Physics Letters B 802 (2020) 135190
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Searching for a light Higgs boson via the Yukawa process at lepton
colliders
Eung Jin Chun, Tanmoy Mondal
∗
Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
a r t i c l e i n f o a b s t r a c t
Article history:
Received
27 September 2019
Received
in revised form 23 December 2019
Accepted
23 December 2019
Available
online 2 January 2020
Editor:
J. Hisano
Keywords:
Two
Higgs doublet models
Light
(pseudo)scalar
Lepton
collider
ILC
Yukawa
process
Higgs
factory
We explore the prospect of Yukawa production of a light boson which can exist in an extended Higgs
sector. A particularly interesting case is the light pseudoscalar in Type-X two Higgs doublet model which
can explain the anomalous magnetic moment of muon at large tan β. Considering ILC Higgs factory with
√
s =250 GeV, we show that the available parameter space can be fully examined by the (tau) Yukawa
process at 5σ . We also demonstrate the mass reconstruction of such a light particle which helps to
sizably minimize the background events.
© 2019 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
.
Contents
1. Introduction............................................................................................... 1
2. The
Type-X 2HDM.......................................................................................... 2
2.1. Model
basics......................................................................................... 2
2.2. Constraints
on the model................................................................................ 3
3. Search
for Yukawa process at lepton collider ....................................................................... 3
3.1. Event
simulation and selection............................................................................ 3
3.2. Collinear
approximation and reconstruction of A ............................................................... 4
4. Results ..................................................................................................
4
5. Conclusion................................................................................................
6
6. Appendix.................................................................................................
6
1. Introduction
Although the Standard Model (SM) endowed with the mini-
mal
Higgs sector is enough to explain most experimental data, it
still has room to accommodate an extension with more bosons.
In particular, the two Higgs doublet model (2HDM), where two
doublet bosons are involved in the electroweak symmetry break-
ing
(EWSB), has been motivated by supersymmetry [1], baryon
*
Corresponding author.
E-mail
addresses: ejchun@kias.re.kr (E.J. Chun), tanmoy@kias.re.kr (T. Mondal).
asymmetry of the Universe [2,3], or to resolve the strong CP prob-
lem [4].
Based on the Yukawa structure of natural flavor conser-
vation [5],
four different types of 2HDM [6–8]can be constructed.
In the spectrum of multi-Higgs bosons the presence of a relatively
light neutral one does not necessarily violate the custodial symme-
try [9] and
thus can be consistent with the electroweak precision
test [10].
A
light pseudoscalar in the Lepton-specific or Type-X 2HDM is
of particular interest as it can explain the observed anomaly of
muon anomalous magnetic moment, (g − 2)
μ
, measured by the
BNL collaboration [11,12] when the ratio of Higgs vacuum expec-
https://doi.org/10.1016/j.physletb.2019.135190
0370-2693/
© 2019 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
.