P3H22105 TTP22064 Collider probe of heavy additional Higgs bosons solving the muon g2 and dark matter problems

2025-05-06 0 0 4.49MB 9 页 10玖币

侵权投诉

P3H–22–105, TTP22–064

Collider probe of heavy additional Higgs bosons solving the muon g−2

and dark matter problems

Monika Blanke1, 2, ∗and Syuhei Iguro1, 2, †

1Institute for Theoretical Particle Physics (TTP),

Karlsruhe Institute of Technology (KIT), Engesserstraße 7, 76131 Karlsruhe, Germany

2Institute for Astroparticle Physics (IAP), Karlsruhe Institute of Technology (KIT),

Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

We study the Large Hadron Collider (LHC) search potential of a Z4-based two Higgs doublet model

which can simultaneously explain the muon g−2 anomaly and the observed dark matter. The neutral

scalars in the second Higgs doublet couple to µand τand largely contribute to the muon anomalous

magnetic moment through the one-loop diagram involving τand scalars. An additional singlet scalar

which is charged under the discrete symmetry can be a dark matter candidate. An upper limit on the

scalar mass originates from the unitarity constraint, and the µτ ﬂavor-violating nature of the scalars

predicts non-standard signatures at the LHC. However, the previously proposed µ±µ±τ∓τ∓signal

via the electroweak heavy neutral scalar pair production at the LHC loses sensitivity for increasing

scalar mass. We revisit this model and investigate the LHC prospects for the single production of

the µτ ﬂavor-violating neutral scalar. It is shown that the single scalar process helps to extend the

LHC reach to the 1 TeV mass regime of the scenario. The search potential at the high energy LHC

is also discussed.

———————————————————————————————————————————

Keywords: Multi-Higgs Models, Muon g−2, Dark Matter, Large Hadron Collider

I. INTRODUCTION

Most experimental results so far support the standard

model (SM) of particle physics. However, the SM falls

short of explaining dark matter, the baryon asymmetry

of the universe, neutrino masses and so on. Each of these

problem has many possible solutions, and thus more ex-

perimental hints are required to specify the correct new

physics (NP) scenario. One of the most notorious and

long-lived discrepancies between the SM prediction and

the measurement exists in the muon anomalous magnetic

moment (aµ) [1–3]. The comparison of the SM prediction

with the experimental value is given as

∆aµ=aexp

µ−aSM

µ= (2.51 ±0.59) ×10−9.(1)

The SM prediction is taken from the theory white pa-

per [1]#1 which is mainly based on the data-driven de-

termination of the hadronic vacuum-polarization contri-

bution.#2 It is known that the discrepancy is of the

same order as the electroweak contribution, i. e. a new

O(100) GeV weakly coupled particle can explain the dis-

crepancy. However, no signal of NP at this scale has been

found at the Large Hadron Collider (LHC) so far. This

fact implies that in order to explain the discrepancy in

∗monika.blanke@kit.edu

†igurosyuhei@gmail.com

#1 See Refs. [4–23] for relevant original work.

#2 We note that the estimate based on the recent lattice simulation

diﬀers and is more consistent with the measured muon g−2

[24–26]. Recent results from other lattice groups are converging

towards the BMW result [24,27]. However, the lattice results are

in tension with the low energy σ(e+e−→hadrons) data [28–30],

so that further clariﬁcation is needed. In this paper we consider

the discrepancy as quoted in Eq. (1).

terms of NP, some enhancement mechanism in the NP

contribution to g−2 is necessary.#3

A popular method to enhance the g−2 contribu-

tion is the introduction of a new ﬂavor-violating particle.

The dipole operator underlying g−2 requires a chirality

ﬂip, which corresponds to the muon mass within ﬂavor-

conserving scenarios. A one-loop contribution involving

aµτ ﬂavor-violating particle is instead enhanced by a

factor of mτ/mµ'17 [32–60].#4 This mechanism can

lift the mass scale of the new particle by more than a

factor of four. However, lepton ﬂavor-violating (LFV)

interactions are stringently constrained and easily spoil

the model if the particle also has lepton ﬂavor-conserving

couplings. Therefore one needs to ensure the absence of

ﬂavor-diagonal couplings for the τmass enhanced muon

g−2 solution to be viable.

This speciﬁc coupling alignment can be realized by a

discrete Z4ﬂavor symmetry within the two Higgs doublet

model (2HDM) [45].#5 In this model the g−2 contri-

bution is proportional to the µτ LFV coupling and the

mass diﬀerence of the additional neutral scalars. Re-

cently it was proposed that the singlet scalar extension

of the model can explain the relic density of the dark

matter (DM) through the thermal freeze-out mechanism

[60]. The Z4symmetry is then used both to stabilize the

DM candidate and also to realize the ﬂavor alignment.

Since the new scalars are quark-phobic within the Z4-

based model, their production cross section at the LHC

is not large. However, the unique coupling structure

#3 See Ref. [31] for a recent review.

#4 Due to the loop function, scalar mediators receive a further en-

hancement.

#5 Note that a Z4-symmetric 2HDM always carries an accidental

U(1) symmetry [61], however further extensions of the scalar

sector can break the latter symmetry [62].

arXiv:2210.13508v2 [hep-ph] 5 May 2023

FIG. 1. Representative Feynman diagrams that contribute to the µ±µ±τ∓τ∓signal at the LHC. The left diagram displays

the electroweak pair production channel. The middle and right diagrams correspond to the single production process where φ

denotes Aor H. In addition, there are also contributions obtained by exchanging µand τwhich are included in our numerical

calculation.

predicts that the neutral scalars φ=A, H decay into

µ±τ∓. Previously we pointed out the smoking-gun sig-

nature of a µ±µ±τ∓τ∓ﬁnal state via electroweak scalar

pair production (left of Fig. 1) with a special focus on the

case where all Yukawa and scalar potential couplings are

smaller than one [47]. We argued that the full Run 2 data

set can test the model up to 500 GeV scalar mass thanks

to the very unique double µτ LFV resonance nature of

the signal events. However, if we accept relatively large

coupling of O(1), the model can still explain the discrep-

ancy with 1 TeV scalars.

In this paper we revisit the model’s collider prospects

in the presence of larger couplings. The pair production

cross section is governed only by the electroweak coupling

and decreases rapidly when the scalars get heavier. We

thus propose the single scalar production process (middle

and right of Fig. 1) to assist to cover the heavier scalar

scenario. To search for the heavy lepto-philic bosons, it is

known that the inclusion of photon-initiated processes is

important [51]. We combine those processes and evaluate

the search potential at the future LHC.

The layout of the paper is given as follows. In Sec. II,

we brieﬂy introduce our setup of the 2HDM and review

the muon g−2 explanation. There we determine how

heavy the scalar can be and discuss relevant constraints.

In Sec. III, we focus on the collider phenomenology and

show the impact of the single scalar production process

to evaluate the future LHC reach. Sec. IV is devoted to

the summary and discussion.

II. MODEL, MUON g−2AND DARK MATTER

We consider a two Higgs doublet model with an ad-

ditional scalar singlet (S) and a discrete Z4symmetry

under which the Higgs and lepton ﬁelds transform as

given in Tab. I. The gauge charge assignments of other

SM ﬁelds, e. g. quarks, are the same as in the SM, and

they trivially transform under Z4.#6

We assume the Z4symmetry to be unaﬀected by elec-

troweak symmetry breaking, so that the two Higgs dou-

#6 In order to obtain realistic neutrino masses and mixings the

model needs to be extended. See Ref. [60] for details.

Field H1H2(Le, Lµ, Lτ) (eR, µR, τR)S

SM gauge (1,2)1/2(1,2)1/2(1,2)−1/2(1,1)−1(1,1)0

Z41−1 (1, i, −i) (1, i, −i)i

TABLE I. Relevant ﬁeld content and charge assignment of the

model. The notation of SM gauge quantum numbers is given

as (SU(3)C, SU(2)L)U(1)Y.

blets H1,2are in the Higgs basis [63,64] in which only

one Higgs doublet has a non-vanishing vacuum expecta-

tion value (vev) of v'246 GeV. In this basis, the two

Higgs doublets can be decomposed as

H1= G+

v+h+iG

√2!, H2= H+

H+iA

√2!,(2)

where G+and Gare the SM Nambu-Goldstone bosons,

and H+and hare a charged Higgs boson and the dis-

covered CP-even Higgs boson, respectively. Hand A

correspond to additional neutral scalars. Note that a

non-zero vev of the singlet Swould spontaneously break

the Z4symmetry. The presence of hSi 6= 0 would not

alter the phenomenology discussed in the present paper,

hence we do not discuss this possibility further.

The scalar potential of our model is given by [60]

V=M2

1H†

1H1+M2

2H†

2H2+λ1(H†

1H1)2+λ2(H†

2H2)2

+λ3(H†

1H1)(H†

2H2) + λ4(H†

1H2)(H†

2H1)

+λ5

2h(H†

1H2)2+ h.c.i

+M2

S|S|2+λS|S|4+λ0

SS4+ h.c.+λS1(H†

1H1)|S|2

+λS2(H†

2H2)|S|2+κh(H†

1H2)S2+ h.c.i.(3)

Since the mass spectrum of the scalars is of crucial im-

portance for the muon g−2 as well as the collider phe-

nomenology, we explicitly show the mass relations:

h=λ1v2, m2

A=M2

2+λ3+λ4−λ5

2v2,

H=m2

A+λ5v2, m2

H±=m2

A−λ4−λ5

2v2,

S=M2

S+λS1

2v2.(4)

文档加载中……请稍候！
如果长时间未打开，您也可以点击刷新试试。

下载文档到电脑，查找使用更方便

10 玖币 0人已下载

立即下载

摘要：

P3H{22{105,TTP22{064ColliderprobeofheavyadditionalHiggsbosonssolvingthemuong2anddarkmatterproblemsMonikaBlanke1,2,andSyuheiIguro1,2,y1InstituteforTheoreticalParticlePhysics(TTP),KarlsruheInstituteofTechnology(KIT),Engesserstrae7,76131Karlsruhe,Germany2InstituteforAstroparticlePhysics(IAP),Karlsruh...

展开>> 收起<<

P3H22105 TTP22064 Collider probe of heavy additional Higgs bosons solving the muon g2 and dark matter problems.pdf

共9页,预览2页

还剩页未读，继续阅读

声明：本站为文档C2C交易模式，即用户上传的文档直接被用户下载，本站只是中间服务平台，本站所有文档下载所得的收益归上传人(含作者)所有。玖贝云文库仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私，请立即通知玖贝云文库，我们立即给予删除！

P3H22105 TTP22064 Collider probe of heavy additional Higgs bosons solving the muon g2 and dark matter problems

相关推荐

开通VIP享超值会员特权

作者详情

相关内容

热门标签

举报选择: