368 research outputs found
Hidden top quark decays to charged Higgs scalars at the Tevatron
Charged Higgs scalars light enough to contribute to top quark decays are
possible in various non--minimal Higgs models. We show that such a decay would
be consistent with the current Tevatron data, and will remain hidden until a
larger luminosity can be achieved.Comment: 17 pages, latex, 6 figure
Constraint on the branching ratio of B_c \to tau nu from LEP1 and consequences for R(D(*)) anomaly
Recently there has been interest in the correlation between R(D*) and the
branching ratio (BR) of in models with a charged scalar
H^\pm. Any enhancement of R(D*) by alone (in order to agree with
current data) also enhances ), for which there has been no
direct search at hadron colliders. We show that LEP data taken at the Z peak
requires BR() < 10%, and this constraint is significantly
stronger than the recent constraint BR() < 30% from
considering the lifetime of B_c. In order to respect this new constraint, any
explanation of the R(D) and R(D*) anomaly in terms of alone would
require the future measurements of R(D*) to be even closer to the Standard
Model prediction. A stronger limit on BR() (or its first
measurement) would be obtained if the L3 collaboration used all its data taken
at the Z peak.Comment: 14 pages, 4 figures, a reference and two sentences adde
Dependence of the leptonic decays of H^- on the neutrino mixing angles theta_{13} and theta_{23} in models with neutrinophilic charged scalars
In the Higgs Triplet Model and the neutrinophilic Two-Higgs-Doublet Model the
observed neutrinos obtain mass from a vacuum expectation value which is much
smaller than the vacuum expectation value of the Higgs boson in the Standard
Model. Both models contain a singly charged Higgs boson (H^-) whose Yukawa
coupling is directly related to the neutrino mass (i.e. a "neutrinophilic
charged Higgs"). The partial decay widths of H^- into a charged lepton and a
neutrino (H^- to l^- nu) depend identically on the neutrino masses and mixings
in the two models. We quantify the impact of the recent measurement of
sin^2(2theta_{13}), which plays a crucial role in determining the magnitude of
the branching ratio of H^- to e^- nu for the case of a normal neutrino mass
ordering if the lightest neutrino mass m_0 < 10^{-3} eV. We also discuss the
sizeable dependence of H^- to mu^- nu and H^- to tau^- nu on sin^2(theta_{23}),
which would enable information to be obtained on sin^2(theta_{23}) and the sign
of \Delta m^2_{31} if these decays are measured. Such information would help
neutrino oscillation experiments to determine the CP-violating phase \delta.Comment: 17 pages, 6 figure
Light charged Higgs boson with dominant decay to quarks and its search at LHC and future colliders
The possibility of a light charged Higgs boson that decays
predominantly to quarks ( and/or ) and with a mass in the range 80 GeV
GeV is studied in the context of Three-Higgs-Doublet
Models (3HDMs). At present the Large Hadron Collider (LHC) has little
sensitivity to this scenario, and currently the best constraints are from LEP2
and Tevatron searches. The branching ratio of can be dominant in
two of the five types of 3HDM, and we determine the parameter space where this
occurs. The decay has recently been searched for at the LHC for
the first time, and with increased integrated luminosity one would expect
sensitivity to the region 80 GeV GeV due to the smaller
backgrounds with respect to decays.Comment: 25 pages, 17 figure
B_s decays at Belle
We report recent results obtained with the Belle detector using a 23.6
fb^{-1} data sample collected on the Y(5S) resonance at the KEKB asymmetric
energy e^+ e^- collider. Inclusive semileptonic B_s^0 -> X^+ l^- \nu decays are
studied for the first time and the branching fraction is measured. Combining
the electron and muon channels, we obtain Bf(B_s^0 -> X^+ l^- \nu) = (10.2 \pm
0.8 \pm 0.9)%. Also, the radiative penguin decay B_s^0 -> \phi \gamma is
observed for the first time, and an improved upper limit for the decay B_s^0
\to \gamma \gamma is obtained.Comment: Proceedings of the EPS/HEP 2007 Conference, Manchester, England, July
2007 (on behalf of the Belle collaboration), 3 pages, 2 figure
Probing Majorana Phases and Neutrino Mass Spectrum in the Higgs Triplet Model at the LHC
Doubly charged Higgs bosons (H^++) are a distinctive signature of the Higgs
Triplet Model of neutrino mass generation. If H^++ is relatively light
(m_{H^++} < 400GeV) it will be produced copiously at the LHC, which could
enable precise measurements of the branching ratios of the decay channels H^++
to l_i l_j. Such branching ratios are determined solely by the neutrino mass
matrix which allows the model to be tested at the LHC. We quantify the
dependence of the leptonic branching ratios on the absolute neutrino mass and
Majorana phases, and present the permitted values for the channels ee, emu and
mumu. It is shown that precise measurements of these three branching ratios are
sufficient to extract information on the neutrino mass spectrum and probe the
presence of CP violation from Majorana phases.Comment: 1+19 pages, 22 figures, typos corrected, references added, version to
appear in Phys. Rev.
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