Search results for "Higgs"
showing 10 items of 1127 documents
Reconciling Cold Dark Matter with COBE/IRAS Plus Solar and Atmospheric Neutrino Data
1994
We present a model where an unstable MeV Majorana tau \neu can naturally reconcile the cold dark matter model (CDM) with cosmological observations of large and small scale density fluctuations and, simultaneously, with data on solar and atmospheric neutrinos. The solar \neu deficit is explained through long wavelength, so-called {\sl just-so} oscillations involving conversions of \ne into both \nm and a sterile species \ns, while atmospheric \neu data are explained through \nm to \ne conversions. Future long baseline \neu oscillation experiments, as well as some reactor experiments will test this hypothesis. The model is based on the spontaneous violation of a global lepton number symmetry …
Phenomenology of dark matter from A(4) flavor symmetry
2011
We investigate a model in which Dark Matter is stabilized by means of a Z2 parity that results from the same non-abelian discrete flavor symmetry which accounts for the observed pattern of neutrino mixing. In our A4 example the standard model is extended by three extra Higgs doublets and the Z2 parity emerges as a remnant of the spontaneous breaking of A4 after electroweak symmetry breaking. We perform an analysis of the parameter space of the model consistent with electroweak precision tests, collider searches and perturbativity. We determine the regions compatible with the observed relic dark matter density and we present prospects for detection in direct as well as indirect Dark Matter s…
Dark matter as the origin of neutrino mass in the inverse seesaw mechanism
2021
We propose that neutrino masses are "seeded" by a dark sector within the inverse seesaw mechanism. This way we have a new, "hidden", variant of the scotogenic scenario for radiative neutrino masses. We discuss both explicit and dynamical lepton number violation. In addition to invisible Higgs decays with majoron emission, we discuss in detail the pheneomenolgy of dark matter, as well as the novel features associated to charged lepton flavour violation, and neutrino physics.
Present and future searches with e^+e^- colliders for the neutral Higgs bosons of the Minimal Supersymmetric Standard Model -- the complete 1-loop an…
1994
New mass regions unexcluded by direct searches are revealed by an analysis of experimental results from LEP1 using full 1-loop diagrammatic calculations of radiative corrections in the MSSM. Simulations of experimental signal efficiencies and background rejection factors, and full 1-loop calculations are combined to study the sensitivity for neutral Higgs bosons at LEP2 and the NLC. Compared with previous studies based on an Effective Potential Approach, we identify mass regions where the discovery potential depends on the MSSM parameters other than the top and stop masses. We propose our method of interpretation to be adopted by the four LEP experiments for better precision. The possibilit…
Self-consistent variational approach to the minimal left-right symmetric model of electroweak interactions
2006
The problem of mass generation is addressed by a Gaussian variational method for the minimal left-right symmetric model of electroweak interactions. Without any scalar bidoublet, the Gaussian effective potential is shown to have a minimum for a broken symmetry vacuum with a finite expectation value for both the scalar Higgs doublets. The symmetry is broken by the fermionic coupling that destabilizes the symmetric vacuum, yielding a self consistent fermionic mass. In this framework a light Higgs is only compatible with the existence of a new high energy mass scale below 2 TeV.
Invisible Higgs decays and neutrino physics
1993
Abstract A wide class of neutrino physics motivated models are characterized by the spontaneous violation of a global U(1) lepton number symmetry at or below the electroweak scale by an SU(2)⊗U(1) singlet vacuum expectation value 〈 σ 〉 ≲ O(1) TeV. In all these models the main Higgs decay channel is likely to be “invisible”, e.g. h → JJ, where J denotes the associated weakly interacting pseudoscalar Goldstone boson — the majoron. This leads to events with large missing energy that could be observable at LEP and affect the Higgs mass bounds obtained, as well as lead to novel ways to search for Higgs bosons and high-energy supercolliders such as the LHC/SSC.
An effective field theory approach to the electroweak corrections at LEP energies
1999
In the framework of the effective field theory (EFT) we discuss the electroweak (EW) corrections at LEP energies. We obtain the effective Lagrangian in the large m_t limit, and reproduce analytically the dominant EW corrections to the LEP2 processes e+ e- --> gamma Z and e+ e- --> Z Z. To include effects of finite top-quark and Higgs masses, we use the effective Lagrangian at tree level and fit LEP1/SLD observables with four arbitrary parameters, plus alpha_s(m_Z). The EFT approach works remarkably well. Using the effective couplings determined from the fit, and tree-level EFT formulae, we predict the cross sections for e+ e- --> Z Z, gamma Z at a level better than 1%.
A SEARCH FOR PAIR-PRODUCED CHARGED HIGGS BOSONS IN Z0 DECAYS
1990
The utilitarian representation of sport in Rumania, a brake in the development of leisure practice. Since the countries of central Europe entered the liberal sphere influence, the consumptions of possessions and services develop there. We observe a movement of tutellaire and ideological emancipation of the sports organizations, but the practice of popular physical activities delays developing. If, on the ground, we notice the appearance of an structured professionally offer, contrary to all expectations, it does not pull a real increase of consumption. This situation which rises in inferred paradox a cultural interrogation on the previous history of these brakes. Historically, the sport dur…
Seesaw roadmap to neutrino mass and dark matter
2018
We describe the many pathways to generate Majorana and Dirac neutrino mass through generalized dimension-5 operators a la Weinberg. The presence of new scalars beyond the Standard Model Higgs doublet implies new possible field contractions, which are required in the case of Dirac neutrinos. We also notice that, in the Dirac neutrino case, the extra symmetries needed to ensure the Dirac nature of neutrinos can also be made responsible for stability of dark matter.
Combined Tevatron upper limit ongg→H→W+W−and constraints on the Higgs boson mass in fourth-generation fermion models
2010
We combine results from searches by the CDF and D0 collaborations for a standard model Higgs boson (H) in the process gg -> H -> W+W- in p (p) over bar collisions at the Fermilab Tevatron Collider at root s = 1.96 TeV. With 4.8 fb(-1) of integrated luminosity analyzed at CDF and 5.4 fb(-1) at D0, the 95% confidence level upper limit on sigma(gg -> H) x B(H -> W+W-) is 1.75 pb at m(H) = 120 GeV, 0.38 pb at m(H) = 165 GeV, and 0.83 pb at m(H) = 200 GeV. Assuming the presence of a fourth sequential generation of fermions with large masses, we exclude at the 95% confidence level a standard-model-like Higgs boson with a mass between 131 and 204 GeV.