646 research outputs found
A Short Travel for Neutrinos in Large Extra Dimensions
Neutrino oscillations successfully explain the flavor transitions observed in
neutrinos produced in natural sources like the center of the sun and the earth
atmosphere, and also from man-made sources like reactors and accelerators.
These oscillations are driven by two mass-squared differences, solar and
atmospheric, at the sub-eV scale. However, longstanding anomalies at
short-baselines might imply the existence of new oscillation frequencies at the
eV-scale and the possibility of this sterile state(s) to mix with the three
active neutrinos. One of the many future neutrino programs that are expected to
provide a final word on this issue is the Short-Baseline Neutrino Program (SBN)
at FERMILAB. In this letter, we consider a specific model of Large Extra
Dimensions (LED) which provides interesting signatures of oscillation of extra
sterile states. We started re-creating sensitivity analyses for sterile
neutrinos in the 3+1 scenario, previously done by the SBN collaboration, by
simulating neutrino events in the three SBN detectors from both muon neutrino
disappearance and electron neutrino appearance. Then, we implemented neutrino
oscillations as predicted in the LED model and also we have performed
sensitivity analysis to the LED parameters. Finally, we studied the SBN power
of discriminating between the two models, the 3+1 and the LED. We have found
that SBN is sensitive to the oscillations predicted in the LED model and have
the potential to constrain the LED parameter space better than any other
oscillation experiment, for . In case SBN observes a
departure from the three active neutrino framework, it also has the power of
discriminating between sterile oscillations predicted in the 3+1 framework and
the LED ones.Comment: 21 pages, 6 figures, 2 table
Neutrino oscillations refitted
Here we update our previous global fit of neutrino oscillations by including
the recent results which have appeared since the Neutrino-2012 conference.
These include the measurements of reactor anti-neutrino disappearance reported
by Daya Bay and RENO, together with latest T2K and MINOS data including both
disappearance and appearance channels. We also include the revised results from
the third solar phase of Super-Kamiokande, SK-III, as well as new solar results
from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred
global determination of the atmospheric angle is consistent with
maximal mixing. We also determine the impact of the new data upon all the other
neutrino oscillation parameters with emphasis on the increasing sensitivity to
the CP phase, thanks to the interplay between accelerator and reactor data. In
the appendix we present the updated results obtained after the inclusion of new
reactor data presented at the Neutrino 2014 conference. We discuss their impact
on the global neutrino analysis.Comment: 13 pages, 5 figures, 2 tables. An appendix providing updated results
after Neutrino-2014 Conference is added. Matches published version in
Physical Review
Global status of neutrino oscillation parameters after Neutrino-2012
Here we update the global fit of neutrino oscillations in arXiv:1103.0734 and
arXiv:1108.1376 including the recent measurements of reactor antineutrino
disappearance reported by the Double Chooz, Daya Bay and RENO experiments,
together with latest MINOS and T2K appearance and disappearance results, as
presented at the Neutrino-2012 conference. We find that the preferred global
fit value of is quite large: for
normal and inverted neutrino mass ordering, with now excluded
at more than 10. The impact of the new measurements over
the other neutrino oscillation parameters is discussed as well as the role of
the new long-baseline neutrino data and the atmospheric neutrino analysis in
the determination of a non-maximal atmospheric angle .Comment: Note added, matches published version in Physical Review
Lepton flavor violation and non-unitary lepton mixing in low-scale type-I seesaw
Within low-scale seesaw mechanisms, such as the inverse and linear seesaw,
one expects (i) potentially large lepton flavor violation (LFV) and (ii)
sizeable non-standard neutrino interactions (NSI). We consider the interplay
between the magnitude of non-unitarity effects in the lepton mixing matrix, and
the constraints that follow from LFV searches in the laboratory. We find that
NSI parameters can be sizeable, up to percent level in some cases, while LFV
rates, such as that for \mu -> e \gamma, lie within current limits, including
the recent one set by the MEG collaboration. As a result the upcoming long
baseline neutrino experiments offer a window of opportunity for complementary
LFV and weak universality tests.Comment: 14 pages, 14 composite figures and 1 table. v2: minor changes,
references added. Accepted for publication in JHE
On the description of non-unitary neutrino mixing
Neutrino oscillations are well established and the relevant parameters
determined with good precision, except for the CP phase, in terms of a unitary
lepton mixing matrix. Seesaw extensions of the Standard Model predict unitarity
deviations due to the admixture of heavy isosinglet neutrinos. We provide a
complete description of the unitarity and universality deviations in the light
neutrino sector. Neutrino oscillation experiments involving electron or muon
neutrinos and anti-neutrinos are fully described in terms of just three new
real parameters and a new CP phase, in addition to the ones describing
oscillations with unitary mixing. Using this formalism we describe the
implications of non-unitarity for neutrino oscillations and summarize the
model-independent constraints on heavy neutrino couplings that arise from
current experiments.Comment: 28 pages, 8 figures, typos corrected, modified bounds on
non-unitarity parameters, new figs 3 and
A short travel for neutrinos in large extra dimensions
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICONeutrino oscillations successfully explain the flavor transitions observed in neutrinos produced in natural sources like the center of the sun and the earth atmosphere, and also from man-made sources like reactors and accelerators. These oscillations are driven by two mass-squared differences, solar and atmospheric, at the sub-eV scale. However, longstanding anomalies at short-baselines might imply the existence of new oscillation frequencies at the eV-scale and the possibility of this sterile state(s) to mix with the three active neutrinos. One of the many future neutrino programs that are expected to provide a final word on this issue is the Short-Baseline Neutrino Program (SBN) at FERMILAB. In this letter, we consider a specific model of Large Extra Dimensions (LED) which provides interesting signatures of oscillation of extra sterile states. We started re-creating sensitivity analyses for sterile neutrinos in the 3+1 scenario, previously done by the SBN collaboration, by simulating neutrino events in the three SBN detectors from both muon neutrino disappearance and electron neutrino appearance. Then, we implemented neutrino oscillations as predicted in the LED model and also we have performed sensitivity analysis to the LED parameters. Finally, we studied the SBN power of discriminating between the two models, the 3+1 and the LED. We have found that SBN is sensitive to the oscillations predicted in the LED model and have the potential to constrain the LED parameter space better than any other oscillation experiment for m1 D < 0.1 eV. In case SBN observes a departure from the three active neutrino framework, it also has the power of discriminating between sterile oscillations predicted in the 3+1 framework and the LED ones.11121FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2014/19164-62016/00272-92016/08308-22017/12904-22017/01749-6307269/2013-2304715/2016-
Status of neutrino oscillations 2018: first hint for normal mass ordering and improved CP sensitivity
We present a new global fit of neutrino oscillation parameters within the
simplest three-neutrino picture, including new data which appeared since our
previous analysis~\cite{Forero:2014bxa}. In this update we include new
long-baseline neutrino data involving the antineutrino channel in T2K, as well
as new data in the neutrino channel, data from NOA, as well as new reactor
data, such as the Daya Bay 1230 days electron antineutrino disappearance
spectrum data and the 1500 live days prompt spectrum from RENO, as well as new
Double Chooz data. We also include atmospheric neutrino data from the IceCube
DeepCore and ANTARES neutrino telescopes and from Super-Kamiokande. Finally, we
also update our solar oscillation analysis by including the 2055-day day/night
spectrum from the fourth phase of the Super-Kamiokande experiment. With the new
data we find a preference for the atmospheric angle in the upper octant for
both neutrino mass orderings, with maximal mixing allowed at for normal (inverted) ordering. We also obtain a strong
preference for values of the CP phase in the range ,
excluding values close to at more than 4. More remarkably, our
global analysis shows for the first time hints in favour of the normal mass
ordering over the inverted one at more than 3. We discuss in detail the
origin of the mass ordering, CP violation and octant sensitivities, analyzing
the interplay among the different neutrino data samples.Comment: Updated neutrino oscillation analysis using the most recent results
from T2K, NOA, RENO and Super-Kamiokande. 17 pages, 8 figures, 1 tabl
Two-parameter neutrino mass matrices with two texture zeros
We reanalyse Majorana-neutrino mass matrices M_nu with two texture zeros, by
searching for viable hybrid textures in which the non-zero matrix elements of
M_nu have simple ratios. Referring to the classification scheme of Frampton,
Glashow and Marfatia, we find that the mass matrix denoted by A1 allows the
ratios (M_nu)_{mu mu} : (Mnu)_{tau tau} = 1:1 and (M_nu)_{e tau} : (Mnu)_{mu
tau} = 1:2. There are analogous ratios for texture A2. With these two hybrid
textures, one obtains, for instance, good agreement with the data if one
computes the three mixing angles in terms of the experimentally determined
mass-squared differences Delta m^2_21 and Delta m^2_31. We could not find
viable hybrid textures based on mass matrices different from those of cases A1
and A2.Comment: 10 pages, no figures, minor changes, some references adde
Electrically controlled waveguide polariton laser
Exciton-polaritons are mixed light-matter particles offering a versatile
solid state platform to study many-body physical effects. In this work we
demonstrate an electrically controlled polariton laser, in a compact,
easy-to-fabricate and integrable configuration, based on a semiconductor
waveguide. Interestingly, we show that polariton lasing can be achieved in a
system without a global minimum in the polariton energy-momentum dispersion.
The surface cavity modes for the laser emission are obtained by adding couples
of specifically designed diffraction gratings on top of the planar waveguide,
forming an in-plane Fabry-Perot cavity. It is thanks to the waveguide geometry,
that we can apply a transverse electric field in order to finely tune the laser
energy and quality factor of the cavity modes. Remarkably, we exploit the
system sensitivity to the applied electric field to achieve an electrically
controlled population of coherent polaritons. The precise control that can be
reached with the manipulation of the grating properties and of the electric
field provides strong advantages to this device in terms of miniaturization and
integrability, two main features for the future development of coherent sources
from polaritonic technologies.Comment: 11 pages, 5 figures. Supplementary: 6 pages, 7 figure
The Glial Regenerative Response to Central Nervous System Injury Is Enabled by Pros-Notch and Pros-NFκB Feedback
Organisms are structurally robust, as cells accommodate changes preserving structural integrity and function. The molecular mechanisms underlying structural robustness and plasticity are poorly understood, but can be investigated by probing how cells respond to injury. Injury to the CNS induces proliferation of enwrapping glia, leading to axonal re-enwrapment and partial functional recovery. This glial regenerative response is found across species, and may reflect a common underlying genetic mechanism. Here, we show that injury to the Drosophila larval CNS induces glial proliferation, and we uncover a gene network controlling this response. It consists of the mutual maintenance between the cell cycle inhibitor Prospero (Pros) and the cell cycle activators Notch and NFκB. Together they maintain glia in the brink of dividing, they enable glial proliferation following injury, and subsequently they exert negative feedback on cell division restoring cell cycle arrest. Pros also promotes glial differentiation, resolving vacuolization, enabling debris clearance and axonal enwrapment. Disruption of this gene network prevents repair and induces tumourigenesis. Using wound area measurements across genotypes and time-lapse recordings we show that when glial proliferation and glial differentiation are abolished, both the size of the glial wound and neuropile vacuolization increase. When glial proliferation and differentiation are enabled, glial wound size decreases and injury-induced apoptosis and vacuolization are prevented. The uncovered gene network promotes regeneration of the glial lesion and neuropile repair. In the unharmed animal, it is most likely a homeostatic mechanism for structural robustness. This gene network may be of relevance to mammalian glia to promote repair upon CNS injury or disease
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