73 research outputs found
Constraints on the axion-electron coupling for solar axions produced by Compton process and bremsstrahlung
The search for solar axions produced by Compton () and bremsstrahlung-like () processes has
been performed. The axion flux in the both cases depends on the axion-electron
coupling constant. The resonant excitation of low-lying nuclear level of
was looked for: Tm Tm
Tm (8.41 keV). The Si(Li) detector and
Tm target installed inside the low-background setup were used to detect
8.41 keV -rays. As a result, a new model independent restriction on the
axion-electron and the axion-nucleon couplings was obtained:
. In model of hadronic
axion this restriction corresponds to the upper limit on the axion-electron
coupling and on the axion mass eV (90%
c.l.). The limits on axion mass are 105 eV and 1.3 keV for
DFSZ- and KSVZ-axion models, correspondingly (90% c.l.).Comment: 7 pages, 4 figure
Neutrino masses and the scalar sector of a B-L extension of the standard model
We consider an electroweak model based on the gauge symmetry SU(2)_L X
U(1)_Y' X U(1)_B-L which has right-handed neutrinos with different exotic B-L
quantum numbers. Because of this particular feature we are able to write Yukawa
terms, and right-handed neutrino mass terms, with scalar fields that can
develop vacuum expectation values belonging to different energy scales. We make
a detailed study of the scalar and the Yukawa neutrino sectors to show that
this model is compatible with the observed solar and atmospheric neutrino mass
scales and the tribimaximal mixing matrix.We also show that there are dark
matter candidates if a Z_2 symmetry is included.Comment: 23 pages, 2 tables, version to be published in Phys. Rev.
Light Sterile Neutrinos in the Supersymmetric U(1)' Models and Axion Models
We propose the minimal supersymmetric sterile neutrino model (MSSNM) where
the sterile neutrino masses are about 1 eV, while the active neutrino masses
and the mixings among the active and sterile neutrinos are generated during
late time phase transition. All the current experimental neutrino data include
the LSND can be explained simultaneously, and the constraints on the sterile
neutrinos from the big bang nucleosynthesis and large scale structure can be
evaded. To realize the MSSNM naturally, we consider the supersymmetric
intermediate-scale U(1)' model, the low energy U(1)' model with a secluded
U(1)'-breaking sector, and the DFSZ and KSVZ axion models. In these models, the
problem can be solved elegantly, and the 1 eV sterile neutrino masses can
be generated via high-dimensional operators. For the low energy U(1)' model
with a secluded U(1)'-breaking sector, we also present a scenario in which the
masses and mixings for the active and sterile neutrinos are all generated
during late time phase transition.Comment: RevTex4, 19 pages, References adde
Phase transition in a supersymmetric axion model
In a supersymmetric axion model where the scale for both supersymmetry
breaking and Peccei-Quinn symmetry breaking is around GeV, we find
that there is a reasonable parameter space for a strongly first order phase
transition at the scale.Comment: 5 pages, 1 figur
Hamiltonian approach to the bound state problem in QCD_2
Bosonization of the two-dimensional QCD in the large N_C limit is performed
in the framework of Hamiltonian approach in the Coulomb gauge. The generalized
Bogoliubov transformation is applied to diagonalize the Hamiltonian in the
bosonic sector of the theory, and the composite operators creating/annihilating
bosons are obtained in terms of dressed quark operators. The bound state
equation is reconstructed as a result of the generalized Bogoliubov
transformation, and the form of its massless solution, chiral pion, is found
explicitly. Chiral properties of the theory are discussed.Comment: 9 pages, LaTeX2
Singlet superfield extension of the minimal supersymmetric standard model with Peccei-Quinn symmetry and a light pseudoscalar Higgs boson at the LHC
Motivated by the mu-problem and the axion solution to the strong CP-problem,
we extend the MSSM with one more chiral singlet field . The underlying
PQ-symmetry allows only one more term in the superpotential. The
spectrum of the Higgs system includes a light pseudoscalar (in addition
to the standard CP-even Higgs boson), predominantly decaying to two photons:
. Both Higgs bosons might be in the range accessible to
current LHC experiments.Comment: 5 pages with 3 figure
Neutrino Masses and the Gluino Axion Model
We extend the recently proposed gluino axion model to include neutrino
masses. We discuss how the canonical seesaw model and the Higgs triplet model
may be realized in this framework. In the former case, the heavy singlet
neutrinos are contained in superfields which do not have any vacuum expectation
value, whereas the gluino axion is contained in one which does. We also
construct a specific renormalizable model which realizes the mass scale
relationship , where is the axion decay constant
and is a large effective mass parameter.Comment: 8 pages, no figur
Search for T-violation in K^+ --> pi^0 mu^+ nu and K^+ --> mu^+ nu gamma Decays
The recent progress in search for T-violating transverse muon polarization in
the decays K^+ --> pi^0 mu^+ nu and K^+ --> mu^+ nu gamma in the on-going
experiment E246 at KEK is reported. Future prospects in polarization
measurements are also discussed.Comment: 11 pages, 5 figures, talk at the Conference of Nuclear Physics
Department RAS, 27 November - 1 December 2000, ITEP, Mosco
Nucleon-Nucleon Bremsstrahlung emission of massive Axion
We consider the problem of axion production by bremsstrahlung emission in a
nuclear medium. The usual assumption of a massless axion is replaced by more
general hypotheses, so that we can describe the emission process for axions
with mass up to a few MeV. We point out that in certain physical situations the
contribution from non-zero mass is non-negligible. In particular, in the
mechanism for the production of Gamma Ray Bursts via emission of heavy axions
the axion mass m_a ~ 1MeV is comparable with the temperature of the nuclear
medium and thus can not be disregarded. Looking at our results we find, in
fact, a fairly considerable reduction of the axion luminosity in that
mechanism.Comment: 16 pages, 5 figure
Unificaxion
Dark matter, gauge coupling unification, and the strong CP problem find a
common and simple solution (in the absence of naturalness) within axion models.
We show that such solution, even without specifying the details of the model
implementation, makes testable predictions for the experimentally measurable
axion parameters: the axion mass and its coupling to photons.Comment: 16 pages, 5 figure
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