259 research outputs found
Neutrinos Have Mass - So What?
In this brief review, I discuss the new physics unveiled by neutrino
oscillation experiments over the past several years, and discuss several
attempts at understanding the mechanism behind neutrino masses and lepton
mixing. It is fair to say that, while significant theoretical progress has been
made, we are yet to construct a coherent picture that naturally explains
non-zero, yet tiny, neutrino masses and the newly revealed, puzzling patterns
of lepton mixing. I discuss what the challenges are, and point to the fact that
more experimental input (from both neutrino and non-neutrino experiments) is
dearly required - and that new data is expected to reveal, in the next several
years, new information. Finally, I draw attention to the fact that neutrinos
may have only just begun to reshape fundamental physics, given the fact that we
are still to explain the LSND anomaly and because the neutrino oscillation
phenomenon is ultimately sensitive to very small new-physics effects.Comment: invited brief review, 15 pages, 1 eps figure, typo corrected,
reference adde
A Survey of Lepton Number Violation Via Effective Operators
We survey 129 lepton number violating effective operators, consistent with
the minimal Standard Model gauge group and particle content, of mass dimension
up to and including eleven. Upon requiring that each one radiatively generates
the observed neutrino masses, we extract an associated characteristic cutoff
energy scale which we use to calculate other observable manifestations of these
operators for a number of current and future experimental probes, concentrating
on lepton number violating phenomena. These include searches for neutrinoless
double-beta decay and rare meson, lepton, and gauge boson decays. We also
consider searches at hadron/lepton collider facilities in anticipation of the
LHC and the future ILC. We find that some operators are already disfavored by
current data, while more are ripe to be probed by next-generation experiments.
We also find that our current understanding of lepton mixing disfavors a subset
of higher dimensional operators. While neutrinoless double-beta decay is the
most promising signature of lepton number violation for the majority of
operators, a handful is best probed by other means. We argue that a combination
of constraints from various independent experimental sources will help to
pinpoint the ``correct'' model of neutrino mass, or at least aid in narrowing
down the set of possibilities.Comment: 34 pages, 10 eps figures, 1 tabl
On The Decaying-Sterile Neutrino Solution to the Electron (Anti)Neutrino Appearance Anomalies
We explore the hypothesis that the unexplained data from LSND and MiniBooNE
are evidence for a new, heavy neutrino mass-eigenstate that mixes with the
muon-type neutrino and decays into an electron-type neutrino and a new, very
light scalar particle. We consider two different decay scenarios, one with
Majorana neutrinos, one with Dirac neutrinos; both fit the data equally well.
We find a reasonable, albeit not excellent, fit to the data of MiniBooNE and
LSND. The decaying-sterile-neutrino hypothesis, however, cleanly evades
constraints from disappearance searches and precision measurements of leptonic
meson decays, as long as ~keV. The SBN
program at Fermilab should be able to definitively test the
decaying-sterile-neutrino hypothesis.Comment: This version v2 has been accepted for publication in JHEP. The
changes from previous version are: inclusion of the data from KARMEN in the
analysis, a new subsection about the sensitivity of SBN to nonzero decay
effects, an new appendix describing the details of MiniBooNE analysis,
additional references and some other minor change
Isolamento e confirmação da antocianina majoritåria da flor de jambo vermelho por CLAE-ESI-EM/EM.
Desenvolvimento de método por CLUE-EM-EM para detecção de adulterantes em café.
Food: the tree that sustains life. 468
Estudo da estabilidade das antocianinas majoritĂĄrias do fruto do jambo vermelho (Syzygium malaccense L. Merryl & Perry).
O objetivo deste estudo Ă© avaliar a estabilidade das antocianinas majoritĂĄrias de um produto em pĂł, obtido a partir de um processo simples e de baixo custo, da casca do jambo vermelho
Seasonal Variations of the 7Be Solar Neutrino Flux
Measuring the 7Be solar neutrino flux is crucial towards solving the solar
neutrino puzzle. The Borexino experiment, and possibly the KamLAND experiment,
will be capable of studying the 7Be neutrinos in the near future. We discuss
(1) how the seasonal variation of the Borexino and KamLAND data can be used to
measure the 7Be solar neutrino flux in a background independent way and (2) how
anomalous seasonal variations might be used to discover vacuum neutrino
oscillations, independent of the solar model and the measurement of the
background. In particular, we find that, after three years of Borexino or
KamLAND running, vacuum neutrino oscillations can be either established or
excluded for almost all values of (sin^2 2 theta, Delta m^2) preferred by the
Homestake, GALLEX, SAGE, and Super-Kamiokande data. We also discuss how well
seasonal variations of the data can be used to measure (sin^2 2 theta, Delta
m^2) in the case of vacuum oscillations.Comment: 39 pages, 13 figures, uses psfig. Now the impact of the MSW effect on
vacuum oscillations taken into account. Conclusions unchanged. References
adde
Analytical description of quasivacuum oscillations of solar neutrinos
We propose a simple prescription to calculate the solar neutrino survival
probability P_{ee} in the quasivacuum oscillation (QVO) regime. Such
prescription is obtained by matching perturbative and exact analytical results,
which effectively take into account the density distribution in the Sun as
provided by the standard solar model. The resulting analytical recipe for the
calculation of P_{ee} is shown to reach its highest accuracy |\Delta P_{ee}| <
2.6 x 10^{-2} in the whole QVO range) when the familiar prescription of
choosing the solar density scale parameter r_0 at the
Mikheyev-Smirnov-Wolfenstein (MSW) resonance point is replaced by a new one,
namely, when r_0 is chosen at the point of ``maximal violation of
adiabaticity'' (MVA) along the neutrino trajectory in the Sun. The MVA
prescription admits a smooth transition from the QVO regime to the MSW
transition one. We discuss in detail the phase acquired by neutrinos in the
Sun, and show that it might be of relevance for the studies of relatively short
timescale variations of the fluxes of the solar \nu lines in the future
real-time solar neutrino experiments. Finally, we elucidate the role of matter
effects in the convective zone of the Sun.Comment: 25 pages (RevTeX) + 11 figures (postscript
The Oscillation Probability of GeV Solar Neutrinos of All Active Species
In this paper, I address the oscillation probability of O(GeV) neutrinos of
all active flavours produced inside the Sun and detected at the Earth. Flavours
other than electron-type neutrinos may be produced, for example, by the
annihilation of WIMPs which may be trapped inside the Sun. In the GeV energy
regime, matter effects are important both for the ``1-3'' system and the
``1-2'' system, and for different neutrino mass hierarchies. A numerical scan
of the multidimensional three-flavour parameter space is performed,
``inspired'' by the current experimental situation. One important result is
that, in the three-flavour oscillation case, P{alpha,beta} is different from
P{beta,alpha} for a significant portion of the parameter space, even if there
is no CP-violating phase in the MNS matrix. Furthermore, P{mu,mu} has a
significantly different behaviour from P{tau,tau}, which may affect
expectations for the number of events detected at large neutrino telescopes.Comment: 38 pages, 10 figure
- âŠ