18,829 research outputs found
Single Hadron Production in Deep Inelastic Scattering
The NLO-QCD correction to single hadron production in deep inelastic
scattering is calculated. We require the final state meson to carry a
non-vanishing transversal momentum, thus being sensitive to perturbative QCD
effects. Factorization allows us to convolute the hard scattering process with
parton densities and fragmentation functions. The predictions are directly
comparable to experimental results at the HERA collider at DESY. The results
are sensitive to the gluon density in the proton and allow us to test
universality of fragmentation functions.Comment: Proceedings of Ringberg New Trends in HERA Physics Workshop,
Sept.28-Oct.3, 200
Towards testing a two-Higgs-doublet model with maximal CP symmetry at the LHC: construction of a Monte Carlo event generator
A Monte Carlo event generator is constructed for a two-Higgs-doublet model
with maximal CP symmetry, the MCPM. The model contains five physical Higgs
bosons; the , behaving similarly to the standard-model Higgs boson, two
extra neutral bosons and , and a charged pair . The special
feature of the MCPM is that, concerning the Yukawa couplings, the bosons ,
and couple directly only to the second generation fermions but
with strengths given by the third-generation-fermion masses. Our event
generator allows the simulation of the Drell-Yan-type production processes of
, and in proton-proton collisions at LHC energies. Also the
subsequent leptonic decays of these bosons into the , and channels are studied as well as the dominant
background processes. We estimate the integrated luminosities needed in
collisions at center-of-mass energies of 8 TeV and 14 TeV for significant
observations of the Higgs bosons , and in these muonic
channels
Pseudo-Majoron as Light Mediator of Singlet Scalar Dark Matter
In the singlet-triplet majoron model of neutrino mass, lepton number is
spontaneously broken. If it is also softly broken, then a naturally light
pseudoscalar particle exists. It may then act as a light mediator for
a real singlet scalar with odd dark parity. It is itself unstable, but
decays dominantly to two neutrinos through its triplet scalar component,
thereby not disturbing the cosmic microwave background (CMB). It also mixes
with the standard-model Higgs boson only in one loop, thereby not contributing
significantly to the elastic scattering of off nuclei in dark-matter
direct-search experiments.Comment: 10 page
Constraints on the NMSSM from the oblique parameters
Electroweak precision measurements, encoded in the oblique parameters, give
strong constraints on physics beyond the Standard Model. The oblique parameters
S, T, U (V, W, X) are calculated in the next-to-minimal supersymmetric model
(NMSSM). We outline the calculation of the oblique parameters in terms of
one-loop gauge-boson selfenergies and find sensitive restrictions for the NMSSM
parameter space.Comment: 11 pages, 7 figures, 1 tabl
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