504 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
Anarchy and Hierarchy
We advocate a new approach to study models of fermion masses and mixings,
namely anarchy proposed in hep-ph/9911341. In this approach, we scan the O(1)
coefficients randomly. We argue that this is the correct approach when the
fundamental theory is sufficiently complicated. Assuming there is no physical
distinction among three generations of neutrinos, the probability distributions
in MNS mixing angles can be predicted independent of the choice of the measure.
This is because the mixing angles are distributed according to the Haar measure
of the Lie groups whose elements diagonalize the mass matrices. The
near-maximal mixings, as observed in the atmospheric neutrino data and as
required in the LMA solution to the solar neutrino problem, are highly
probable. A small hierarchy between the Delta m^2 for the atmospheric and the
solar neutrinos is obtained very easily; the complex seesaw case gives a
hierarchy of a factor of 20 as the most probable one, even though this
conclusion is more measure-dependent. U_{e3} has to be just below the current
limit from the CHOOZ experiment. The CP-violating parameter sin delta is
preferred to be maximal. We present a simple SU(5)-like extension of anarchy to
the charged-lepton and quark sectors which works well phenomenologically.Comment: 26 page
Comparação dos modelos digitais de elevação gerados com dados SRTM e cartas IBGE na escala 1:250.000 na região da Bacia do Camanducaia no Estado de São Paulo.
O estudo comparou os MDEs, os mapas de declividade e os mapas hipsomĂ©tricos produzidos pela SRTM com aqueles gerados pelas cartas do IBGE. A ĂĄrea estudada integra a bacia do Camanducaia, que limita-se como Estado de SĂŁo Paulo a leste e JaguariĂșna a oeste, abrangendo Holambra, JaguariĂșna, Santo AntĂŽnio de Posse, Pedreira, Amparo, Serra Negra, Monte Alegre do Sul, Socorro, Pinhalzinho e Pedra Bela
On the complementarity of Hyper-K and LBNF
The next generation of long-baseline experiments is being designed to make a
substantial step in the precision of measurements of neutrino-oscillation
probabilities. Two qualitatively different proposals, Hyper-K and LBNF, are
being considered for approval. This document outlines the complimentarity
between Hyper-K and LBNF.Comment: 5 pager
Initial report from the ICFA Neutrino Panel
In July 2013 ICFA established the Neutrino Panel with the mandate "To promote
international cooperation in the development of the accelerator-based
neutrino-oscillation program and to promote international collaboration in the
development a neutrino factory as a future intense source of neutrinos for
particle physics experiments". This, the Panel's Initial Report, presents the
conclusions drawn by the Panel from three regional "Town Meetings" that took
place between November 2013 and February 2014.
After a brief introduction and a short summary of the status of the knowledge
of the oscillation parameters, the report summarises the approved programme and
identifies opportunities for the development of the field. In its conclusions,
the Panel recognises that to maximise the discovery potential of the
accelerator-based neutrino-oscillation programme it will be essential to
exploit the infrastructures that exist at CERN, FNAL and J-PARC and the
expertise and resources that reside in laboratories and institutes around the
world. Therefore, in its second year, the Panel will consult with the
accelerator-based neutrino-oscillation community and its stakeholders to:
develop a road-map for the future accelerator-based neutrino-oscillation
programme that exploits the ambitions articulated at CERN, FNAL and J-PARC and
includes the programme of measurement and test-beam exposure necessary to
ensure the programme is able to realise its potential; develop a proposal for a
coordinated "Neutrino RD" programme, the accelerator and detector R&D programme
required to underpin the next generation of experiments; and to explore the
opportunities for the international collaboration necessary to realise the
Neutrino Factory.Comment: ICFA Neutrino Panel 2014(01
Adaptação de um mĂ©todo por cromatografia lĂquida de alta eficiĂȘncia para anĂĄlise de antocianinas em suco de açaĂ (Euterpe oleraceae Mart.).
bitstream/item/74935/1/pub-143.pd
MeV sterile neutrinos in low reheating temperature cosmological scenarios
It is commonly assumed that the cosmological and astrophysical bounds on the
mixings of sterile with active neutrinos are much more stringent than those
obtained from laboratory measurements. We point out that in scenarios with a
very low reheating temperature T_RH << 100 MeV at the end of (the last episode
of) inflation or entropy creation, the abundance of sterile neutrinos becomes
largely suppressed with respect to that obtained within the standard framework.
Thus, in this case cosmological bounds become much less stringent than usually
assumed, allowing sterile neutrinos to be ``visible'' in future experiments.
Here, we concentrate on massive (mostly sterile) neutrinos heavier than 1 MeV.Comment: 14 pp, 7 fig
- âŠ