Oscillations, Neutrino Masses and Scales of New Physics

We show that all the available experimental information involving neutrinos can be accounted for within the framework of already existing models where neutrinos have zero mass at tree level, but obtain a small Dirac mass by radiative corrections.Comment: 10 pages, 3 postscript figures (eps

CP Violation with Three Oscillating Neutrino Flavours

We explore the prospects of observing leptonic CP violation in a neutrino factory in the context of a scenario with three strongly oscillating neutrinos able to account for the solar, the atmospheric and the LSND results. We address also the problems related with the fake asymmetries induced by the experimental device and by the presence of matter.Comment: 12 pages, 4 postscript figures (eps), to appear in Phys. Lett.

Neutrino Physics

The Standard Model has been incredibly successful in predicting the outcome of almost all the experiments done up so far. In it, neutrinos are mass-less. However, in recent years we have accumulated evidence pointing to tiny masses for the neutrinos (as compared to the charged leptons). These masses allow neutrinos to change their flavour and oscillate. In these lectures I review the properties of neutrinos in and beyond the Standard Model.Comment: 19 pages, contribution to the 2012 European School of High-Energy Physics, La Pommeraye, Anjou, France, 06-19 Jun 2012, edited by C. Grojean and M. Mulders. arXiv admin note: text overlap with arXiv:hep-ph/0506165 by other author

Neutrinos: Fast & Curious

The Standard Model has been effective way beyond expectations in foreseeing the result of almost all the experimental tests done up so far. In it, neutrinos are massless. Nonetheless, in recent years we have collected solid proofs indicating little but non zero masses for the neutrinos (when contrasted with those of the charged leptons). These masses permit neutrinos to change their flavor and oscillate, indeed a unique treat. In these lectures, I discuss the properties and the amazing potential of neutrinos in and beyond the Standard Model.Comment: 22 pages, contribution to the 2016 European School of High-Energy Physics, Skeikampen, Norway , 15 - 28 June 2016, to appear as a CERN Yellow Report. arXiv admin note: substantial text overlap with arXiv:1504.0703

On the Effective Mass of the Electron Neutrino in Beta Decay

In the presence of mixing between massive neutrino states, the distortion of the electron spectrum in beta decay is, in general, a function of several masses and mixing angles. For $3\nu$-schemes which describe the solar and atmospheric neutrino data, this distortion can be described by a single effective mass, under certain conditions. In the literature, two different definitions for the effective mass have been suggested. We show that for quasi-degenerate mass schemes (with an overall mass scale $m$ and splitting $\Delta m^2$) the two definitions coincide up to $(\Delta m^2)^2/m^4$ corrections. We consider the impact of different effective masses on the integral energy spectrum. We show that the spectrum with a single mass can be used also to fit the data in the case of $4\nu$-schemes motivated, in particular, by the LSND results. In this case the accuracy of the mass determination turns out to be better than $(10 - 15)$.Comment: 15 pages, Version to appear in Phys. Lett.

Neutrinos that violate CPT, and the experiments that love them

Recently we proposed a framework for explaining the observed evidence for neutrino oscillations without enlarging the neutrino sector, by introducing CPT violating Dirac masses for the neutrinos. In this paper we continue the exploration of the phenomenology of CPT violation in the neutrino sector. We show that our CPT violating model fits the existing SuperKamiokande data at least as well as the standard atmospheric neutrino oscillation models. We discuss the challenge of measuring CP violation in a neutrino sector that also violates CPT. We point out that the proposed off-axis extension of MINOS looks especially promising in this regard. Finally, we describe a method to compute CPT violating neutrino effects by mocking them up with analog matter effects.Comment: 17 pages, 3 eps figure

Quintessence, inflation and baryogenesis from a single pseudo-Nambu-Goldstone boson

We exhibit a model in which a single pseudo-Nambu-Goldstone boson explains dark energy, inflation and baryogenesis. The model predicts correlated signals in future collider experiments, WIMP searches, proton decay experiments, dark energy probes, and the PLANCK satellite CMB measurements.Comment: 16 pages, 3 color figure

Tau neutrinos from muon storage rings

Charged tau leptons emerging in a long baseline experiment with a muon storage ring and a far-away detector will positively establish neutrino oscillations. We study the conversion of $\nu_\mu$ ($\bar{\nu}_\mu$) and of $\bar{\nu}_e$ ($\nu_e$) to $\nu_\tau$ or $\bar{\nu}_\tau$ for neutrinos from a 20 GeV muon storage ring, within the strong mixing scheme and on the basis of the squared mass differences which are compatible with all reported neutrino anomalies, including the LSND data. In contrast to other solutions which ignore the Los Alamos anomaly, we find charged tau production rates which should be measurable in a realistic set up. As a consequence, determining the complete mass spectrum of neutrinos as well as all three mixing angles seems within reach. Matter effects are discussed thoroughly but are found to be small in this situation.Comment: 11 pages, 5 postscript figures (eps

MINOS and CPT-violating neutrinos

We review the status of CPT violation in the neutrino sector. Apart from LSND, current data favors three flavors of light stable neutrinos and antineutrinos, with both halves of the spectrum having one smaller mass splitting and one larger mass splitting. Oscillation data for the smaller splitting is consistent with CPT. For the larger splitting, current data favor an antineutrino mass-squared splitting that is an order of magnitude larger than the corresponding neutrino splitting, with the corresponding mixing angle less-than-maximal. This CPT-violating spectrum is driven by recent results from MINOS, but is consistent with other experiments if we ignore LSND. We describe an analysis technique which, together with MINOS running optimized for muon antineutrinos, should be able to conclusively confirm the CPT-violating spectrum proposed here, with as little as three times the current data set. If confirmed, the CPT-violating neutrino mass-squared difference would be an order of magnitude less than the current most-stringent upper bound on CPT violation for quarks and charged leptons.Comment: 18 pages, title change, version to appear in Physical Review