Eur. Phys. J. C (2020) 80:292 Page 5 of 26 292
In accordance with our previous works on higher-order cor-
rections to the NMSSM Higgs boson masses [26–29], we
apply a mixed on-shell (OS) and
DR renormalization scheme
to fix the parameter and WFRCs. The free parameters of
Eq. (19) are defined to be either OS or
DR parameters as
follows
t
h
d
, t
h
u
, t
h
s
, m
2
H
±
, m
2
W
, m
2
Z
, e
OS
, tan β, v
s
,λ,κ,A
κ
DR
. (24)
The renormalization scheme for the parameters is chosen
such that the quantities which can be related to physical
observables are defined on-shell, whereas the rest of the
parameters are defined as
DR parameters.
5
In addition, we
introduce the WFRCs for the doublet and singlet fields before
rotation into the mass eigenstates as
H
d
→
Z
H
d
H
d
=
1 +
δ Z
H
d
2
H
d
(25)
H
u
→
Z
H
u
H
u
=
1 +
δ Z
H
u
2
H
u
(26)
S →
Z
S
S =
1 +
δ Z
S
2
S. (27)
We apply
DR conditions for the WFRCs of the Higgs fields.
We introduce a WFRC for the W boson field, needed in the
computation of the loop corrections to the charged Higgs
boson decay, as
W
±
→
Z
W
W
±
=
1 +
δ Z
W
2
W
±
. (28)
The WFRC δ Z
W
is defined through the OS condition
δ Z
W
=−
∂
T
WW
∂p
2
p
2
=M
2
W
, (29)
where
T
WW
denotes the transverse part of the W boson self-
energy.
The Higgs boson masses and hence the mixing matrices
receive large radiative corrections. Therefore it is necessary
to include these corrections at the highest order possible to
improve the theoretical predictions. Recently, we completed
the two-loop order O(α
2
t
) corrections to the neutral Higgs
boson masses in the CP-violating NMSSM [29], thus improv-
ing our previous results, which were available to two-loop
order O(α
t
α
s
) [28]. The Higgs boson masses corrected up to
two-loop order O(α
t
α
s
+ α
2
t
) require also the renormaliza-
tion of the top/stop sector at one-loop order. The computation
5
The tadpoles will be required to minimize the potential also at higher
orders and in this sense are called OS parameters. The electric charge
is fixed through the OS e
+
e
−
γ vertex such that this vertex does not
receive any corrections at the one-loop level in the Thomson limit. For
more details, we refer e.g. to [27].
of the two-loop corrections together with the renormalization
of the parameters in the above defined mixed OS-
DR scheme
has been described in great detail in [28,29],
6
hence we do
not repeat it here and instead refer to these references for
details. The CP-conserving limit of these results given in
the CP-violating NMSSM is straightforward, further infor-
mation can also be found in [26] where the one-loop cal-
culation is presented for the real NMSSM. We review here,
however, important points and highlight differences for the
purpose of discussing the parameter dependence. In the fol-
lowing, we focus on the CP-even Higgs bosons. Their loop-
corrected masses are defined as the real parts of the poles
of the propagator matrix. These complex poles are the zeros
of the determinant of the renormalized two-point correlation
function
ˆ
(p
2
), where p
2
denotes the external squared four-
momentum. The renormalized two-point correlation function
is expressed as
7
ˆ
(p
2
) = i
p
2
1 −
ˆ
M
2
( p
2
,ξ)
, (30)
with
ˆ
M
2
( p
2
,ξ)
=
⎛
⎜
⎝
m
2
h
1
−
ˆ
h
1
h
1
( p
2
,ξ) −
ˆ
h
1
h
2
( p
2
,ξ) −
ˆ
h
1
h
3
( p
2
,ξ)
−
ˆ
h
2
h
1
( p
2
,ξ) m
2
h
2
−
ˆ
h
2
h
2
( p
2
,ξ) −
ˆ
h
2
h
3
( p
2
,ξ)
−
ˆ
h
3
h
1
( p
2
,ξ) −
ˆ
h
3
h
2
( p
2
,ξ) m
2
h
3
−
ˆ
h
3
h
3
( p
2
,ξ)
⎞
⎟
⎠
,
(31)
where the renormalized self-energy
ˆ
h
i
h
j
( p
2
,ξ)of the tran-
sition h
i
→ h
j
(i, j = 1, 2, 3) is given by
ˆ
h
i
h
j
( p
2
,ξ)=
ˆ
1l
h
i
h
j
( p
2
,ξ)+
ˆ
α
t
α
s
h
i
h
j
(0) +
ˆ
α
2
t
h
i
h
j
(0). (32)
Here,
ˆ
1l
( p
2
,ξ)denotes the full one-loop self-energy with
full momentum-dependent contributions computed in gen-
eral R
ξ
gauge, where ξ stands for the gauge parameters
ξ
W
,ξ
Z
.
8
The last two terms are the two-loop corrections of
order O(α
t
α
s
) [28] and O(α
2
t
) [29], respectively, which are
evaluated in the approximation of vanishing external momen-
tum. These contributions do not introduce additional gauge-
dependent terms in the renormalized self-energies as they are
evaluated in the gaugeless limit. We want to point out that the
full one-loop renormalized self-energies
ˆ
1l
( p
2
,ξ)in gen-
eral R
ξ
gauge are newly computed by us and implemented
in NMSSMCALC [26–29,70–73]. We computed them both in
the standard tadpole scheme and in the Fleischer-Jegerlehner
6
The one- and/or two-loop of corrections to NMSSM Higgs boson
masses were also studied in [22,26,27,34–52].
7
Here and in the following, the hat denotes the renormalized quantity.
8
We do not consider the gauge parameter ξ
A
of the photon which is
set to unity, i.e. ξ
A
= 1. This choice does not affect the results of
our investigation and prevents the appearance of high-rank tensor loop
integrals with too many vanishing arguments that are infrared (IR)-
divergent and hence, they numerically blow up.
123