9,936 research outputs found

### Constraining extra-fermion(s) from the Higgs boson data

First, we study the fit of the Higgs boson rates, based on all the latest
collider data, in the effective framework for any Extra-Fermion(s) [EF]. The
best-fit results are presented in a generic formalism allowing to apply those
for the test of any EF scenario. The variations of the fit with each one of the
five fundamental parameters are described, and, the obtained fits can be better
than in the Standard Model (SM). We show how the determination of the EF
loop-contributions to the Higgs couplings with photons and gluons is relying on
the knowledge of the top and bottom Yukawa couplings (affected by EF mixings);
for determining the latter coupling, the relevance of the investigation of the
Higgs production in association with bottom quarks is emphasized. In the
instructive approximation of a single EF, we find that the constraints from the
fit already turn out to be quite predictive, in both cases of an EF mixed or
not with SM fermions, and especially when combined with the extra-quark
(-lepton) mass bounds from direct EF searches at the LHC (LEP) collider. In the
case of an unmixed extra-quark, non-trivial fit constraints are pointed out on
the Yukawa couplings for masses up to ~200 TeV. In particular, we define the
extra-dysfermiophilia, which is predicted at 68.27% C.L. for any single
extra-quark (independently of its electric charge). Another result is that,
among any components of SM multiplet extensions, the extra-quark with a -7/3
electric charge is the one preferred by the present Higgs fit.Comment: 27 pages, 10 figures. Subsection structure added and Higgs boson
rates updated (in a separate Appendix) after the Moriond 2013 conferenc

### Single chargino production at linear colliders

We study the single chargino production $e^+ e^- \to \tilde \chi^{\pm}
\mu^{\mp}$ at linear colliders which occurs through the \l_{121} R-parity
violating coupling constant. We focus on the final state containing 4 leptons
and some missing energy. The largest background is \susyq and can be reduced
using the initial beam polarization and some cuts based on the specific
kinematics of the single chargino production. Assuming the highest allowed
supersymmetric background, a center of mass energy of $\sqrt s=500GeV$ and a
luminosity of ${\cal L}=500fb^{-1}$, the sensitivities on the \l_{121}
coupling constant obtained from the single chargino production study improve
the low-energy experimental limit over a range of $\Delta m_{\tilde \nu}
\approx 500GeV$ around the sneutrino resonance, and reach values of $\sim
10^{-4}$ at the $\tilde \nu$ pole. The single chargino production also allows
to reconstruct the $\tilde \chi_1^{\pm}$, $\tilde \chi_2^{\pm}$ and $\tilde
\nu$ masses. The initial state radiation plays a fundamental role in this
study.Comment: 24 pages, Latex file. Linear Collider note LC-TH-2000-04

### Dark matter and neutrino masses in the R-parity violating NMSSM

The R-Parity symmetry Violating (RPV) version of the Next-to-Minimal
Supersymmetric Standard Model (NMSSM) is attractive simultaneously with regard
to the so-called mu-problem and the accommodation of three-flavor neutrino data
at tree level. In this context, we show here that if the Lightest
Supersymmetric Particle (LSP) is the gravitino, it possesses a lifetime larger
than the age of the universe since its RPV induced decay channels are
suppressed by the weak gravitational strength. This conclusion holds if one
considers gravitino masses ~ 10^2 GeV like in supergravity scenarios, and is
robust if the lightest pseudoscalar Higgs field is as light as ~ 10 GeV [as may
occur in the NMSSM]. For these models predicting in particular an RPV
neutrino-photino mixing, the gravitino lifetime exceeds the age of the universe
by two orders of magnitude. However, we find that the gravitino cannot
constitute a viable dark matter candidate since its too large RPV decay widths
would then conflict with the flux data of last indirect detection experiments.
The cases of a sneutrino LSP or a neutralino LSP as well as the more promising
gauge-mediated supersymmetry breaking scenario are also discussed. Both the
one-flavor simplification hypothesis and the realistic scenario of three
neutrino flavors are analyzed. We have modified the NMHDECAY program to extend
the neutralino mass matrix to the present framework.Comment: Latex file, 23 pages, 7 figures. References added and discussion on
the indirect detection modifie

### Single superpartner production at Tevatron Run II

We study the single productions of supersymmetric particles at Tevatron Run
II which occur in the $2 \to 2-body$ processes involving R-parity violating
couplings of type \l'_{ijk} L_i Q_j D_k^c. We focus on the single gaugino
productions which receive contributions from the resonant slepton productions.
We first calculate the amplitudes of the single gaugino productions. Then we
perform analyses of the single gaugino productions based on the three charged
leptons and like sign dilepton signatures. These analyses allow to probe
supersymmetric particles masses beyond the present experimental limits, and
many of the \l'_{ijk} coupling constants down to values smaller than the
low-energy bounds. Finally, we show that the studies of the single gaugino
productions offer the opportunity to reconstruct the $\tilde \chi^0_1$, $\tilde
\chi^{\pm}_1$, $\tilde \nu_L$ and $\tilde l^{\pm}_L$ masses with a good
accuracy in a model independent way.Comment: 47 pages, epsfi

### Neutrino Mass Patterns within the See-saw Model from Multi-localization along Extra Dimensions

We study a multi-localization model for charged leptons and neutrinos,
including the possibility of a see-saw mechanism. This framework offers the
opportunity to allow for realistic solutions in a consistent model without
fine-tuning of parameters, even if quarks are also considered. Those solutions
predict that the large Majorana mass eigenvalues for right-handed neutrinos are
of the same order of magnitude, although this almost common mass can span a
large range (bounded from above by $\sim 10^{12}{\rm GeV}$). The model also
predicts Majorana masses between $\sim 10^{-2}{\rm eV}$ and $\sim 5 \
10^{-2}{\rm eV}$for the left-handed neutrinos, both in the normal and inverted
mass hierarchy cases. This mass interval corresponds to sensitivities which are
reachable by proposed neutrinoless double$\beta$decay experiments. The
preferred range for leptonic mixing angle$\theta_{13}$is:$10^{-2} \lesssim
\sin \theta_{13} \lesssim 10^{-1}$, but smaller values are not totally excluded
by the model.Comment: 36 pages, 8 figure

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