1,354 research outputs found
Large Neutrino Mixing with Universal Strength of Yukawa Couplings
We analyse, within the framework of universal strength for Yukawa couplings
(USY), various structures for the Dirac and Majorana neutrino mass matrices
giving rise, through the see-saw mechanism, to a degenerate mass spectrum. A
specific USY ansatz is presented for the charged lepton and neutrino effective
mass matrix, leading to quasi-degenerate neutrinos and a leptonic mixing matrix
which provides a large angle solution for both the atmospheric and solar
neutrino problems.Comment: 7 pages, ReVTeX, small comments adde
Out-of-phase oscillation between superfluid and thermal components for a trapped Bose condensate under oscillatory excitation
The vortex nucleation and the emergence of quantum turbulence induced by
oscillating magnetic fields, introduced by Henn E A L, et al. 2009 (Phys. Rev.
A 79, 043619) and Henn E A L, et al. 2009 (Phys. Rev. Lett. 103, 045301), left
a few open questions concerning the basic mechanisms causing those interesting
phenomena. Here, we report the experimental observation of the slosh dynamics
of a magnetically trapped Rb Bose-Einstein condensate (BEC) under the
influence of a time-varying magnetic field. We observed a clear relative
displacement in between the condensed and the thermal fraction center-of-mass.
We have identified this relative counter move as an out-of-phase oscillation
mode, which is able to produce ripples on the condensed/thermal fractions
interface. The out-of-phase mode can be included as a possible mechanism
involved in the vortex nucleation and further evolution when excited by time
dependent magnetic fields.Comment: 5 pages, 5 figures, 25 reference
Large effects on \BsBs mixing by vector-like quarks
We calculate the contributions of the vector-like quark model to \BsBs
mixing, taking into account the constraints from the decay . In
this model the neutral bosons mediate flavor-changing interactions at the tree
level. However, \BsBs mixing is dominated by contributions from the box
diagrams with the top quark and the extra up-type quark. In sizable ranges of
the model parameters, the mixing parameter is much different from the
standard model prediction.Comment: 11 pages, 4 figures, To be published in Phys. Rev.
Right-handed-neutrino Majorana mass at the SUSY GUT scale and the solution of the solar-neutrino problem
In the SUSY GUT scenario, it is natural to assume the right-handed-neutrino
Majorana-mass scale to be GeV. This will in principle lead, by the
seesaw mechanism, to a mass of order . This suggests that the solution of
the solar-neutrino puzzle should be either the MSW effect in
-- oscillations, with , or long-wavelength -- oscillations, with . These solutions require
unexpectedly large mixings of with and ,
respectively. I suggest a variation of the Dimopoulos--Hall--Raby model for the
fermion mass matrices which can accomodate such large mixings.Comment: 10 pages, standard LATEX, no figures, Carnegie-Mellon University
Report CMU-HEP93-27 and DOE-ER/40682-5
A neutrino mass matrix with seesaw mechanism and two-loop mass splitting
We propose a model which uses the seesaw mechanism and the lepton number
to achieve the neutrino mass spectrum and , together with a lepton mixing matrix with .
In this way, we accommodate atmospheric neutrino oscillations. A small mass
splitting is generated by breaking spontaneously and using
Babu's two-loop mechanism. This allows us to incorporate ``just so''
solar-neutrino oscillations with maximal mixing into the model. The resulting
mass matrix has three parameters only, since breaking leads
exclusively to a non-zero matrix element.Comment: 8 pages, Late
Inclusive dileptonic rare B decays with an extra generation of vector-like quarks
We investigate the leading effects of extending the Standard Model of
electroweak interactions by an extra iso-singlet up- and down- type quark pair
on various distributions and total branching ratio of the inclusive B-> X_s l^+
l^- (l =e,\mu) rare B decays. The presence of the extra vector-like down quark
results in the non-unitarity of the extended quark mixing matrix V, which
in turn leads to b-> s FCNC at the tree level proportional to (V^\dagger
V)_{sb}. On the other hand, the effective penguin and box vertex functions are
sensitive to the mass of the extra iso-singlet up quark m_U. The experimental
upper bound on BR(B-> X_s \mu^+ \mu^-) is used to constrain the parameters of
the model. It is shown that the shapes of the differential branching ratio and
forward-backward asymmetry distribution are very sensitive to the value of the
model parameters. We also calculate the CP aymmetry distribution of the
dileptonic decay in the vector-like quark model. It is shown that, for a
typical choice of the model parameters, asymmetries up to around 10% can be
achieved for certain values of the dilepton invariant mass.Comment: 15 pages, 2 figure
Constraining Models of New Physics in Light of Recent Experimental Results on
We study extensions of the Standard Model where the charged current weak
interactions are governed by the CKM matrix and where all tree-level decays are
dominated by their Standard Model contribution. We constrain both analytically
and numerically the ratio and the phase difference between the New Physics and
the Standard Model contributions to the mixing amplitude of the neutral
system using the experimental results on , ,
and . We present new results concerning models with minimal
flavor violation and update the relevant parameter space. We also study the
left-right symmetric model with spontaneously broken CP, probing the viability
of this model in view of the recent results for and other
observables.Comment: 32 pages, including 9 figures, typos and error in fig. 1 corrected,
minor modificiation in the text, conclusions unchanged, to appear in PR
Highly water soluble room temperature superionic liquids of APIs
Fundacao para a Ciencia e a Tecnologia through project (PEst-C/LA0006/2013). The authors also thank Prof. Madalena Dionisio and Dr Natalia Correia for their support with the DSC analyses.Herein a straightforward approach for the enhancement of the water solubility of common antibiotic and NSAID active pharmaceutical ingredients (APIs) is presented. The APIs are converted into ionic liquids (API-ILs) and molten salts by combination with the organic superbases TMG, DBU and DBN. The prepared superionic liquids were characterized by 1H and 13C NMR as well as FTIR spectroscopy and elemental analysis. Most products are amorphous non-polymorphic room temperature ionic liquids with very high solubility in water, which may enhance the bioavailability of the API-ILs in comparison with the parent drugs.authorsversionpublishe
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