After a brief review of the muon g-2 status, we analyze the possibility that the present discrepancy between experiment and the Standard Model (SM) prediction may be due to hypothetical errors in the determination of the hadronic leading-order contribution to the latter. In particular, we show how an increase of the hadro-production cross section in low-energy e^+e^- collisions could bridge the muon g-2 discrepancy, leading however to a decrease on the electroweak upper bound on M_H, the SM Higgs boson mass. That bound is currently M_H < ~ 150GeV (95%CL) based on the preliminary top quark mass M_t = 172.6(1.4)GeV and the recent determination Δα_{\rm had}^{(5)}(M_Z) = 0.02768(22), while the direct-search lower bound is M_H > 114.4GeV (95%CL). By means of a detailed analysis we conclude that this solution of the muon g-2 discrepancy is unlikely in view of current experimental error estimates. However, if this turns out to be the solution, the 95%CL upper bound on M_H is reduced to about 130GeV which, in conjunction with the experimental lower bound, leaves a narrow window for the mass of this fundamental particle.
We describe recent work on the physics of the Higgs boson at future muon colliders. Starting from the low energy muon collider at the Higgs boson pole we extend our discussion to the multi-TeV muon collider and outline the physics case for such machines about the properties of the Higgs boson and physics beyond the Standard Model that can be possibly discovered.
The CP violating two-Higgs doublet model of type-X may enhance significantly the electric and magnetic moment of leptons through two-loop Barr-Zee diagrams. We analyze the general parameter space of the type-X 2HDM consistent with the muon $g-2$ and the electron EDM measurements to show how strongly the CP violating parameter is constrained in the region explaining the muon $ g-2$ anomaly.
The $s$-channel resonant production of the Higgs boson at a 125 GeV muon collider enables a unique way to determine the Higgs properties. However, a clear picture of the achievable Higgs precision has not yet been established. We perform a phenomenological study of the Higgs measurements at such resonant muon collider Higgs factory and present a systematic, detailed, and consistent extraction of Higgs precision measurements. Many new aspects about the lineshape scan, including the scaling with luminosity, optimal scan range, minimal scan steps, correlations with exclusive measurement, effectiv…
Data from the Muon g-2 experiment and measurements of the fine structure constant suggest that the anomalous magnetic moments of the muon and electron are at odds with standard model expectations. We survey the ability of axion-like-particles, two-Higgs-doublet models and leptoquarks to explain the discrepancies. We find that accounting for other constraints, all scenarios except the Type-I, Type-II and Type-Y two-Higgs-doublet models fit the data well.
We point out that heavy new physics contributions in leptonic dipole moments and high-energy cross-sections of lepton pairs into Higgs bosons and photons are connected model-independently. In particular, we demonstrate that a muon collider, running at center-of-mass energies of several TeV, can provide a unique test of new physics in the muon g-2 through the study of high-energy processes such as mu+ mu- -> h gamma. This high-energy test would be of the utmost importance to shed light on the long-standing muon g-2 anomaly as it is not affected by the hadronic and experimental uncertainties ent…
We study the two-Higgs-doublet model with type-II seesaw mechanism. In view of constraints from the Higgs data, we consider the aligned two-Higgs-doublet scheme and its effects on muon anomalous magnetic dipole moment, $a_μ$, including both one-loop and two-loop Barr-Zee type diagrams. Thanks to a sizable trilinear scalar coupling, the Barr-Zee type diagrams mediated by the Higgs triplet fields have a dominant effect on $a_μ$. In particular, unlike the usual two-Higgs-doublet models that require exotic Higgs bosons light in mass, the masses of the corresponding particles in the model are of ${…
We explore the sensitivity of directly testing the muon-Higgs coupling at a high-energy muon collider. This is strongly motivated if there exists new physics that is not aligned with the Standard Model Yukawa interactions which are responsible for the fermion mass generation. We illustrate a few such examples for physics beyond the Standard Model. With the accidentally small value of the muon Yukawa coupling and its subtle role in the high-energy production of multiple (vector and Higgs) bosons, we show that it is possible to measure the muon-Higgs coupling to an accuracy of ten percent for a …
Measuring the shape of the Higgs boson potential is of paramount importance and will be a challenging task at current as well as future colliders. While the expectations for the measurement of the trilinear Higgs self-coupling are rather promising, an accurate measurement of the quartic self-coupling interaction is presently considered extremely challenging even at a future 100 TeV proton-proton collider. In this work we explore the sensitivity that a muon collider with a center of mass energy in the multi-TeV range, and luminosities of the order of 10^35cm^-2s^-1, as presently under discussio…
We consider the scenario of composite Higgs with partial compositeness to address the muon g-2 anomaly. We show that this anomaly is resolved by one-loop correction due to composite muon partners with mass scale of order TeVs and large Yukawa coupling to composite Higgs, which is different from interpretations of vectorlike lepton models. We present parameter space by imposing indirect constraints from precise measurements on Higgs, Z and oblique electroweak parameters. We analyze direct constraints in light of both Drell-Yan and Higgs-associated productions of the composite muon partners at h…
A simple model for the explanation of the muon anomalous magnetic moment was proposed by the present authors within the context of the minimal supersymmetric standard model [1607.05705, 1608.06618]: "Higgs-anomaly mediation". In the setup, squarks, sleptons, and gauginos are massless at tree-level, but the Higgs doublets get large negative soft supersymmetry (SUSY) breaking masses squared $m_{H_u}^2 \simeq m_{H_d}^2 < 0$ at a certain energy scale, $M_{\rm inp}$. The sfermion masses are radiatively generated by anomaly mediation and Higgs-loop effects, and gaugino masses are solely determined b…
Can the Two-Higgs-Doublet Model Survive the Constraint from the Muon Anomalous Magnetic Moment as Suggested?
需要两个希格斯偶极子模型II，以适应3 $σ$偏差的μ子异常磁矩希格斯谱施加特定的限制。我们分析了模型参数空间上所有相关的、可用的约束的组合。从$b\to s γ$，精确的电弱测量的$R_b$，和$ρ$参数，连同排除在LEP直接搜索的约束条件的使用，给出了非常严格的限制模型参数。这“几乎足以”完全杀死该模型。如果直接搜索可以被优化以补充其他约束，则排除将更强，如将在本工作中详细讨论的。
Inverse Neutrino-less Double Beta Decay Revisited: Neutrinos, Higgs Triplets and a Muon Collider
我们重新审视了未来直线对撞机上的反中微子双β衰变（e -> W W）过程。Majorana中微子和希格斯三重态交换的情况下被认为是。我们还讨论了e mu -> W W和mu mu-> W W的过程，这是由μ子对撞机的可能性所激发的。对于重中微子交换和质心能量大于1 TeV的情况，我们证明了e-e和e-mu机器可以分别探测到10^6（10^5）GeV的质量。重中微子与μ子混合的严格限制使得μ μ-> W W不太有希望，即使这个过程不受无中微子双β衰变的限制。如果希格斯三重态是反中微子双β衰变的原因，那么只有在满足非常窄的共振时，才有可能观测到信号。我们还考虑了统一性方面的情况下，希格斯三胞胎和中微子交换的过程。发现低能数据与重中微子和三重态参数之间存在一个精确的跷跷板关系。
We estimate the expected precision at a multi-TeV muon collider for measuring the Higgs boson couplings with electroweak gauge bosons, $HVV$ and $HHVV\ (V=W^\pm,Z)$, as well as the trilinear Higgs self-coupling $HHH$. At very high energies both single and double Higgs productions rely on the vector-boson fusion (VBF) topology. The outgoing remnant particles have a strong tendency to stay in the very forward region, leading to the configuration of the "inclusive process" and making it difficult to isolate $ZZ$ fusion events from the $WW$ fusion. In the single Higgs channel, we perform a maximum…
SM-like Higgs decay into two muons at 1.4 TeV CLIC
本文将介绍在1.4 TeV CLIC中类SM希格斯玻色子衰变为两个μ子的分支分数测量结果。该研究是在CLIC的完全模拟ILD探测器概念中进行的，考虑到所有相关的物理和束诱导背景，以及非常向前的区域的仪器来标记高能电子。希格斯耦合被称为是敏感的BSM物理和我们证明，BR倍的希格斯生产截面可以测量约35.5%的统计精度在四年的CLIC操作在1.4 TeV的质心能量与非偏振光束。由于在截面计算中没有考虑等效光子近似，所以结果是初步的。这项研究补充了CLIC预见的希格斯物理学计划。
In this article, we have considered an extension of the inert Higgs doublet model with $SU(2)_L$ singlet vector like fermions. Our model is capable of addressing some interesting anomalous results in $b\to s\ell^+\ell^-$ decays (like $R(K^{(*)})$) and in muon $(g-2)$. Apart from explaining these anomalies, and being consistent with other flavour data, the model satisfies relevant constraints in the dark matter sector, while remaining within the reach of ongoing direct detection experiments. The model also produces signatures at the large hadron collider (LHC) with final states comprised of dil…
We show that new physics explanations of the muon $g-2$ anomaly by the contributions of new leptons mediated by the standard model Higgs boson necessarily lead to large rates for $μ^+ μ^- \to hh$ and $μ^+ μ^- \to hhh$ irrespectively of details of the model or the scale of new physics. For new leptons with the same quantum numbers as the standard model leptons, cross sections are expected to be about 240 ab for $μ^+ μ^- \to hh$ independently of the center of mass energy, $\sqrt{s}$, and about 2.7 ab for $μ^+ μ^- \to hhh$ for $\sqrt{s} = 1$ TeV and growing quadratically with $\sqrt{s}$. Predicti…
Probing Higgs and Top Interactions through the Muon Lens at multi-TeV Muon Colliders
Indian Institute of Technology Kanpur（坎普尔印度理工学院）；The Institute of Mathematical Sciences（数学科学研究所）；Homi Bhabha National Institute（霍米·巴巴国立学院）；Department of Physics, University of Calcutta（加尔各答大学物理系）；INFN, Sezione di Roma, c/o Dipartimento di Fisica, “Sapienza” Università di Roma（罗马大学物理系 INFN 罗马分部）
The discrepancy between the measured value and the Standard Model prediction for the muon anomalous magnetic moment is one of the important issues in the particle physics. In this paper, we consider a two Higgs doublet model (2HDM) where the extra Higgs doublet couples to muon and tau in lepton flavor violating (LFV) way and the one-loop correction involving the scalars largely contributes to the muon anomalous magnetic moment. The couplings should be sizable to explain the discrepancy, so that the extra Higgs bosons would dominantly decay into $μτ$ LFV modes, which makes the model testable at…
Laboratory for Elementary Particle Physics, Cornell University（康奈尔大学基本粒子物理实验室）；Stanford Institute for Theoretical Physics, Stanford University（斯坦福大学理论物理研究所）；Department of Physics and Astronomy, University of Sussex（萨塞克斯大学物理与天文学系）；Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology (BIST)（巴塞罗那科技研究院高能物理研究所）；ICREA, Institució Catalana de Recerca i Estudis Avançats（加泰罗尼亚研究与高等研究学院）
We discuss the discovery potential of a promising signals, $3 \times μ^+ μ^-$ at a $μ^+ μ^-$ collider and $μ^+ μ^+ μ^+ μ^+ μ^- μ^- $ at a $μ^+ μ^+$ collider, that are obtained via production of $Z'$ and a new scalar boson $ϕ$ in a spontaneously broken local $U(1)_{L_μ- L_τ}$ model. We consider the $Z'$ associated production from the process $μ^+ μ^- \to ϕZ'$ in addition to a muonphilic $Z'$ fusion process $μ^+ μ^\pm \to ϕμ^+ μ^\pm$. The scalar boson is associated with $U(1)_{L_μ- L_τ}$ symmetry breaking and dominantly decays into $Z' Z'$ mode. We carry out numerical simulation analysis for sig…
We explore the sensitivity of directly testing the muon-Higgs coupling at a high-energy muon collider. This is strongly motivated if there exists new physics that is not aligned with the Standard Model Yukawa interactions which are responsible for the fermion mass generation. We illustrate a few such examples for physics beyond the Standard Model. With the accidentally small value of the muon Yukawa coupling and its subtle role in the high-energy production of multiple (vector and Higgs) bosons, we show that it is possible to measure the muon-Higgs coupling to an accuracy of ten percent for a …
We show in this paper that, in a $U(1)$-symmetric two-Higgs-doublet model (2HDM), the two additional neutral Higgs bosons would become nearly degenerate in the large $\tanβ$ regime, under the combined constraints from both theoretical arguments and experimental measurements. As a consequence, the excess observed in the anomalous magnetic moment of the muon could not be addressed in the considered framework, following the usual argument where these two neutral scalars are required to manifest a large mass hierarchy. On the other hand, we find that, with an $\mathcal{O}(1)$ top-Yukawa coupling a…
I review possible explanations of the muon g-2 anomaly in models with extended Higgs and matter sectors, focusing on extensions of the standard model and the two Higgs doublet model with vectorlike leptons. Predictions of these models, namely the modifications of muon Yukawa and gauge couplings, that can be searched for at the LHC and future colliders, are summarized. I also discuss striking predictions for di-Higgs and tri-Higgs signals at a muon collider that can be tested even at very low energies. Furthermore, I briefly comment on other interesting features and signatures of models with ex…
A light leptophilic boson (scalar or pseudoscalar) has been postulated to explain the muon g-2 anomaly and could be a portal to dark matter. Realizing the leptophilic nature of a singlet boson in the framework of the two-Higgs-doublet-Model of type-X, we identify the parameter space viable for the explanation of the updated muon g-2 discrepancy. It is then shown that such a hypothetical particle will be unambiguously ruled out or discovered via the Yukawa process at a lepton collider designed as a Higgs factory.
