6,996 research outputs found
Neutrinoless double beta decay with and without Majoron-like boson emission in a 3-3-1 model
We consider the contributions to the neutrinoless double beta decays in a
electroweak model. We show that for a range of the
parameters in the model there are diagrams involving vector-vector-scalar and
trilinear scalar couplings which can be potentially as contributing as the
light massive Majorana neutrino exchange one. We use these contributions to
obtain constraints upon some mass scales of the model, like the masses of the
new charged vector and scalar bosons. We also consider briefly the decay in
which besides the two electrons a Majoron-like boson is emitted.Comment: Revtex, 10 pages and 8 eps figures. Extended version to be published
in Physical Review
Realizing the supersymmetric inverse seesaw model in the framework of R-parity violation
If, on one hand, the inverse seesaw is the paradigm of TeV scale seesaw
mechanism, on the other it is a challenge to find scenarios capable of
realizing it. In this work we propose a scenario, based on the framework of
R-parity violation, that realizes minimally the supersymmetric inverse seesaw
mechanism. In it the energy scale parameters involved in the mechanism are
recognized as the vacuum expectation values of the scalars that compose the
singlet superfields and . We develop also the scalar sector
of the model and show that the Higgs mass receives a new tree-level
contribution that, when combined with the standard contribution plus loop
correction, is capable of attaining GeV without resort to heavy stops.Comment: Minor modification of the text. Final version to be published in PL
Using Radium isotopes to evaluate the mixing timeline and relative age of waters in a leaky coastal lagoon
The Ria Formosa wetland system is classified as a leaky coastal lagoon and covers
approximately 100 km2 of the South of Portugal, with roughly 50% being intertidal. Its
hinterland is set in an arid region and on a coastal plain subject to intensive agriculture since the
50’s. In spite of high exchange coefficients with the coastal ocean (50 and 75% at neap and
spring tides, respectively) and the annual total potential freshwater discharge from the hinterland
a fraction of the daily tidal prism, worrying signs of eutrophication have been detected during the
past couple of decades. These include fish- and clam-kill episodes, increased occurrence of
nuisance algal blooms and substitution of native sea grass communities by macroalgae.
Notwithstanding its critical importance for the evaluation of pollutant exposure period, the
literature includes a wide range of estimates for the ‘residence time’ of waters within the lagoon
(16 hours to 11 days, with an the apparent consensus falling within the 1-2 day interval) and this
point is a clear obstacle for a correct environmental risk assessment, including management of
the system. This lack of clarity is due in our view to two main factors: i) the lack of proper
physical definition of the term ‘residence time’, with its consequent misuse and misapplication in
context, a misconception that is unfortunately too common within the environmental community,
and different concepts in the application of transport time scales ii) the geomorphological and
hydraulic complexity of the system.. As part of ongoing research evaluating the role of
Submarine Groundwater Discharge (SGD) as a loading vector for nutrients (especially Nitrate)
into the lagoon, we use the radium quartet in combination with remote sensing and isotope
mixing models to develop and discuss a mixing timeline for the system, We conclude that the
average, whole-system residence time of waters within the lagoon is at least 4 days
Five-Dimensional QED, Muon Pair Production and Correction to the Coulomb Potential
We consider QED in five dimensions in a configuration where matter is
localized on a 3-brane while foton propagates in the bulk. The idea is to
investigate the effects of the Kaluza-Klein modes of the photon in the
relativistic regime, but in low energy, and in the nonrelativistic regime. In
the relativistic regime, we calculate the cross section for the reaction . We compare our theoretical result with a precise
measurement of this cross section at GeV. As result, we
extract a lower bound on the size of the extra dimension. In the
nonrelativistic regime, we derive the contribution for the Coulomb potential
due to the whole tower of the Kaluza-Klein excited modes of the photon. We use
the modified potential to calculate the Rutherford scattering differential
cross section.Comment: minor changes, three new refs. added, to appear in IJMP
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