M.R. Setare, H. Adami / Nuclear Physics B 909 (2016) 345–359 347
ing a gravitational Chern–Simons term in [6], and have computed the off-shell potential and
quasi-local conserved charges of some black holes in TMG. We have obtained the quasi-local
conserved charges of Lorentz-diffeomorphism covariant theories of gravity in the first order for-
malism, in paper [26]. But there are theories which are not Lorentz-dif
feomorphism covariant.
In previous paper [27] by introducing the total variation of a quantity due to the infinitesimal
Lorentz-diffeomorphism transformation, we have obtained the conserved charges in the Lorentz-
diffeomorphism non-covariant theories. The proposed formalism in [27] is for on-shell case. As
we have mentioned above, we are going to generalize the proposed formalism to the of
f-shell
case. We try to find an expression for the ADT conserved current which is off-shell conserved
for a given Killing vector field. We generalize off-shell conserved current J
ADT
to make sure
that it is conserved for any diffeomorphism generator ξ . For this purpose, we follow the method
presented in [28] in which the authors took advantage of the metric formalism. J
ADT
is off-shell
conserved if ξ is a Killing vector field. We will show that one can introduce the generalized ADT
current
˜
J
ADT
which is off-shell conserved for an arbitrary diffeomorphism generator ξ . Then,
we can find the generalized ADT conserved charge by virtue of the Poincare lemma, such that
˜
J
ADT
= d
˜
Q
ADT
. We will fix the ambiguity in definition of the generalized ADT conserved cur-
rent by considering the phase space analysis. Then we try to obtain the central extension term,
C(ξ
±
m
, ξ
±
n
), for the algebra of the conserved charges in the context of the CSLTG. We apply our
formalism to the Einstein gravity in the presence of negative cosmological constant, and also
to the GMG. We will find the central charges of dual CFT of the BTZ black hole solutions of
mentioned gra
vity theories. Then by obtaining the eigenvalues of the Virasoro generators, l
±
n
,
and using the Cardy formula we will obtain the Bekenstein–Hawking entropy of the BTZ black
hole, as well as the energy and the angular-momentum of the BTZ solution of GMG. By using
the Killing vectors corresponding to the mentioned quantities we will obtain energy, angular-
momentum and entropy of the BTZ black hole solution of GMG ag
ain which exactly coincide
with previous results.
2. Generalized conserved current
In this section, we are going to find an off-shell conserved current and corresponding con-
served charge of the Chern–Simons-like theories of gravity. We generalize this conserved current
so that it corresponds to an arbitrary diffeomorphism rather than a diffeomorphism which is gen-
erated by a Killing vector field.
The Lagrangian 3-form of the Chern–Simons-lik
e theories of gravity (CSLTG) is given
by [24]
L =
1
2
g
rs
a
r
· da
s
+
1
6
f
rst
a
r
· a
s
× a
t
. (1)
In the above Lagrangian a
ra
= a
ra
μ
dx
μ
are Lorentz vector valued one-forms where, r =
1, ..., N and a indices refer to flavor and Lorentz indices, respectively. We should mention
that, here, the wedge products of Lorentz-vector valued one-form fields are implicit. Also, g
rs
is
a symmetric constant metric on the flavor space and f
rst
is a totally symmetric “flavor tensor”,
which are interpreted as the coupling constants. We use a 3D-vector algebra notation for Lorentz
codimension-two surface. As can be seen in Eq. (22), J
ADT
is conserved current when ξ is a Killing vector field in any
point of space-time. In this case δ
ξ
a
r
= δ
ξ
E
r
= 0, so dJ
ADT
= 0.