2,114 research outputs found

### Leptoquark Contribution to the Higgs Boson Production at the LHC Collider

In this report we study how a light-scalar leptoquark could affect the Higgs
boson production cross-section at the LHC collider. We construct the most
general renormalizable and gauge invariant effective Lagrangian involving the
standard model particles and a scalar, isoscalar leptoquark, \eta.
The total cross-section for pp -> H+X is then calculated for different values
of the unknown parameters \lambda_eta, m_eta and m_H.(Here \lambda_eta is the
coupling associated with the Higgs-leptoquark interaction.)
We find that if \lambda_eta is moderately large and m_eta is around a few
hundred GeV, then the cross-section is significantly larger than the standard
model value.Comment: 9 pages, 4 postscript figure

### Limits on excited tau leptons masses from leptonic tau decays

We study the effects induced by excited leptons on the leptonic tau decay at
one loop level. Using a general effective lagrangian approach to describe the
couplings of the excited leptons, we compute their contributions to the
leptonic decays and use the current experimental values of the branching ratios
to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.

### Production of Doubly Charged Higgs Bosons at Linear e-e- Colliders

Production of doubly charged Higgs bosons via the s-channel process e-e- ->
H-- -> l-l- at future linear collider energies is studied by taking into
account initial state radiation (ISR) and beamstrahlung (ISR + BS), final state
radiation (FSR) and detector smearing effects. The discovery bounds of lepton
flavour conserving and violating couplings are obtained for doubly charged
Higgs bosons. It is found that future linear colliders with centre of mass
energies and will be able to probe the doubly charged Higgs bosons with
diagonal couplings down to 10^-4 and 10^-3, respectively.Comment: 22 pages, 12 figures, 4 table

### Non-thermal Leptogenesis and a Prediction of Inflaton Mass in a Supersymmetric SO(10) Model

The gravitino problem gives a severe constraint on the thermal leptogenesis
scenario. This problem leads us to consider some alternatives to it if we try
to keep the gravitino mass around the weak scale $m_{3/2} \sim 100$ GeV. We
consider, in this paper, the non-thermal leptogenesis scenario in the framework
of a minimal supersymmetric SO(10) model. Even if we start with the same
minimal SO(10) model, we have different predictions for low-energy
phenomenologies dependent on the types of seesaw mechanism. This is the case
for leptogenesis: it is shown that the type-I see-saw model gives a consistent
scenario for the non-thermal leptogenesis but not for type-II. The predicted
inflaton mass needed to produce the observed baryon asymmetry of the universe
is found to be $M_I \sim 5 \times 10^{11}$ GeV for the reheating temperature
$T_R = 10^6$ GeV.Comment: 9 pages, 2 figures; the version to appear in JCA

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