ATLAS discovery potential for a heavy charged Higgs boson

The sensitivity of the ATLAS detector to the discovery of a heavy charged Higgs boson is presented. Assuming a heavy SUSY spectrum, the most promising channels above the top quark mass are H^± → tb and H^± → τ^±ν_τ which provide coverage in the low and high tanβ regions up to ∼ 600 GeV. The achievable precisions on the charged Higgs mass and tanβ determination are also discussed. The H^± → W^± h⁰ channel, though restricted to a small MSSM parameter space, shows a viable signal in NMSSM where the parameter space is less constrained. The observation of the channel H⁻ → τ⁻_L ν_τ + c.c. may constitute a distinctive evidence for models with singlet neutrinos in large extra dimensions.     

Implications of the Higgs boson discovery

With the discovery of the Higgs boson by the LHC in 2012, a new era started in which we have direct experimental information on the physics behind the breaking of the electroweak (EW) symmetry. This breaking plays a fundamental role in our understanding of particle physics and sits at the high-energy frontier beyond which we expect new physics that supersedes the Standard Model (SM). In this review we summarize what we have learned so far from LHC data in this respect. In the absence of new particles having been discovered, we discuss how the scrutiny of the properties of the Higgs boson (in search for deviations from SM expectations) is crucial as it can point the way for physics beyond the SM. We also emphasize how the value of the Higgs mass could have far-reaching implications for the stability of the EW vacuum if there is no new physics up to extremely large energies.     

The Higgs boson discovery and measurements

The discovery of the Higgs boson at a mass around 125 GeV by the ATLAS and CMS experiments at the LHC collider in 2012 establishes a new landscape in high-energy physics. The analysis of the full data sample collected with pp collisions at centre-of-mass energies of 7 and 8 TeV has allowed for considerable progress since the discovery. A review of the latest results is presented.     

希格斯玻色子发现简史

希格斯玻色子于2012年的发现是粒子物理发展史上的一座里程碑。它为标准模型补上了最后一块拼图,希格斯机制的提出者们也因此获得了2013年的诺贝尔物理学奖。在希格斯玻色子发现十周年之际,文章将带领读者简短回顾希格斯玻色子从提出到发现的近半个世纪的历史。     

Search for a Higgs boson decaying into two photons in the CMS detector

A search for a Higgs boson decaying into two photons in pp collisions at the LHC at a centre-of-mass energy of 7 TeV is presented. The analysis is performed on a dataset corresponding to 1.66 fb^?1 of data recorded in 2011 by the CMS experiment. Limits are set on the cross-section of a Standard Model Higgs boson decaying into two photons, and on the cross-section of a fermiophobic Higgs boson decaying into two photons.     

Vector boson decays of the Higgs boson

We derive the width of the Higgs boson into vector bosons. General formulas are derived both for the on–shell decay as well for the off–shell decays, and , where . For the off-shell decays the width of the decaying vector boson is properly included. The formulas are valid both for the Standard Model as well as for arbitrary extensions. As an example we study in detail the gauge-invariant effective Lagrangian models where we can have sizable enhancements over the Standard Model that could be observed at LEP. Received: 31 July 1998 / Revised version: 23 September 1998 / Published online: 6 November 1998     

Discovery of the Higgs boson by the ATLAS and CMS experiments at the LHC

The Standard Model (SM) Higgs boson was predicted by theorists in the 1960s during the development of the electroweak theory. Prior to the startup of the CERN Large Hadron Collider (LHC), experimental searches found no evidence of the Higgs boson. In July 2012, the ATLAS and CMS experiments at the LHC reported the discovery of a new boson in their searches for the SM Higgs boson. Subsequent experimental studies have revealed the spin-0 nature of this new boson and found its couplings to SM particles consistent to those of a Higgs boson. These measurements confirmed the newly discovered boson is indeed a Higgs boson. More measurements will be performed to compare the properties of the Higgs boson with the SM predictions.     

Light Higgs boson in the NMSSM confronted with the CMS di-photon and di-tau excesses

In 2018, the CMS collaboration reported a di-photon excess at approximately 95.3 GeV with a local significance of 2.8 σ. Interestingly, the CMS collaboration also recently reported a di-tau excess at 95-100 GeV with a local significance of 2.6-3.1 σ. In addition, a bb excess at 98 GeV with a local significance of 2.3 σ was reported from LEP data approximately twenty years ago. In this study, we addressed the interpretation of these excesses together with a light Higgs boson in the next-to-minima...     

Higgs boson cosmology

The discovery of the Standard Model Higgs boson opens up a range of speculative cosmological scenarios, from the formation of structure in the early universe immediately after the big bang, to relics from the electroweak phase transition one nanosecond after the big bang, on to the end of the present-day universe through vacuum decay. Higgs physics is wide ranging, and gives an impetus to go beyond the Standard Models of particle physics and cosmology to explore the physics of ultra-high energies and quantum gravity.     

Finite theories before and after the discovery of a Higgs boson at the LHC

Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories (GUTs) which can be made finite to all‐loop orders, based on the principle of reduction of couplings, and therefore are provided with a large predictive power. Confronting the predictions of SU(5) FUTs with the top and bottom quark masses and other low‐energy experimental constraints a light Higgs‐boson mass in the range M_h ∼ 121–126 GeV was predicted, in striking agreement with the recent discovery of a Higgs‐like state around ∼ 125.5 GeV at ATLAS and CMS. Furthermore the favoured model, a finiteness constrained version of the MSSM, naturally predicts a relatively heavy spectrum with coloured supersymmetric particles above ∼ 1.5 TeV, consistent with the non‐observation of those particles at the LHC. Restricting further the best FUT's parameter space according to the discovery of a Higgs‐like state and B‐physics observables we find predictions for the rest of the Higgs masses and the supersymmetric particle spectrum.     

The ATLAS discovery potential for a heavy charged Higgs boson in gg → tbH± with H± → tb

The European Physical Journal C - The feasibility of detecting a heavy charged Higgs boson, mH±>m t +m b , decaying in the H±→ tb channel is studied with the fast simulation...     

Dilaton as the Higgs boson

We propose a model where the role of the electroweak Higgs field is played by the dilaton. The model contains terms which explicitly violate gauge invariance; however, it is shown that this violation is fictitious, so that the model is a consistent low-energy effective theory. In the simplest version of the idea the resulting low-energy effective theory is the same as the top mode standard model.     

Taming the off-shell Higgs boson

Journal of Experimental and Theoretical Physics - We study the off-shell Higgs data in the process pp → h (*) → Z (*) Z (*) → 4l, to constrain deviations of the Higgs couplings....     

Searching for a light Higgs boson

The Lindé-Weinberg bound [1] on the mass of the Higgs boson does not apply if one of the fermions of the standard model is very massive [2] or in non-standard models with multiple Higgs particles [1]. We consider both the standard model and a common extension thereof to two or more Higgs doublets. If the Higgs responsible for lepton masses is very light, one reliable method for indirectly detecting it would be a more careful measurement of g − 2 for the muon. More direct is the search for Higgs particles detected in association with τ pairs in existing or defunct e⁺e⁻ colliders operating well below the Z mass. We analyze both methods in detail, and find that data from several existing colliders could eliminate large portions of parameter space - or, perhaps, find the Higgs boson.     

Higgs boson production and weak boson structure

The influence of the QCD structure of the weak bosons on the Higgs boson production ine-p scattering is studied. The energy and Higgs boson mass dependence of the cross-section, following from the new contributions, is calculated. Work supported by the Polish State Committee for Scientifić Research (grant No. 2 P03B 081 09) and the Volkswagen-Stiftung     

漫谈希格斯粒子

希格斯玻色子发现于2012年,是粒子物理学研究中的一件划时代的大事。它在粒子物理的“标准模型”中起关键性作用,通过神秘的对称性破缺机制给基本粒子带来质量,和高深莫测的量子真空息息相关,也被认为在宇宙演化的极早期起重要作用。在希格斯玻色子发现十周年之际,文章将从科普视角出发,描绘希格斯玻色子的理论背景、粒子特性、实验探测、研究现状和展望,揭开希格斯玻色子的神秘面纱,理解它的过去、现在和未来。