125 GeV希格斯对μg-2异常的MSSM调和挑战：有色与无色中介子的贡献

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本文主要探讨了在Minimal Supersymmetric Standard Model (MSSM)中的 gauge mediation 框架下，对于125 GeV希格斯玻色子质量与μ子磁矩(g-2)之间存在的矛盾问题。MSSM中的 gaugemediation 是一种常见的超对称(SUSY)破缺机制，通过规范玻色子（如SU(3), SU(2), U(1)）之间的交互来传递 SUSY 的破缺信息，从而影响粒子的质量。希格斯机制预言的125 GeV Higgs boson在实验上得到了确认，这通常需要较大的 stop (第三家庭上夸克的超对称伙伴)质量，这会导致在 gauge mediation 中μ(超对称模型中的超对称参数，控制Higgs-Higgsino之间的混合)的值增大。然而，μ子磁矩(g-2)测量结果中观察到的异常，特别是由 Fermilab 和 BNL 实验给出的，倾向于支持更小的 slepton (轻子的超对称伙伴)和 neutralino/chargino (中立和带电 SUSY粒子)质量，因为这些粒子贡献于 g-2 的量子效应。为了平衡这两种需求，研究者提出了利用有色和无色 messenger fields（传递 SUSY 破缺的媒介粒子）的质量分裂策略。有色 messenger 通常与强相互作用关联，其质量较大，而无色 messenger 负责传递电弱相互作用的破缺，它们的质量可能相对较小。通过精细调整这些媒介粒子的质量，理论上可以实现较小的 slepton 和 neutralino/chargino 质量，以解释 g-2 异常。然而，文章指出，最新的 ATLAS 实验数据更新对 wino（SU(2)双态超对称粒子）的搜索结果对该理论产生了挑战。Wino 质量与 slepton 和 neutralino/chargino 有关，因此，即使通过 mass splitting 的方法设法减小了 Slepton 和 neutralino/chargino 的质量，ATLAS 数据可能排除了所有与 μ子磁矩 g-2 异常相一致的参数区域。这表明，尽管有理论上的可能性，但在当前的实验约束下，MSSM 的 gauge mediation 解释 μ子磁矩异常可能面临困难。该研究重申了 MSSM 中 gauge mediation 对 μ子磁矩异常的潜在解释，但同时也揭示了与最新实验数据之间的不协调，这可能是对现有模型或需要进一步探索的新物理现象的信号。未来的研究可能会集中在寻找其他 SUSY 参数组合、新的 mediation 机制，或者可能需要考虑超对称的非标准实现，以解决这个理论与实验之间的矛盾。

Physics Letters B 772 (2017) 409–414

Contents lists available at ScienceDirect

Physics Letters B

www.elsevier.com/locate/physletb

Muon g − 2in MSSM gauge mediation revisited

Tsutomu T. Yanagida

a,1

, Norimi Yokozaki

b,∗

Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Kashiwa 277-8583, Japan

Department of Physics, Tohoku University, Sendai, Miyagi 980-8578, Japan

a r t i c l e i n f o a b s t r a c t

Article history:

Received

10 April 2017

Received

in revised form 23 June 2017

Accepted

1 July 2017

Available

online 8 July 2017

Editor:

J. Hisano

The Higgs boson of 125 GeV requires large stop masses, leading to the large μ-parameter in most

cases of gauge mediation. On the other hand, the explanation for the muon g − 2anomaly needs

small slepton and neutralino/chargino masses. Such disparity in masses may be obtained from a mass

splitting of colored and non-colored messenger ﬁelds. However, even if the required small slepton and

neutralino/chargino masses are realized, all parameter regions consistent with the muon g − 2are

excluded by the recent updated ATLAS result on the wino search in the case that the messenger ﬁelds

are in 5 +

5 representations of SU(5). It is also revealed that the messenger ﬁelds in 10 + 10 or 24

representation

can not explain the muon g − 2anomaly. We show, giving a simple example model, that

the above conﬂiction is solved if there is an additional contribution to the Higgs soft mass which makes

the μ-parameter small. We also show that the required Higgs B-term for the electroweak symmetry

breaking is consistently generated by radiative corrections from gaugino loops.

(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP

1. Introduction

The anomalous magnetic moment of the muon (muon g − 2)

was precisely measured by the Brookhaven E821 experiment [1,2].

The measured value deviates from the standard model (SM) pre-

diction

as [3]

)

exp

− (a

)

= (26.1 ± 8.0) × 10

−10

, (1)

which is at more than 3σ level. Also, Davier et al. has reported

a deviation of 3.6σ level [4,5]. This anomaly might be a signal of

the physics beyond the SM. One of the attractive explanations for

the muon g − 2 anomaly is given by supersymmetry (SUSY). In

the minimal SUSY extension of the SM (MSSM), the anomaly of

the muon g − 2is explained with light sleptons, neutralino and/or

chargino of O(100) GeV [6–8].

Such

a low-scale SUSY is, in general, very severely constrained

by ﬂavor changing neutral-current processes because of the light-

ness

of the sleptons. This fact motivates us to consider SUSY break-

ing

mediation models where soft SUSY breaking masses arise in a

ﬂavor independent way. In gauge mediated SUSY breaking (GMSB)

scenarios [9–11] (for early attempts [12–16]), the SUSY breaking of

the hidden sector is mediated to the visible sector via gauge in-

teractions,

and the generated soft masses are ﬂavor independent;

Corresponding author.

E-mail

address: yokozaki@truth.phys.tohoku.ac.jp (N. Yokozaki).

Hamamatsu Professor.

therefore, GMSB models are attractive candidates for the low-scale

SUSY.

In most GMSB models, the Higgs boson mass of 125 GeV re-

quires

heavy stops of masses ∼10 TeV [17–21], due to the small-

ness

of trilinear couplings of the stops. With the heavy stops,

the higgsino mass parameter, μ, should be taken as large as sev-

eral

TeV for generating the correct electroweak symmetry breaking

(EWSB). In these cases, the chargino contribution to the muon

g −2is suppressed and the explanation of the muon g − 2 anomaly

requires the quite light sleptons, bino and wino.

The mass split-

ting

of the colored (squarks and a gluino) and non-colored SUSY

particles (sleptons, neutralinos and charginos) may be realized

from a mass splitting of colored and non-colored messenger ﬁelds

[22–25]. However, the lightest neturalino/chargino is almost purely

wino-like for the large μ-parameter, and its mass is predicted be-

low

400 GeV. This wino has been excluded by the recent updated

ATLAS result on the wino search [26]: the wino should be heavier

than 430 GeV. This conﬂiction can be avoided in the case of an ad-

joint

messenger transforming as 24 in SU(5) gauge group. We will

show that this case is, however, also excluded since the stau is too

light and long-lived (see [27,28] for the LHC bounds). So far, in the

cases that the messenger ﬁelds are in 5 +

5, 10 + 10 or 24 repre-

sentation

of SU(5), the muon g − 2 anomaly can not be explained

without an extension.

The heavier wino makes the slepton masses larger via radiative corrections.

http://dx.doi.org/10.1016/j.physletb.2017.07.002

0370-2693/

SCOAP

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