7,988 research outputs found
Fine structure of beta decay endpoint spectrum
We note that the fine structure at the endpoint region of the beta decay
spectrum is now essentially known using neutrino oscillation data, if the mass
of one neutrino is specified. This may help to identify the effects of nonzero
neutrino masses in future experiments. An exact treatment of phase space
kinematics is used. This work is independent of theoretical models. Additional
restrictions due to the assumption of a so-called "complementary ansatz" for
the neutrino mass matrix are also discussed.Comment: 9 pages, 8 figure
Are small neutrino masses unveiling the missing mass problem of the Universe?
We present a scenario in which a remarkably simple relation linking dark
matter properties and neutrino masses naturally emerges. This framework points
towards a low energy theory where the neutrino mass originates from the
existence of a light scalar dark matter particle in the MeV mass range. A very
surprising aspect of this scenario is that the required MeV dark matter is one
of the favoured candidates to explain the mysterious emission of 511 keV
photons in the centre of our galaxy. A possible interpretation of these
findings is that dark matter is the stepping stone of a theory beyond the
standard model instead of being an embarrassing relic whose energy density must
be accounted for in any successful model building.Comment: 4pages, 2 figures. Two paragraphs have been added. One for the
complex case; the other one for the UV completio
Spin-wave spectrum of copper metaborate in the commensurate phase 10K<T<21K
We have investigated the spin-wave spectrum of copper metaborate,
CuBO, by means of inelastic neutron scattering in the commensurate
magnetic phase. We have found two branches of spin-wave excitations associated
with the two magnetic sublattices Cu(A) and Cu(B), respectively. In the
temperature regime , where only the Cu(A) magnetic moments
are ordered, the interaction between the two sublattices is found to be
negligible. With this approximation we have determined the `easy plane'
exchange parameters of the Cu(A) subsystem within standard spin-wave theory.Comment: 4 figure
Internal kinematics of isolated modelled disk galaxies
We present a systematic investigation of rotation curves (RCs) of fully
hydrodynamically simulated galaxies, including cooling, star formation with
associated feedback and galactic winds. Applying two commonly used fitting
formulae to characterize the RCs, we investigate systematic effects on the
shape of RCs both by observational constraints and internal properties of the
galaxies. We mainly focus on effects that occur in measurements of intermediate
and high redshift galaxies. We find that RC parameters are affected by the
observational setup, like slit misalignment or the spatial resolution and also
depend on the evolution of a galaxy. Therefore, a direct comparison of
quantities derived from measured RCs with predictions of semi-analytic models
is difficult. The virial velocity V_c, which is usually calculated and used by
semi-analytic models can differ significantly from fit parameters like V_max or
V_opt inferred from RCs. We find that V_c is usually lower than typical
characteristic velocities derived from RCs. V_max alone is in general not a
robust estimator for the virial mass.Comment: 9 pages, 15 figures, accepted for publication in A&
Prospects for measuring coherent neutrino-nucleus elastic scattering at a stopped-pion neutrino source
Rates of coherent neutrino-nucleus elastic scattering at a high-intensity
stopped-pion neutrino source in various detector materials (relevant for novel
low-threshold detectors) are calculated. Sensitivity of a coherent
neutrino-nucleus elastic scattering experiment to new physics is also explored.Comment: 9 pages, 14 figures; minor modifications for publicatio
Target space duality and moduli stabilization in String Gas Cosmology
Motivated by string gas cosmology, we investigate the stability of moduli
fields coming from compactifications of string gas on torus with background
flux. It was previously claimed that moduli are stabilized only at a single
fixed point in moduli space, a self-dual point of T-duality with vanishing
flux. Here, we show that there exist other stable fixed points on moduli space
with non-vanishing flux. We also discuss the more general target space
dualities associated with these fixed points.Comment: 12 pages, 1 figur
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