Results 1 - 10 of 57209
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[en] We study constraints on type-II two-Higgs-doublet models at large tan β from CERN LEP and SLD Z-pole data and from lepton universality violation in W decay. We perform a global fit and find that, in the context of Z decay, the LEP-SLD experimental values for lepton universality violation, Rb, and Ab all somewhat disfavor the model. Contributions from the neutral-Higgs sector can be used to constrain the scalar-pseudoscalar Higgs mass splittings. Contributions from the charged-Higgs sector allow us to constrain the charged-Higgs boson mass. For tan β=100 we obtain the 1σ classical (Bayesian) bounds of mH±≥670 GeV (370 GeV) and 1≥mh0/mA0|α=β=mH0/mA0|α=0≥0.68 (0.64). The 2σ bounds are weak. Currently, the Fermilab Tevatron experimental limits on lepton universality violation in W decay provide no significant constraint on the Higgs sector. (c) 2000 The American Physical Society
[en] It is considered the production of doubly charged Higgs bosons in decays of W2+→ δR++du, W2+→δR++ι-νιR, W2+→ δR++W1-, W2+→δR++h-. Here W1,2± are light and heavy states of charged gauge bosons
[en] The aim of this paper is to clarify the conceptual difference which exists between the interactions of composite bosons and the interactions of elementary bosons. A special focus is made on the physical processes which are missed when composite bosons are replaced by elementary bosons. Although what is here said directly applies to excitons, it is also valid for composite bosons in other fields than semiconductor physics. We, in particular, explain how the two elementary scatterings - Coulomb and Pauli - of our many-body theory for composite excitons, can be extended to a pair of fermions which is not an Hamiltonian eigenstate - as for example a pair of trapped electrons, of current interest in quantum information. (authors)
[en] The observed structure of the electroweak interactions is understood in terms of a spontaneously broken gauge theory. Although we have as yet no experimental indication as to the nature of the phenomenon responsible for symmetry breaking, general theoretical arguments set an upper limit of 1 or 2 TeV on the energy scale at which some manifestation of this phenomenon must occur. This scale defines a target for the effective hard collision energy that should be achieved in the next accelerator facility; the work reported here was aimed at sharpening this requirement by studying the minimal manifestations of electroweak symmetry breaking that can be expected to occur in the TeV energy region if a Higgs particle with m/sub H/ < 1 TeV is not found. While we used the minimal Higgs model as a guide, the results obtained are of far more general validity. Our analysis relied on three tools, briefly discussed. These are: the equivalence at high energies of longitudinally polarized W's and Z's to their scalar counterparts, the Goldstone bosons; the symmetries of the scalar sector; and the vector boson fusion process. 8 refs
[en] The authors apply a simple approximate relativistic amplitude - unitarization generalization of non-relativistic Schroedinger-equation dynamics to the scattering of longitudinal mass-degenerate W and Z gauge bosons. The strong energy dependence of this amplitude near the WW threshold then makes possible a non-perturbative self-consistent non-elementary neutral Higgs scalar bound state (H) just below this threshold. The authors must, however, include a constant term approximating high-energy inelastic effects in addition to H exchange. Everything, including the H mass, can then be determined in terms of the small phenomenological WWH coupling and W mass, which serves to set the energy scale of the problem; this is the same number of arbitrary parameters as in the underlying electroweak theory. The partial-wave amplitude containing the H is then in approximate agreement at zero energy with the one given by the perturbative crossing-symmetric H-pole-only tree-graph amplitude. The authors find unacceptable zero-energy disagreement, however, if, instead of an inelasticity term, they insert a open-quotes subtraction constantclose quotes approximating the effect of high-mass exchange to obtain their H
[en] We present a general formulation for the WW → H and ZZ → H mechanisms of heavy Higgs boson production in hadron colliders. The known results in the effective W approximation are obtained from the quark-parton model limit of the double inelastic scattering configuration. In addition we estimate contributions from the elastic scattering configurations and from αsub(s)-processes of QCD
[en] A search for heavy resonances in final states with a Higgs boson and a vector boson is presented, performed in the data collected with the CMS detector at √s = 13TeV during 2015. The vector boson can be either a Z or W boson decaying leptonically (electrons, muons or neutrinos), whereas the Higgs boson decays hadronically into a couple of b-quarks of high momentum, detected as a single massive jet. The investigated final states consist of two b-quarks and zero, one or two charged leptons. Background shape and normalization are derived through a hybrid data-Monte Carlo method. The search is performed by examining the distribution of the reconstructed mass for a localized excess. Upper limits are derived as a function of the resonance mass and natural width, and are interpreted within the Heavy Vector Triplet theoretical model, as predicted in many scenarios beyond the standard model.
[en] We analyze the one loop corrections to leptonic W and Z decays in an R-parity violating extension to the minimal supersymmetric standard model. We find that lepton universality violation in the Z line-shape variables alone would strengthen the bounds on the magnitudes of the λ' couplings, but a global fit on all data leaves the bounds virtually unchanged at |λ33k'|≤0.42 and |λ23k'|≤0.50 at the 2σ level. Bounds from W decays are less stringent: |λ33k'|≤2.4 at 2σ, as a consequence of the weaker Fermilab experimental bounds on lepton universality violation in W decays. We also point out the potential of constraining R-parity violating couplings from the measurement of the Υ invisible width. (c) 2000 The American Physical Society
[en] We discuss in which sense the so-called regular pseudo-bosons, recently introduced by Trifonov and analyzed in some detail by the author, are related to ordinary bosons. We repeat the same analysis for pseudo-bosons, and analyze the role played by certain intertwining operators, which may be bounded or not.