Long range neutrino forces in the cosmic relic neutrino background

Neutrinos mediate long range forces among macroscopic bodies in a vacuum. When the bodies are placed in the neutrino cosmic background, these forces are modified. Indeed, at distances long compared to the scale T -1, the relic neutrinos completely screen off the two-neutrino exchange force, whereas for small distances the interaction remains unaffected. ©2000 The American Physical Society.

Neutrino oscillation in Weitzenbock space-time

In the framework of the teleparallel equivalent of general relativity, we obtain the evolution equation of the neutrino oscillation in vacuum. A comparison with the equivalent result of general relativity case, shows that the Dirac equation in Riemann and Weitzenbock space-times is equivalent in the spherical symmetric Schwarzschild space-time, but turns out to be different in the case of the axial symmetry.

New CP violation in neutrino oscillations

Measurements of CP-violating observables in neutrino oscillation experiments have been studied in the literature as a way to determine the CP-violating phase in the mixing matrix for leptons. Here we show that such observables also probe new neutrino interactions in the production or detection processes. Genuine CP violation and fake CP violation due to matter effects are sensitive to the imaginary and real parts of new couplings. The dependence of the CP asymmetry on the source-detector distance is different from the standard one and, in particular, enhanced at short distances. We estimate that future neutrino factories will be able to probe in this way new interactions that are up to four orders of magnitude weaker than the weak interactions. We discuss the possible implications for models of new physics. ©2001 The American Physical Society.

Exploring neutrino mixing with low energy superbeams

We explore the features of neutrino oscillation which are relevant for measurements of the leptonic CP violating phase δ and the sign of Delta;m13 2 in experiments with low-energy conventional superbeams. Toward the goal, we introduce a new powerful tool called the CP trajectory diagram in bi-probability space which allows us to represent pictorially the three effects, the effects of (a) genuine CP violation due to the sin δ term, (6) CP conserving cos δ term, and (c) fake CP violation due to earth matter, separately in a single diagram. By using the diagram, we observe that there is a two-fold ambiguity in the determination of S which is related with the sign of Delta;m13 2. Possible ways of resolving the ambiguity are discussed. In particular, we point out that an in situ simultaneous measurement of δ and the sign of Delta;m13 2 can be carried out at distances of about 700 km, or at the Phase II of the JHF experiment provided that sin δ ·Delta;m13 2 < 0, both with a megaton class water Cherenkov detector.

Probing the LSND mass scale and four neutrino scenarios with a neutrino telescope

We show in this Letter that the observation of the angular distribution of upward-going muons and cascade events induced by atmospheric neutrinos at the TeV energy scale which can be performed by a kilometer-scale neutrino telescope, such as the IceCube detector, can be used to probe a large neutrino mass splitting, |Δm 2| ∼ (0.5-2.0) eV 2, implied by the LSND experiment and discriminate among four neutrino mass schemes. This is due to the fact that such a large mass scale can promote non-negligible v μ → v e, v τ/v μ → v e, v τ conversions at these energies by the MSW effect as well as vacuum oscillation, unlike what is expected if all the neutrino mass splittings are small. © 2003 Elsevier Science B.V. All rights reserved.

Probing neutrino mass with multilepton production at the Tevatron in the simplest R-parity violation model

We analyse the production of multileptons in the simplest supergravity model with bilinear violation of R parity at the Fermilab Tevatron. Despite the small .R-parity violating couplings needed to generate the neutrino masses indicated by current atmospheric neutrino data, the lightest supersymmetric particle is unstable and can decay inside the detector. This leads to a phenomenology quite distinct from that of the R-parity conserving scenario. We quantify by how much the supersymmetric multilepton signals differ from the R-parity conserving expectations, displaying our results in the m0 ⊙ m1/2 plane. We show that the presence of bilinear R-parity violating interactions enhances the supersymmetric multilepton signals over most of the parameter space, specially at moderate and large m0. © SISSA/ISAS 2003.

Search for scalar neutrino superpartners in e+mu final states in p(p)over-bar collisions at root s=1.96 TeV

We report a search for R-parity-violating production and decay of sneutrino particles in the eμ final state with 1.04±0.06fb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider in 2002-2006. Good agreement between the data and the standard model prediction is observed. With no evidence for new physics, we set limits on the R-parity-violating couplings λ311′ and λ312 as a function of the sneutrino mass. © 2008 The American Physical Society.

Absolute neutrino mass from helicity measurements

The possibility to access the absolute neutrino mass scale through the measurement of the wrong helicity contribution of charged leptons is investigated in pion decay. Through this method, one may have access to the same effective mass m 2β extractable from the tritium beta decay experiments for electron neutrinos as well as the analogous effective mass $(m 2nuμ}){eff} for muon neutrinos. In the channel π-→ ē-v̄, the relative probability of producing an antineutrino with left helicity is enhanced if compared with the naive expectation (m ν/2E ν) 2. The possibility to constrain new interactions in the context of two-Higgs-Doublet models is also investigated. © 2009 World Scientific Publishing Company.

Interferência de Fano e uma ligeira flutuação da marca Majorana

Pós-graduação em Ciência dos Materiais - FEIS

Quasi-Dirac neutrinos and solar neutrino data

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fano interference and a slight fluctuation of the Majorana hallmark

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Subtle leakage of a Majorana mode into a quantum dot

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Probing the antisymmetric Fano interference assisted by a Majorana fermion

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Multimessenger search for sources of gravitational waves and high-energy neutrinos: Initial results for LIGO-Virgo and IceCube

We report the results of a multimessenger search for coincident signals from the LIGO and Virgo gravitational-wave observatories and the partially completed IceCube high-energy neutrino detector, including periods of joint operation between 2007-2010. These include parts of the 2005-2007 run and the 2009-2010 run for LIGO-Virgo, and IceCube's observation periods with 22, 59 and 79 strings. We find no significant coincident events, and use the search results to derive upper limits on the rate of joint sources for a range of source emission parameters. For the optimistic assumption of gravitational-wave emission energy of 10(-2) M(circle dot)c(2) at similar to 150 Hz with similar to 60 ms duration, and high-energy neutrino emission of 1051 erg comparable to the isotropic gamma-ray energy of gamma-ray bursts, we limit the source rate below 1.6 x 10(-2) Mpc(-3) yr(-1). We also examine how combining information from gravitational waves and neutrinos will aid discovery in the advanced gravitational-wave detector era.

Os rapazes da Rua Panisperna e os centomila Majorana: os fatos e as versões literária e audiovisual

While a certain novel ponders about the traces left by Ettore Majorana and expounds some theories about the fate of the character mysteriously disappeared, a movie by Gianni Amelio also inspirited by facts goes through another path, of the story of Via Panisperna boys, stressing the enigmatic figure of Ettore Majorana and the exciting episodes surrounding some of the greatest physicists of the world. When Leonardo Sciascia publishes the novel in which he uses the actual fact of Ettore Majorana’s disappearance in order to create what he calls a “philosophical novel of mystery”, the public had already probably forgotten the intriguing events of 1938: the young and bright physicist disappeared, by all accounts, voluntarily, without leaving proofs of his death or reliable evidence of his whereabouts. In 1972, Sciascia learns about mysterious clues by means of Erasmo Recami and considers the motives that could have made Majorana leave Italy and later abandon his life almost in the mode fictionalized by Pirandello.