
and g
3
of the U (1) and SU(3) groups. For leptons at one loop level we find that
the ratio of the charged lepton mass and the power of g
1
varies 4 ×10
−5
in the whole energy range. At
the two loop level we have found two relations between the quark masses and the gauge couplings that
vary 4% and 1%, respectively. For leptons at the two loop level we have derived a relation between
the charged lepton mass and the gauge couplings g
1
and g
2
that varies 0.1%. This analysis significantly
simplifies the picture of the renormalization group evolution of the Standard Model and establishes new
important relations between its parameters. There is also included a discussion of the gauge invariance
of our relations and its possible relation to the reduction of couplings method.
© 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
1. Introduction
In particle physics the renormalization group is used for the
study of the asymptotic properties of the theory [1,2]. The renor-
malization
group equations (RGE) for the Standard Model [3–14]
is
a set of coupled nonlinear differential equations, derived pertur-
batively,
for the parameters of the theory (couplings and masses).
The full set of RGE for the Standard Model is known up to two
loops [15] and some partial results are known at higher orders
(see [16] and references therein). There are no known exact solu-
tions
of the full set of RGE for the Standard Model and only some
partial results were obtained. At one loop, equations for the gauge
couplings decouple and are solved exactly, but at two loops this
is not the case. Another approach, is to use the hierarchy of the
parameters of the Standard model, keeping only certain powers of
the quark and lepton masses and of λ
CKM
≈ 0.21 of the Cabibbo–
Kobayashi–Maskawa
(CKM) matrix [17]. In such a way one obtains
the exact solutions of the approximate equations [18]. The most
*
Corresponding author.
E-mail
addresses: rebeca@esfm.ipn.mx (S.R. Juárez W.), kiel@fis.cinvestav.mx
(P. Kielanowski),
gerardo.mora@ujat.mx (G. Mora), bohm@physics.utexas.edu
(A. Bohm).
precise analysis of the renormalization group evolution of the Stan-
dard
Model is done by numerical methods, which give very precise
predictions for the evolution of the couplings, masses and CKM
matrix parameters.
The
aim of this paper is to find relations between the param-
eters
of the Standard Model that remain constant (or are slowly
varying) during the renormalization group evolution. We start with
one loop equation and find an exact constant for the quark masses
and gauge couplings. Next we consider a lepton sector and find
that with great accuracy (∼ 4 × 10
−5
) the charged lepton masses
flow proportionally to the g
−18/41
1
. For the two loop case we find
two generalizations of the one loop constant for quarks and one
for leptons.
The
study of the renormalization group invariants in the
Standard Model and its extensions has been done before, see
e.g., Ref. [19] (and references therein), where such invariants were
studied for the minimal supersymmetric extension of the Standard
Model. The invariants in the lepton sector were analyzed in [20]. In
Ref. [21] an approximation of two flavors was used to simplify the
problem of the analysis of complicated non-linear equations. Re-
cently,
such invariants were analyzed within the powerful scheme
of the flavor invariants in the minimal flavor violating extension of
the Standard Model [22,23]. One should notice that all these at-
tempts
have been limited to the one loop renormalization group
http://dx.doi.org/10.1016/j.physletb.2017.06.059
0370-2693/
© 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.