1,564 research outputs found
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
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
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
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
On the Convergence of the Milky Way and M31 Kinematics from Cosmological Simulations
The kinematics of the Milky Way (MW) and M31, the dominant galaxies in the
Local Group (LG), can be used to estimate the LG total mass. New results on the
M31 proper motion have recently been used to improve that estimate. Those
results are based on kinematic priors that are sometimes guided and evaluated
using cosmological N-body simulations. However, the kinematic properties of
simulated LG analogues could be biased due to the effective power spectrum
truncation induced by the small size of the parent simulation. Here we explore
the dependence of LG kinematics on the simulation box size to argue that
cosmological simulations need a box size on the order of 1 Gpc in order to
claim convergence on the LG kinematic properties. Using a large enough
simulation, we find M31 tangential and radial velocities relative to the MW to
be in the range km/s and km/s, respectively. This study highlights that LG
kinematics derived from N-body simulations have to be carefully interpreted
taking into account the size of the parent simulation.Comment: 7 pages, 4 figures, Accepted for publication in Ap
Prevalencia de trematodes y factores de riesgo asociados con el ganado lechero en Colombia
This study was conducted to establish the prevalence and identify the risk factors associated with trematode infections in dairy cattle in the Boyacá Highlands, Colombia. Fecal samples collected from 300 randomly selected cattle were examined using a simple sedimentation technique for differential trematodes egg count. The animals were found shedding eggs of three groups of trematodes, namely Fasciola hepatica, Paramphistomum cervi and Cotylophoron cotylophorum. The specific prevalence of this trematodes were 11.6%, 9.3%, and 3.7% respectively. A substantial overlap was observed in the appearance of F. hepatica y P. cervi. The prevalence of the three trematodes identified in this study was significantly associated (p<0.05) with body condition and breed, while the prevalence of Fasciola hepatica and Paramphistomum cervi, was associated with age. The prevalence of the three main trematodes of importance for animal health with a high rate of mixed infection along with a poor body condition, suggests a substantial economic loss incurred due to reduced productivity of livestock in the study area.El estudio se llevó a cabo para establecer la prevalencia e identificar los factores de riesgo asociados con las infecciones por trematodes en ganado lechero de las tierras altas de Boyacá, Colombia. Las muestras fecales recogidas de 300 bovinos seleccionados al azar se examinaron utilizando una técnica de sedimentación simple para el recuento diferencial de huevos de trematodes. En el ganado estudiado fueron encontrados huevos de tres grupos de trematodes, a saber: Fasciola hepatica, Paramphistomum cervi y Cotylophoron cotylophorum. La prevalencia específica para estas tres especies fueron de 11,6%, 9,3% y 3,7% respectivamente. Se observó una superposición importante entre F. hepatica y P. cervi. La prevalencia de los tres trematodes identificados en este estudio se asoció significativamente (p<0,05) con la condición corporal y la raza, mientras que la prevalencia de Fasciola sp y Paramphistomum sp fue asociada con la edad. La prevalencia de los tres principales trematodes de importancia para la salud animal y la alta tasa de infección mixta, junto al deterioro de la condición corporal, determinan una pérdida económica sustancial debida a la reducción de la productividad del ganado en el área estudiada
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
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