1,026 research outputs found
Higgs triplet effects in purely leptonic processes
We consider the effect of complex Higgs triplets on purely leptonic processes
and survey the experimental constraints on the mass and couplings of their
single and double charge members. Present day experiments tolerate values of
the Yukawa couplings of these scalars at the level of the standard electroweak
gauge couplings. We show that the proposed measurement of the ratio
R_{LCD}=\sigma (\nu_{\mu}e)/ [\sigma (\bb\nu_{\mu}e) + \sigma (\nu_e e )]
would allow to explore a large region of the parameter space inaccessible to
the usual ratio R=\sigma (\nu_{\mu}e)/\sigma (\bb\nu_{\mu}e).Comment: 14 pages, LaTeX, Three figures included using uufiles. A postscript
version is available at ftp://ftp.ifae.es/preprint/ft/uabft378.p
Charged Higgs boson contribution to scattering from low to ultrahigh energy in Higgs triplet model
We study the scattering from low to ultrahigh energy in the
framework of Higgs Triplet Model (HTM). We add the contribution of charged
Higgs boson exchange to the total cross section of the scattering. We obtain
the upper bound in this
process from low energy experiment. We show that by using the upper bound
obtained, the charged Higgs contribution can give enhancements to the total
cross section with respect to the SM prediction up to 5.16% at
eV and maximum at and would help to determine the
feasibility experiments to discriminate between SM and HTM at current available
facilities.Comment: 6 pages, 6 figure
Higgs sector and R-parity breaking couplings in models with broken U(1)_B-L gauge symmetry
Four different supersymmetric models based on SU(2)_L X U(1)_R X U(1)_B-L and
SU(2)_L X SU(2)_R X U(1)_B-L gauge symmetry groups are studied. U(1)_B-L
symmetry is broken spontaneously by a vacuum expectation value (VEV) of a
sneutrino field. The right-handed gauge bosons may obtain their mass solely by
sneutrino VEV. The physical charged lepton and neutrino are mixtures of
gauginos, higgsinos and lepton interaction eigenstates. Explicit formulae for
masses and mixings in the physical lepton fields are found. The spontaneous
symmetry breaking mechanism fixes the trilinear R-parity breaking couplings.
Only some special R-parity breaking trilinear couplings are allowed. There is a
potentially large trilinear lepton number breaking coupling - which is unique
to left-right models - that is proportional to the SU(2)_R gauge coupling g_R.
The couplings are parametrized by few mixing angles, making the spontaneous
R-parity breaking a natural ``unification framework'' for R-parity breaking
couplings in SUSYLR models.Comment: 19 pages, no figures, uses REVTeX. To be published in PR
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Search for Doubly-Charged Higgs Bosons at LEP
Doubly-charged Higgs bosons are searched for in e^+e^- collision data
collected with the L3 detector at LEP at centre-of-mass energies up to 209 GeV.
Final states with four leptons are analysed to tag the pair-production of
doubly charged Higgs bosons. No significant excess is found and lower limits at
95% confidence level on the doubly-charged Higgs boson mass are derived. They
vary from 95.5 GeV to 100.2 GeV, depending on the decay mode. Doubly-charged
Higgs bosons which couple to electrons would modify the cross section and
forward-backward asymmetry of the e^+e^- -> e^+e^- process. The measurements of
these quantities do not deviate from the Standard Model expectations and
doubly-charged Higgs bosons with masses up to the order of a TeV are excluded
Search for Doubly-Charged Higgs Boson Production at HERA
A search for the single production of doubly-charged Higgs bosons H^{\pm \pm}
in ep collisions is presented. The signal is searched for via the Higgs decays
into a high mass pair of same charge leptons, one of them being an electron.
The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment
at HERA. No evidence for doubly-charged Higgs production is observed and mass
dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs
boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only
decays into an electron and a muon via a coupling of electromagnetic strength
h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the
H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged
Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3,
masses below 112 GeV are ruled out.Comment: 15 pages, 3 figures, 1 tabl
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
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