Single charged Higgs boson production at the LHC A. Arhrib3R. Benbrik2M. Krab1B. Manaut1M. Ouchemhou2and Qi-Shu Yan45uni2016 1Research Laboratory in Physics and Engineering Sciences Modern and Applied Physics Team

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Single charged Higgs boson production at the LHC

A. Arhrib3∗R. Benbrik,2†M. Krab,1‡B. Manaut,1§M. Ouchemhou,2¶and Qi-Shu Yan4,5‖

1Research Laboratory in Physics and Engineering Sciences, Modern and Applied Physics Team,

Polidisciplinary Faculty, Beni Mellal, 23000, Morocco

2Polydisciplinary Faculty, Laboratory of Fundamental and Applied Physics, Cadi Ayyad

University, Sidi Bouzid, B.P. 4162, Saﬁ, Morocco

3Abdelmalek Essaadi University, Faculty of Sciences and techniques, Tanger, Morocco

4Center for Future High Energy Physics, Chinese Academy of Sciences, Beijing 100049, PR

China.

5School of Physics Sciences, University of Chinese Academy of Sciences, Beijing 100039, PR

China.

Abstract

A search for charged Higgs may yield clear and direct signs of new physics outside the realm of

the Standard Model (SM). In the Two-Higgs Doublet Model (2HDM), we investigate two of the

main single charged Higgs production channels at the Large Hadron Collider (LHC), assuming

that either hor Hreplicates the detected resonance at ∼125 GeV. We consider the possibility

of the charged Higgs boson production through the pp →H±W∓and pp →H±bj production

processes that may present additional signiﬁcance at the LHC experiments. Considering the

H±→W±hi/A decay channels and mainly concentrating on the b¯

b,ττ and γγ decays of

hiand A, we examine the possible signatures arising from the aforementioned charged Higgs

production and decay in both type-I and type-X realizations of 2HDM. Our study shows that

these signatures can have sizable rates at low tan βas long as the condition MH±< mt−mb

is satisﬁed. As a result, we propose the bb,ττ and γγ ﬁnal states associated with W W or W bj

as an encouraging experimental avenue that would complement the LHC search for a charged

Higgs boson.

1 Introduction

The discovery of the Higgs boson was made possible through the CERN Large Hadron Collider

(LHC). The ﬁrst observation of such a particle was reported by the two collaborations ATLAS and

CMS [1,2] in 2012. Regarding particle content, this is the ultimate and one of the most signiﬁcant

discoveries inside the Standard Model (SM) of particle physics. Although, due to many theoretical

and experimental reasons, the SM Higgs boson is widely assumed not to be the only fundamental

particle with spin zero. Many theories extending the SM exist and predict the existence of a new

charged particle(s) with spin zero. Direct searches for this charged Higgs boson(s) have already been

conducted at LEP [3], Tevatron [4], and now at the LHC [5,6], all yielding negative results. As a

consequence, depending on the charged Higgs boson mass, constraints are placed on the branching

ratios of diﬀerent decay channels for the charged Higgs boson. The LEP experiment excludes

∗aarhrib@gmail.com

†r.benbrik@uca.ma

‡mohamed.krab@usms.ac.ma

§b.manaut@usms.ma

¶mohamed.ouchemhou@ced.uca.ac.ma

‖yanqishu@ucas.ac.cn

arXiv:2210.09416v1 [hep-ph] 17 Oct 2022

the mass of charged Higgs below 80 GeV at 95% CL, considering only the decays H+→c¯s

and H+→τντwith BR(H+→c¯s) + BR(H+→τ ντ) = 1 [7]. Such a bound gets stronger if

BR(H+→τντ) = 1 [8]. For a charged Higgs mass of 100 GeV, searches at the Tevatron based on

top anti-top pair production with the subsequent t→bH+decay (setting BR(H+→τ+ν) = 1)

have set a limit on BR(t→bH+) to be less than 0.2 [9]. LHC searches for H±have set an upper

limit at 95% conﬁdence level on the production cross section multiplied by the branching ratio,

σ(pp →H±tb)×BR(H±→tb), which ranges from 3.6 (2.6) pb at MH±= 200 GeV to 0.036 (0.019)

pb at MH±= 2 TeV. The discovery prospects of the charged Higgs boson in other independent

frameworks can be found in Refs. [10,11].

The Two-Higgs-Doublet Model (2HDM) is a simplest beyond SM framework that predicts the

charged Higgs bosons, where an additional complex doublet Φ2was added to the SM Higgs sector.

In order to prevent the Flavor Changing Neutral Currents (FCNCs) at the tree-level [12], a Z2

symmetry was introduced (Φ1→Φ1,Φ2→ −Φ2), leading to four distinct interaction modes [13],

when it is expanded to include the model’s fermions, known as in this context, type-I, type-II, type-

X (or lepton-speciﬁc) and, type-Y (or ﬂipped). These models are widely discussed in the literature,

and both direct and indirect constraints are set on them. The former is already set above and

excludes the charged Higgs boson with a mass less than 80 GeV at 95% CL, while the latter is

model-dependent and dominated by the B-physics decay, mainly through, B→Xsγ[14]. A light

charged Higgs boson with a mass below 100 GeV is still allowed in type-I and type-X as long as

tan βis larger than 2. However, such constraints are very strong in type-II and type-Y, excluding

a charged Higgs mass below 680 GeV. The last update on this constraint B→Xsγ[15] excludes

MH±below 800 GeV in type-II and type-Y, while type-I and type-X are still accommodated the

light charged Higgs Boson below 100 GeV.

At the LHC, the hunt for the charged Higgs boson were performed with many distinct production

modes, starting with the most promising one, which is the t¯

tproduction and decay, which represents

an excellent source of H±when MH±< mt−mb. The top (anti-top) quark could decay into

H+b(H−¯

b), competing with the SM decay of t→W+b(¯

t→W−¯

b). The production process

pp →t¯

t→b¯

bH−W++ C.C.has a sizable cross section that can serve as a signiﬁcant supply of

light charged Higgs bosons. In addition, the following production modes might be used to look for

light charged Higgs at the LHC: associated production with top and bottom quarks considering

either the gg →t¯

bH+process in the four-ﬂavor scheme or the g¯

b→tH+process in the ﬁve-

ﬂavor scheme [16,17], associated production with a Wboson through b¯

b→H±W∓, which is

dominated at tree-level, and gg →H±W∓that is dominated at loop-level [18–20], associated

production with a bottom quark and a light quark [21,22], resonant production via the quark

anti-quark collision c¯s, c¯

b→H+[23–25], associated production with a neutral Higgs states hior

A,q¯q0→H±hi/A [26–31], where histand for hand H, as well as the pair production through the

annihilation process q¯q→H±H∓or gluon fusion gg →H±H∓[32–35].

This work aims to examine the production of single charged Higgs boson along with a W

boson as well as with a bottom quark and a light jet, i.e. pp →H±W∓and pp →H±bj, in

the 2HDM type-I and type-X frameworks. These models still predict a light charged Higgs boson

with signiﬁcant rates of its bosonic decays that potentially dominate over fermionic modes. We

study the diﬀerent possible LHC signatures stemming from the aforementioned Higgs production

channels and the bosonic decays H±→W±hi/A as well as their phenomenological implications in

the context of the LHC.

This paper is structured as follows. We brieﬂy introduce the 2HDM framework in Section 2.

In Section 3, we outline the theoretical and experimental constraints that will be forced on 2HDM

parameter space during our scan. In Section 4, we study the charged Higgs production at the LHC.

Our LHC signatures are discussed in Section 5and our conclusions are given in Section 6.

2 The two-Higgs doublet model

Upon the soft broken Z2symmetry, the scalar potential that is SU (2)L⊗U(1)Yinvariant and

CP-conserving is given by:

V2HDM(Φ1,Φ2) = m2

11(Φ+

1Φ1) + m2

22(Φ+

2Φ2)−m2

12(Φ+

1Φ2+ h.c.)

+λ1(Φ+

1Φ1)2+λ2(Φ+

2Φ2)2+λ3(Φ+

1Φ1)(Φ+

2Φ2)

+λ4(Φ+

1Φ2)(Φ+

2Φ1) + λ5

2[(Φ+

1Φ2)2+ h.c.],(1)

where all parameters are real valued due to the CP-conserving requirement. m2

11,m2

22 and m2

are mass parameters, and λ1−5are coupling parameters without dimensions. Spontaneous Electro-

Weak Symmetry Breaking (EWSB) allows Φ1and Φ2doublets to gain vacuum expectation values

denote as v1,2, which satisfy v2

1+v2

2=v2≈(246 GeV)2. In addition, during the (EWSB), we

left with ten free independent parameters: m2

11, m2

22, m2

12, v1, v2and λ1−5. Through the two

minimization conditions of the potential, replacing m2

11 and m2

22 by v1,2, we are left with the seven

free independent, real, parameters: λ1−5, m2

12,tan β(= v2/v1). Instead, for more convenience, we

adopt the following physical parameters: Mh, MH, MA, MH±, α, tan β, m2

12. The angle β(α) is

the rotation angle from the group eigenstate to the mass eigenstate in the charged Higgs and the

CP-odd (CP-even) Higgs sector.

In order to suppress FCNCs, the Yukawa sector of general 2HDM is constrained by Z2symmetry,

which implies that each fermion type is only allowed to interact with one of the Higgs doublets

Φ1,2. Such a requirement gives rise to four diﬀerent versions of Yukawa interactions carrying the

names 2HDM type-I, type-II, type-X and, type-Y. In type-I, the mass of fermions is generated by

the doublet Φ2. In type-II, leptons and down quarks receive mass from the doublet Φ1, while up

quarks receive mass from the doublet Φ2. In type-X, the quarks interact with Φ2, while the charged

leptons interact with Φ1. In type-Y, down quarks interact with Φ1, whereas the rest of the fermion

types (up-type quarks and leptons) interact with Φ2. Here, we only target the 2HDM type-I and

type-X.

In the mass eigenstate basis, the interactions between the fermion and Higgs sector, is described

by the Yukawa Lagrangian [36],

−LYukawa =X

f=u,d,l mf

vξh

f¯

ffh +mf

vξH

f¯

ffH −imf

vξA

f¯

fγ5fA+

Vud

√2v¯u(muξA

uPL+mdξA

dPR)dH++mlξA

√2v¯νLlRH++ h.c.,(2)

where Vud represents a CKM matrix element. the coeﬃcients ξhi,A

fare 2HDM Higgs couplings to

fermions normalized to the SM couplings, which are listed in Table 1.

ξh

uξh

dξh

lξH

uξH

dξH

lξA

uξA

dξA

type-I cα/sβcα/sβcα/sβsα/sβsα/sβsα/sβcβ/sβ−cβ/sβ−cβ/sβ

type-X cα/sβcα/sβ−sα/cβsα/sβsα/sβcα/cβcβ/sβ−cβ/sβsβ/cβ

Table 1: Yukawa couplings of 2HDM Higgs bosons to the fermions.

3 Parameter space scans and constraints

We randomly scan the parameters of the 2HDM type-I and type-X using the public code 2HDMC-1.8.0

[37], considering both Normal Scenario (NS) and Inverted Scenario (IS), i.e. the observed 125 GeV

Higgs boson at the LHC is assigned to either CP-even states h(NS) or H(IS), in the ranges

illustrated in Table 2. We require each point to be subjected to the updated experimental and

theoretical constraints.

Mh[GeV] MH[GeV] MA[GeV] MH±[GeV] sin(β−α) tan β m2

12 [GeV2]

NS 125.09 [126; 700] [15; 700] [80; 700] [0.95; 1] [2; 25] [0; m2

Hcos βsin β]

IS [15; 120] 125.09 [15; 700] [80; 700] [−0.5; 0.5] [2; 25] [0; m2

hcos βsin β]

Table 2: 2HDM type-I and type-X input parameters.

From the theoretical side, the perturbativity, vacuum stability, and unitarity constraints are

enforced as the following:

•Vacuum stability to get a global minimum and not only a local vacum. We should force the

following conditions [38,39],

λ1>0, λ2>0, λ3>−pλ1λ2, λ3+λ4− |λ5|>−pλ1λ2.(3)

•Unitarity constraints require that the scattering amplitudes of scalar-scalar(vector) and vector-

vector to be unitary at high energies. This requirement reﬂects certain limits on the eigen-

values of the S-matrix of such scattering processes as follows ei≤4π[40–42], which in turn,

aﬀect the potential parameter by the requirement ei=f(λi).

•Perturbativity constraints demand to all quartic scalar couplings to be perturbative, i.e. to

fulﬁll the limit λi≤4π[43].

The parameters that survive the theoretical constraints above are furthermore asked to satisfy the

following experimental constraints:

•The electroweak oblique parameters Sand T(setting U= 0) [44,45] are imposed to set limits

on the mass separation between the 2HDM Higgs states using the following ﬁt result [46]:

S= 0.05 ±0.08, T = 0.09 ±0.07, ρST = 0.92,(4)

where ρST is the correlation coeﬃcient between Sand T.

•Constraints from additional Higgs bosons searches at collider experiments are imposed using

the tool HiggsBounds-5.10.2 [47].

•Agreement with SM-like Higgs signal measurements are tested using HiggsSignals-2.6.2

[48]. We enforce to the predicted Higgs signal strengths to be compatible with the experi-

mental measurements at 95% CL.

•Flavor physics constraints are checked using the tool SuperIso v4.1 [49]. Relevant observ-

ables are listed bellow [14].

–BR(B→Xsγ)Eγ≥1.6 GeV = (3.32 ±0.15) ×10−4,

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SinglechargedHiggsbosonproductionattheLHCA.Arhrib3*R.Benbrik,2M.Krab,1B.Manaut,1§M.Ouchemhou,2¶andQi-ShuYan4;51ResearchLaboratoryinPhysicsandEngineeringSciences,ModernandAppliedPhysicsTeam,PolidisciplinaryFaculty,BeniMellal,23000,Morocco2PolydisciplinaryFaculty,LaboratoryofFundamentalandAppliedPh...

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Single charged Higgs boson production at the LHC A. Arhrib3R. Benbrik2M. Krab1B. Manaut1M. Ouchemhou2and Qi-Shu Yan45uni2016 1Research Laboratory in Physics and Engineering Sciences Modern and Applied Physics Team

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