Physics Letters B 799 (2019) 135014
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Physics Letters B
www.elsevier.com/locate/physletb
Perturbative static quark potential in Maximal Abelian gauge
Matthias Berwein
a,∗
, Yukinari Sumino
b
a
Nishina Center, RIKEN, Wako, Saitama 351-0198, Japan
b
Department of Physics, Tohoku University, 6-3, aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
a r t i c l e i n f o a b s t r a c t
Article history:
Received
4 September 2019
Accepted
7 October 2019
Available
online 10 October 2019
Editor:
J. Hisano
Keywords:
QCD
Static
quark potential
Maximal
Abelian gauge
Perturbation
theory
Renormalization
We calculate the static quark potential for an SU(N) gauge theory in the Maximal Abelian gauge as well as
its Abelian projection up to two loops in perturbation theory. We discuss its renormalization properties.
The result is compared with a recent lattice result at r 0.5fm.
© 2019 The Authors. 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
One of the most interesting features of Quantum Chromody-
namics
(QCD) is its peculiar behavior at low energies, where it
displays confinement. Among the many explanations proposed for
this phenomenon, one of the more interesting approaches utilizes
its similarity to the behavior of a magnetic field in a type II super-
conductor [1].
The magnetic field cannot penetrate the supercon-
ductor
except for narrow flux tubes, much like the chromoelectric
field extends only between confined particles, and if there ex-
isted
elementary magnetic charges, they would be confined inside
a superconductor much like quarks in the vacuum. But whereas a
superconductor forms through the condensation of electrons, there
are no corresponding elementary chromomagnetic charges in QCD.
Instead, it is argued that these are dynamically generated by the
gluon field, and that they exist in a condensed state in the QCD
vacuum.
This
idea has already been extensively studied on the lattice us-
ing
a particular gauge fixing, the so-called Maximal Abelian (MA)
gauge [2], in which chromomagnetic monopoles are topologically
generated. Evidence has been found on the lattice for both the ex-
istence [3]of
these monopoles and their condensation [2]below
a critical temperature. A particularly clear picture emerges from
the study of the static quark potential. The MA gauge treats gluons
*
Corresponding author.
E-mail
addresses: matthias.berwein@riken.jp (M. Berwein),
yukinari.sumino.a4@tohoku.ac.jp (Y. Sumino).
belonging to the maximal Abelian subgroup of SU(N) (i.e., gluons
with diagonal generators) differently from the other gluons, and
the monopoles are all contained in this diagonal part of the gluon
field. Separating the diagonal from the off-diagonal contributions
to the potential, it appears that the linear behavior of the potential
at long distances, which is responsible for confinement, is dis-
played
solely by the diagonal part (in particular by the monopole
contribution), while the off-diagonal part plays a minor role [4]
(or [5]for
a more recent study). In fact, neglecting the off-diagonal
contribution completely does not change the qualitative behavior
of the potential, a feature that is called Abelian dominance. While
it is possible that these phenomena may just be coincidental ar-
tifacts
of the gauge fixing, a common view is that the MA gauge
is particularly convenient in organizing universal features of QCD
that might be obscured in other gauges.
There
is an interesting detail in this result. The linear behavior
of the monopole contribution seems to extend even to short dis-
tances,
where the overall behavior of the potential is Coulombic.
In this region, the potential may be studied in perturbation the-
ory.
Currently, the static potential is computed up to three loops
in perturbative QCD in the Feynman gauge [6] and in the general
covariant gauge [7]. To our knowledge, however, there exists no
perturbative computation of the potential in the MA gauge. In this
paper, in order to expand the picture, we conduct a two-loop cal-
culation
of the potential as well as its Abelian projection in the MA
gauge.
In
section 2 we briefly discuss the particularities of MA gauge
fixing, section 3 then reviews the necessary information on the
static quark potential, while our results are presented in section 4.
https://doi.org/10.1016/j.physletb.2019.135014
0370-2693/
© 2019 The Authors. 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
.