Narrow Results

We review the present status of the QCD corrected cross-sections and kinematic distributions for the production of a Higgs boson in association with bottom quarks at the Fermilab Tevatron and CERN Large Hadron Collider. Results are presented for the Minimal Supersymmetric Standard Model where, for large tan β, these production modes can be greatly enhanced compared to the Standard Model case. The next-to-leading order QCD results are much less sensitive to the renormalization and factorization scales than the lowest order results, but have a significant dependence on the choice of the renormalization scheme for the bottom quark Yukawa coupling. We also investigate the uncertainties coming from the Parton Distribution Functions and find that these uncertainties can be comparable to the uncertainties from the remaining scale dependence of the next-to-leading order results. We present results separately for the different final states depending on the number of bottom quarks identified.

We studied single Higgs boson production in γγ collisions proceeding via the hadronic content of the photon. For SM Higgs masses of current theoretical interest, the resolved photon contributions are non-negligible in precision cross section measurements. We found that production of the heavier Higgs bosons H⁰ and A⁰ of the MSSM can probe regions of the SUSY parameter space that will complement other measurements. Finally, we showed that associated tH^± production in γγ collisions can be used to make an accurate determination of tan β for low and high tan β by precision measurements of the γγ → H^±t + X cross section.

Connes's ideeas provide a framework in which the Higgs fields appear as components of a generalized gauge connection. This leads to theories with predictive power in the Higgs sector (for example, one can show that spontaneous symmetry breaking arises in a natural way). We describe a realization of this formalism where the underlying manifold is a two-sheeted space-time. We show how our particular formulation works for the case of the Standard Model and the Left-Right Symmetric Model.

We present a general formalism based on the framework of noncommutative geometry, suitable to the study of the standard model of electroweak interactions, as well as that of more general gauge theories. Left- and right-handed chiral fields are assigned to two different sheets of space–time (a discretized version of Kaluza–Klein theory). Scalar Higgs fields find themselves treated on the same footing as the gauge fields, resulting in spontaneous symmetry breaking in a natural and predictable way. As a first test, we apply the formalism to the Standard Model, where one can predict the Higgs mass and the top Yukawa coupling. The results obtained for this case are similar with results obtained in alternate formulations. We then study the left–right symmetric model, where we show that this framework imposes interesting constraints on the type and coefficients of terms appearing in the Higgs potential.

A mechanism is discussed to obtain light scalar fields from a spontaneously broken continuous symmetry without explicitly breaking it. If there is a continuous manifold of classical vacua in orbit space, its tangent directions describe classically massless fields that may acquire mass from perturbations of the potential that do not break the symmetry. We consider the simplest possible example, involving a scalar field in the adjoint representation of SU(N). We study the scalar mass spectrum and its renormalization group running at one-loop level including scalar and pseudoscalar Yukawa couplings to a massive Dirac fermion.

Electroweak precision physics is reviewed from the LEP era with implications for Higgs bosons and supersymmetry, together with expectations for the LHC and a future Linear Collider ILC.

We argue that the consistent implementation of the multiple point principle (MPP) in the general nonsupersymmetric two-Higgs doublet model (2HDM) can lead to a set of approximate global custodial symmetries that ensure CP conservation in the Higgs sector and the absence of flavor changing neutral currents (FCNC) in the considered model. In particular, the existence of a large set of degenerate vacua at some high energy scale Λ caused by the MPP can result in approximate U(1) and Z₂ symmetries that suppress FCNC and CP-violating interactions in the 2HDM. We explore the renormalization group (RG) flow of the Yukawa and Higgs couplings within the MPP inspired 2HDM with approximate custodial symmetries and show that the solutions to the RG equations are focused near quasifixed points at low energies if the MPP scale Λ is relatively high. We study the Higgs spectrum and couplings near the quasifixed point at moderate values of tan β and compute a theoretical upper bound on the lightest Higgs boson mass. If Λ ≳ 10¹⁰GeV the lightest CP-even Higgs boson is always lighter than 125 GeV. When the MPP scale is low, the mass of the lightest Higgs particle can reach 180–220 GeV while its coupling to the top quark can be significantly larger than in the SM, resulting in the enhanced production of Higgs bosons at the LHC. Other possible scenarios that appear as a result of the implementation of the MPP in the 2HDM are also discussed.

The charged Higgs production associated with a W^± boson has a smooth cross-section as a function of the charged Higgs mass at muon colliders. The cross-section in minimal supersymmetric standard model (MSSM) is about 25 fb in the range 200 GeV < m_H^± <400 GeV with tan β = 50. This is much larger than the corresponding cross-section at an e⁺e^- collider which reaches a fraction of femtobarn. The observability of this charged Higgs production at a muon collider has been recently studied in an earlier work leading to the result that with 1 ab^-1, a 5σ signal can be observed throughout the aforementioned mass range. In this paper, results of a study based on a general two Higgs doublet model (types II and III) are presented and the cross-section of the charged Higgs production in the most sensitive parameter space is evaluated. It is concluded that the cross-section increases with increasing neutral Higgs boson masses involved in the s-channel diagram and can be as large as several picobarn with tan β = 50. The region of "physical Higgs boson mass" parameter space which could lead to a 5σ signal at 50 fb^-1 is specified.

Recent progress is presented on higher-order calculations for the mass spectrum of Higgs particles in the CP-conserving and CP-violating MSSM, covering diagrammatic two-loop calculations for neutral and charged Higgs bosons as well as all-order resummation of large logarithms arising from the strong and Yukawa coupling sectors.

In this paper the charged Higgs signal through triple or double Higgs production in a two Higgs doublet model (2HDM) type II is studied. The main production process is e⁺e^- →H⁺H^-H⁰ followed by the charged Higgs decay to a pair of τν and the neutral Higgs decay to . The alternative process H⁺W^-H⁰ is also included as a source of charged Higgs signal in the analysis. The focus is on a future e⁺e^- linear collider operating at . The final state under consideration is suitable for electroweak background rejection using the b-tagging tools. It is shown that although the signal cross-section is small, with a reasonable background suppression, high signal significance values are achievable at an integrated luminosity 500 fb^-1 depending on the charged Higgs mass, tan β and the CP-odd neutral Higgs mass. Finally results are quoted in terms of the signal significance for charged Higgs in the mass range 160 < m_H^± < 400 GeV.

In the Minimal Supersymmetric Standard Model (MSSM), the bottom Yukawa coupling of the Higgs boson can considerably deviate from its Standard Model prediction due to nondecoupling effects. We point out that the ratio of the Higgs boson decay branching fraction to a bottom quark pair and that to a W-boson pair from the same production channel is particularly sensitive to large additional MSSM Higgs boson mass regions at future electron–positron colliders. Based on this precision measurement, we explicitly show the indirect discovery reach of the additional Higgs bosons according to planned programs of the International Linear Collider.

Compared to the minimal supersymmetric standard model (MSSM), $\mu$ from $\nu$ Supersymmetric Standard Model ($\mu \nu$SSM) introduces three singlet right-handed neutrino superfields, which lead to the mixing of the Higgs doublets with the sneutrinos. This mixing affects the Standard Model (SM)-like Higgs boson mass. In this work, we separately give the mixing of the CP-even and CP-odd neutral scalar mass matrices with the explicit CP violation, and analyze how the phases impact the SM-like Higgs boson mass and the signal strengths. At the same time, we give the radiative corrections for the Higgs boson mass with effective potential methods.

In this paper, we consider dark spinor and Higgs fields coupled to gravity and calculate their contributions to the energy density and pressure in Friedmann–Robertson–Walker spacetime. We seek solutions of the fields to yield a de Sitter universe and investigate stability properties of the solutions using linear approximation. We discuss the possibility that the inflationary period of our universe can be described by a combination of the dark spinor and Higgs fields.

Mirror universe is a fundamental way to restore parity symmetry in weak interactions. It naturally provides the lightest mirror nucleon as a unique GeV-scale asymmetric dark matter particle candidate. We conjecture that the mirror parity is respected by the fundamental interaction Lagrangian, and its possible soft breaking arises only from non-interaction terms in the gauge-singlet sector. We realize the spontaneous mirror parity violation by minimizing the vacuum Higgs potential, and derive the corresponding Higgs spectrum. We demonstrate that the common origin of CP violation in the visible and mirror neutrino seesaws can generate the right amount of matter and mirror dark matter via leptogenesis. We analyze the direct detections of GeV-scale mirror dark matter by TEXONO and CDEX experiments. We further study the predicted distinctive Higgs signatures at the LHC.

The production cross-sections calculations for the process . Where represent the three neutral Higgs bosons, are calculated through all the allowed modes of interactions. Which are (1296) situations are consider in two different groups of Feynman diagrams are taken into account.

(1) Production of from and Z⁰ propagators exchange (from 1-864 Feynman diagrams).

(2) Production of from propagators and the neutralino is leg (from 865-1296 Feynman diagrams).

where (i, j = 1,2,3, and ℓ = 1,2,3,4)

The values of the cross sections σ are taken as a function of the incident center of mass energy S. The values of the cross-sections have greatest values at S ranges from 3000 to 3400 GeV., and the against cross section is from rang 2.5 × 10^-10-4 × 10^-10, and the best calculations have numbers from 865-1080, where the production mechanisms can be detected in mode when the neutralino is leg from positron.

The cross-section, in electron (e^-) positron (e⁺) collision, are calculated over range of center of mass energy for the process.

i - Production of χ⁰ and H^± when z⁰ and H⁰ are the propagators exchange.

ii - Production of χ⁰ and H^± when χ⁰ is a leg from electron or positron, and γ is the propagator.

iii - Production of χ⁰ and H^± when χ⁰ is a leg from electron and positron, and Z⁰ is the propagator.

iv - Production of χ⁰ and H^± when χ⁰ is a leg from electron or positron, and H⁰ is the propagator.

Where (i, j = 1,2,3, and = 1,2,3,4)

The cross section for each group is calculated according to a carefully selected set of parameters.

These different possible (1155) situations are graphed and tabulated.

The production mechanisms can be detected as:

The twentieth century has thrown up exotic concepts — dark matter, gravity waves, Higgs Bosons, Magnetic Monopoles and so on. The sad truth is that even after several decades, these remain elusive to observation and experiment. Some are now questioning these conjectures. Their verification has become a matter more of hope than conviction. We will examine some alternatives in the light of the above pointing out that, on the other hand, an extra neutrino, recently predicted by the author may have just been discovered.

Recent progress is presented on higher-order calculations for the mass spectrum of Higgs particles in the CP-conserving and CP-violating MSSM, covering diagrammatic two-loop calculations for neutral and charged Higgs bosons as well as all-order resummation of large logarithms arising from the strong and Yukawa coupling sectors.