Recent Refinements in Higgs Physics

2017

The charged Higgs boson is an inevitable particle in supersymmetric models, both in the minimal version and in extensions. It is also a particle, which may have different decay channels depending on the scalar representations in the model, and thus it may help in identifying the model. In this talk I will consider the simplest singlet and triplet extensions of the minimal supersymmetric standard model, and in particular, describe some smoking gun signals of charged Higgs at the LHC collider. I will also comment the charged scalars in a supersymmetric left-right model.

Progress in Particle and Nuclear Physics, 2003

Precision electroweak data presently favors a weakly-coupled Higgs sector as the mechanism responsible for electroweak symmetry breaking. Low-energy supersymmetry provides a natural framework for weakly-coupled elementary scalars. In this review, we summarize the theoretical properties of the Standard Model (SM) Higgs boson and the Higgs sector of the minimal supersymmetric extension of the Standard Model (MSSM). We then survey the phenomenology of the SM and MSSM Higgs bosons at the Tevatron, LHC and a future e + e − linear collider. We focus on the Higgs discovery potential of present and future colliders and stress the importance of precision measurements of Higgs boson properties.

AIP Conference Proceedings, 2008

Old and new ideas regarding Higgs physics are reviewed. We first summarize the quadratic divergence / hierarchy problem which strongly suggests that the SM Higgs sector will be supplemented by new physics at high scales. We next consider means for delaying the hierarchy problem of the SM Higgs sector to unexpectedly high scales. We then outline the properties of the most ideal Higgs boson. The main advantages of a supersymmetric solution to the high scale problems are summarized and the reasons for preferring the next-to-minimal supersymmetric model over the minimal supersymmetric model in order to achieve an ideal Higgs are emphasized. This leads us to the strongly motivated scenario in which there is a Higgs h with SM-like WW, ZZ couplings and m h ∼ 100 GeV that decays via h → aa with m a < 2m b , where m a > 2m τ is preferred, implying a → τ + τ -. The means for detecting an h → aa → 4τ signal are then discussed. Some final cautionary and concluding remarks are given.

Particles, Strings and Cosmology (PASCOS 99), 2000

It is shown that in the Standard Model, the property of charge quantization holds for a Higgs with arbitrary isospin and hypercharge. These defining quantum numbers of the Higgs remain unconstrained while the whole basic and fundamental structure of the Standard Model remains intact. Hence it is shown that the Higgs cannot be a physical particle. Higgs is the underlying 'vacuum' over which the whole edifice of the Standard Model stands. Also on most general grounds it is established here that as per the Standard Model there is no electric charge above the electro-weak phase transition temperature. Hence there was no electric charge present in the Early Universe. The Superstring Theories are flawed in as much as they are incompatible with this requirement.

2005

List of Figures xiii List of Tables xiv Preface xv Acknowledgements xx Cirriculum Vitae xxi x 4.5 The transverse momentum distributions for the MSSM pseudoscalar Higgs boson for tan β = 30, 40, 50 and M A 0 = 120 GeV/c 2 at the Tevatron including the top and bottom quark loops. The top, middle, and bottom lines in the top graph are the curves for tan β = 50, 40, 30 respectively. Below is the fraction of the process that comes from each of the different channels. The curves at p t = 250 GeV/c from top to bottom are the qg, gg,

Advanced Series on Directions in High Energy Physics, 1997

The Higgs sector of the Minimal Supersymmetric Model (MSSM) is a CPconserving two-Higgs doublet model that depends, at tree-level, on two Higgs sector parameters. In order to accurately determine the phenomenological implications of this model, one must include the effects of radiative corrections. The leading contributions to the one-loop radiative corrections are exhibited; large logarithms are resummed by the renormalization group method. Implications for Higgs phenomenology are briefly discussed.

Physical Review D, 2010

We consider supersymmetric models that include particles beyond the Minimal Supersymmetric Standard Model (MSSM) with masses in the TeV range, and that couple significantly to the MSSM Higgs sector. We perform a model-independent analysis of the spectrum and couplings of the MSSM Higgs fields, based on an effective theory of the MSSM degrees of freedom. The tree-level mass of the lightest CP-even state can easily be above the LEP bound of 114 GeV, thus allowing for a relatively light spectrum of superpartners, restricted only by direct searches. The Higgs spectrum and couplings can be significantly modified compared to the MSSM ones, often allowing for interesting new decay modes. We also observe that the gluon fusion production cross section of the SM-like Higgs can be enhanced with respect to both the Standard Model and the MSSM.

Nuclear Physics B, 1995

We compute the upper bound on the mass of the lightest Higgs boson in the Minimal Supersymmetric Standard Model in a model-independent way, including leading (one-loop) and next-to-leading order (two-loop) radiative corrections. We find that (contrary to some recent claims) the two-loop corrections are negative with respect to the one-loop result and relatively small ( < ∼ 3%). After defining physical (pole) top quark mass M t , by including QCD self-energies, and physical Higgs mass M H , by including the electroweak self-energies Π M 2 H − Π(0), we obtain the upper limit on M H as a function of supersymmetric parameters. We include as supersymmetric parameters the scale of supersymmetry breaking M S , the value of tan β and the mixing between stops X t = A t + µ cot β (which is responsible for the threshold correction on the Higgs quartic coupling). Our results do not depend on further details of the supersymmetric model. In particular, for M S ≤ 1 TeV, maximal threshold effect X 2 t = 6M 2 S and any value of tan β, we find M H ≤ 140 GeV for M t ≤ 190 GeV. In the particular scenario where the top is in its infrared fixed point we find M H ≤ 86 GeV for M t = 170 GeV.

2017

This thesis presents the phenomenological analysis of the charged Higgs sector in 3-Higgs Doublet Models (3HDMs) and that of heavy Higgs bosons in Composite 2-Higgs Doublet Models (C2HDMs). In the first chapter, the main properties of five types of 3HDMs are summarised. In addition, the constraints from the measurements of the B &gt; Xsy decay rate on the parameter space of 3HDMs are considered at the next-to-leading order in QCD and then limits from direct searches for H 1 and H2 at colliders are discussed. In the other chapters, we move on to the investigation of a C2HDM framework based on the spontaneous breakdown of a global symmetry SO(6) → SO(4) × SO(2) at the compositeness scale f. The motivations and the main properties of it are summarised. By requiring C2HDMs to full perturbative unitarity at energies, we obtain constraints on its parameters. We also study the Large Hadron Collider (LHC) phenomenology of C2HDMs of various Yukawa types by concentrating on the modications fr...

2000

It is shown that in the Standard Model, the property of charge quantization holds for a Higgs with arbitrary isospin and hypercharge. These defining quantum numbers of the Higgs remain unconstrained while the whole basic and fundamental structure of the Standard Model remains intact. Hence it is shown that the Higgs cannot be a physical particle. Higgs is the underlying 'vacuum' over which the whole edifice of the Standard Model stands.