497 research outputs found
Symmetries, Large Leptonic Mixing and a Fourth Generation
We show that large leptonic mixing occurs most naturally in the framework of
the Sandard Model just by adding a fourth generation. One can then construct a
small discrete symmetry, instead of the large ,
which requires that the neutrino as well as the charged lepton mass matrices be
proportional to a democratic mass matrix, where all entries are
equal to unity. Without considering the see-saw mechanism, or other more
elaborate extensions of the SM, and contrary to the case with only 3
generations, large leptonic mixing is obtained when the symmetry is broken.Comment: 6 pages, ReVTeX, no figure
Detecting matter effects in long baseline experiments
Experiments strongly suggest that the flavour mixing responsible for the
atmospheric neutrino anomaly is very close to being maximal. Thus, it is of
great theoretical as well as experimental importance to measure any possible
deviation from maximality. In this context, we reexamine the effects of matter
interactions in long baseline neutrino oscillation experiments. Contrary to
popular belief, the muon neutrino survival probability is shown to be quite
sensitive to matter effects. Moreover, for moderately long baselines, the
difference between the survival probilities for and is
shown to be large and sensitive to the deviation of from
maximality. Performing a realistic analysis, we demonstrate that a muon-storage
ring -source alongwith an iron calorimeter detector can measure such
deviations. (Contrary to recent claims, this is not so for the NuMI--{\sc
minos} experiment.) We also discuss the possible correlation in measuring
and in such experiment.Comment: 18 pages, LaTe
Fake CPT Violation in Disappearance Neutrino Oscillations
We make an analysis of the fake CPT-violating asymmetries between the
survival probabilities of neutrinos and antineutrinos, induced by the
terrestrial matter effects, in three different scenarios of long-baseline
neutrino oscillation experiments with L=730 km, L=2100 km and L=3200 km. In
particular, the dependence of those asymmetries on the Dirac-type CP-violating
phase of the lepton flavor mixing matrix is examined.Comment: RevTex 8 pages (including 3 PS figures). To be publishe
Exploration of Possible Quantum Gravity Effects with Neutrinos II: Lorentz Violation in Neutrino Propagation
It has been suggested that the interactions of energetic particles with the
foamy structure of space-time thought to be generated by quantum-gravitational
(QG) effects might violate Lorentz invariance, so that they do not propagate at
a universal speed of light. We consider the limits that may be set on a linear
or quadratic violation of Lorentz invariance in the propagation of energetic
neutrinos, v/c=[1 +- (E/M_\nuQG1)] or [1 +- (E/M_\nu QG2}^2], using data from
supernova explosions and the OPERA long-baseline neutrino experiment.Comment: 8 pages, 6 figures, proceedings for invited talk by A.Sakharov at
DISCRETE'08, Valencia, Spain; December 200
Diffuse supernova neutrinos: oscillation effects, stellar cooling and progenitor mass dependence
We estimate the diffuse supernova neutrino background (DSNB) using the recent
progenitor-dependent, long-term supernova simulations from the Basel group and
including neutrino oscillations at several post-bounce times. Assuming
multi-angle matter suppression of collective effects during the accretion
phase, we find that oscillation effects are dominated by the matter-driven MSW
resonances, while neutrino-neutrino collective effects contribute at the 5-10%
level. The impact of the neutrino mass hierarchy, of the time-dependent
neutrino spectra and of the diverse progenitor star population is 10% or less,
small compared to the uncertainty of at least 25% of the normalization of the
supernova rate. Therefore, assuming that the sign of the neutrino mass
hierarchy will be determined within the next decade, the future detection of
the DSNB will deliver approximate information on the MSW-oscillated neutrino
spectra. With a reliable model for neutrino emission, its detection will be a
powerful instrument to provide complementary information on the star formation
rate and for learning about stellar physics.Comment: 19 pages, including 4 figures and 1 table. Clarifying paragraphs
added; results unchanged. Matches published version in JCA
Unity of CP and T Violation in Neutrino Oscillations
In a previous work a simultaneous P- CP[P] and P- T[P] bi-probability plot
was proposed as a useful tool for unified graphical description of CP and T
violation in neutrino oscillation. The ``baseball diamond'' structure of the
plot is understood as a consequence of the approximate CP-CP and the T-CP
relations obeyed by the oscillation probabilities. In this paper, we make a
step forward toward deeper understanding of the unified graphical
representation by showing that these two relations are identical in its
content, suggesting a truly unifying view of CP and T violation in neutrino
oscillations. We suspect that the unity reflects the underlying CPT theorem. We
also present calculation of corrections to the CP-CP and the T-CP relations to
leading order in Delta m^2_{21} / Delta m^2_{31} and s^2_{13}.Comment: 20 references added, version to appear in "Focus Issue on Neutrino
Physics" of New Journal of Physic
Parentsâ Ethnotheories of Maladaptive Behavior in Young Children
Parentsâ culturally influenced belief systems, or ethnotheories, are critical components of childrenâs socialization. Beliefs about childrenâs desirable characteristics motivate specific parenting activities and moderate the effectiveness of childrearing practices. However, relatively little attention has been given to parentsâ ethnotheories of childrenâs undesirable behavior. From a few studies, we know that parents have culturally specific theories about the nature and management of childrenâs maladaptive behavior that motivate their socialization practices. In this review, we identify gaps in the research and suggest that qualitative studies of parentsâ ethnotheories about the nature and management of childrenâs deviant behavior have strong theoretical, empirical, and practical benefits for developmental science.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151344/1/cdep12330.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151344/2/cdep12330_am.pd
Baryogenesis, Electric Dipole Moments and Dark Matter in the MSSM
We study the implications for electroweak baryogenesis (EWB) within the
minimal supersymmetric Standard Model (MSSM) of present and future searches for
the permanent electric dipole moment (EDM) of the electron, for neutralino dark
matter, and for supersymmetric particles at high energy colliders. We show that
there exist regions of the MSSM parameter space that are consistent with both
present two-loop EDM limits and the relic density and that allow for successful
EWB through resonant chargino and neutralino processes at the electroweak phase
transition. We also show that under certain conditions the lightest neutralino
may be simultaneously responsible for both the baryon asymmetry and relic
density. We give present constraints on chargino/neutralino-induced EWB implied
by the flux of energetic neutrinos from the Sun, the prospective constraints
from future neutrino telescopes and ton-sized direct detection experiments, and
the possible signatures at the Large Hadron Collider and International Linear
Collider.Comment: 32 pages, 10 figures; version to appear on JHE
Spectroscopy of -nucleus bound states at GSI and FAIR --- very preliminary results and future prospects ---
The possible existence of \eta'-nucleus bound states has been put forward
through theoretical and experimental studies. It is strongly related to the
\eta' mass at finite density, which is expected to be reduced because of the
interplay between the anomaly and partial restoration of chiral
symmetry. The investigation of the C(p,d) reaction at GSI and FAIR, as well as
an overview of the experimental program at GSI and future plans at FAIR are
discussed.Comment: 7 pages, 3 figures; talk at the International Conference on Exotic
Atoms and Related Topics (EXA2014), Vienna, Austria, 15-19 September 2014. in
Hyperfine Interactions (2015
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