Physics Letters B 749 (2015) 464–468
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
2TeV Higgs boson and diboson excess at the LHC
Chuan-Hung Chen, Takaaki Nomura
∗
Department of Physics, National Cheng-Kung University, Tainan 70101, Taiwan
a r t i c l e i n f o a b s t r a c t
Article history:
Received
17 July 2015
Received
in revised form 11 August 2015
Accepted
11 August 2015
Available
online 14 August 2015
Editor:
J. Hisano
Diboson resonance with mass around 2 TeV in the dijet invariant mass spectrum is reported by ATLAS and
CMS experiments in proton–proton collisions at
√
s = 8 TeV. We propose that the candidate of resonance
is a heavy neutral Higgs H
0
or charged Higgs H
±
and use the extended two-Higgs-doublet (THD) to
demonstrate the potentiality. We find that the large Yukawa coupling to the first generation of quarks
can be realized in THD and the required value for producing the right resonance production cross section
is of O(0.06–0.2). Besides WW/ZZ channels, we find that if the mass of pseudoscalar A
0
satisfies the
jet mass tagging condition |m
j
−m
Z/W
| < 13 GeV, the diboson excess could be also caused by ZA
0
or
WA
0
channel.
© 2015 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
.
A resonance of around 2 TeV in the dijet invariant mass spec-
trum
is recently reported by ATLAS with the data collected at
√
s = 8 TeV and 20.3 fb
−1
[1], where each jet is recognized as
resulting from a boson decay. A moderate excess at the same
mass region is also found by CMS [2]. Since the tagged jet mass
m
j
is determined by |m
j
− m
V
| < 13 GeV, the reconstructed bo-
son
could be W or Z in the standard model (SM). The resul-
tant
significances at ATLAS in the region around 2TeV for WZ,
WW and ZZ channels are 3.4σ , 2.6σ and 2.9σ , respectively.
The associated cross sections σ(pp → R)BR(R → VV
) are in the
region of 16–30 fb, where R is the resonance and V
()
is the
weak gauge boson W /Z. In order to interpret the diboson ex-
cess,
the possible candidates are a spin-2 Kaluza–Klein mode of
the bulk Randall–Sundrum graviton [1], composite spin-1 parti-
cle [3–5],
spin-1 bosons e.g. W
/Z
[6–17], and composite spin-0
and/or spin-2 particles [18–20]. A possible interpretation by tribo-
son
mode is also discussed in Ref. [21].
We propose another alternative, where the resonance of TeV
scale is the heavy scalar boson and it could be a neutral or charged
particle. In conventional approach, due to the small couplings to
the light quarks, the difficulty for a scalar to be the resonance can-
didate
is the low production cross section. We will show how the
large couplings of scalar to the first generation of quarks work in
the framework of two-Higgs-doublet (THD). The same idea could
be applied to more general multi-Higgs models. Besides the gauge
*
Corresponding author.
E-mail
addresses: physchen@mail.ncku.edu.tw (C.-H. Chen),
nomura@mail.ncku.edu.tw (T. Nomura).
couplings of heavy neutral scalar H
0
W
+
W
−
and H
0
ZZ, which are
similar to the SM Higgs gauge couplings, THD also provides the
new interaction H
0
ZA
0
with A
0
being the pseudoscalar boson.
Basically, if the mass of A
0
satisfies the jet mass tagging at AT-
LAS,
i.e. m
A
0
∼m
W /Z
, we see that ZA
0
channel could also make a
contribution to the fully hadronic final states. However, a light A
0
in THD is excluded due to the width of H
0
being over the narrow
resonance requirement (NRR)
R
O(100) GeV [1]. The tension of
problem could be easily relaxed by extending the Higgs sector. For
instance, a light complex scalar singlet mixes with Higgs doublets.
Due to the mixing effect, the width of H
0
decaying into a light
A
0
and Z then could match the ATLAS limit. We note that since
the gluon sub-jets provide unbalanced sub-jet momenta and have
a higher number of charged-particle tracks (n
trk
), ATLAS also ap-
plies
the sub-jet analysis and imposes a cut on the n
trk
to reduce
QCD backgrounds. Hence, when the A
0
decays into quark jets, the
cut efficiency of A
0
should be same as that of Z.
As
known, the custodial symmetry is preserved in multi-Higgs-
doublet
models and ρ =m
2
W
/m
2
Z
cos
2
θ
W
= 1is guaranteed at the
tree level. Due to the custodial symmetry, the interaction H
±
W
∓
Z
is
forbidden. However, the coupling H
±
W
∓
A
0
in THD is allowed.
If m
A
0
∼ m
W /Z
, the events from W A
0
channel will be similar to
those from WZ. Similar to the case of decay H
0
→ Z A
0
, the decay
width of W A
0
channel in THD is over NRR of ATLAS. Therefore, we
need to extend the Higgs sector to get a light pseudoscalar. Hence,
in this work we are going to explore the potentiality of H
0
or H
±
as the 2 TeV resonance and investigate the influence of a pseu-
doscalar
with mass of O(100) GeV.
http://dx.doi.org/10.1016/j.physletb.2015.08.028
0370-2693/
© 2015 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
.