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 $\nu_\mu$ and $\bar\nu_\mu$ is shown to be large and sensitive to the deviation of $|U_{\mu 3}|$ from maximality. Performing a realistic analysis, we demonstrate that a muon-storage ring $\nu$-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 $U_{\mu 3}$ and $U_{e3}$ in such experiment.Comment: 18 pages, LaTe

Oscillation effects on supernova neutrino rates and spectra and detection of the shock breakout in a liquid Argon TPC

A liquid Argon TPC (ICARUS-like) has the ability to detect clean neutrino bursts from type-II supernova collapses. In this paper, we consider for the first time the four possible detectable channels, namely, the elastic scattering on electrons from all neutrino species, $\nu_e$ charged current absorption on $Ar$ with production of excited $K$, $\bar\nu_e$ charged current absorption on $Ar$ with production of excited $Cl$ and neutral current interactions on $Ar$ from all neutrino flavors. We compute the total rates and energy spectra of supernova neutrino events including the effects of the three--flavor neutrino oscillation with matter effects in the propagation in the supernova. Results show a dramatic dependence on the oscillation parameters and in the energy spectrum, especially for charged-current events. The shock breakout phase has also been investigated using recent simulations of the core collapse supernova. We stress the importance of the neutral current signal to decouple supernova from neutrino oscillation physics.Comment: 40 pages, 19 figures, version v2 accepted for publication in JCAP. accepted in JCA

Theoretical Prospects of Neutrinoless Double Beta Decay

The compelling experimental evidences for oscillations of solar and atmospheric neutrinos imply the existence of 3-neutrino mixing in vacuum. We briefly review the phenomenology of 3-neutrino mixing, and the current data on the 3-neutrino mixing parameters. The open questions and the main goals of future research in the field of neutrino mixing and oscillations are outlined. The predictions for the effective Majorana mass || in neutrinoless double beta (bb0nu-) decay in the case of 3-neutrino mixing and massive Majorana neutrinos are reviewed. The physics potential of the experiments, searching for bb0nu-decay and having sensitivity approximately 10 times better than the presently reached, for providing information on the type of the neutrino mass spectrum, on the absolute scale of neutrino masses and on the Majorana CP-violation phases in the PMNS neutrino mixing matrix, is discussed.Comment: 15 pages, 2 postscript figures, LATEX; Invited talk given at the Nobel Symposium (N 129) on Neutrino Physics, August 19 - 24, 2004, Haga Slott, Enkoping, Swede

Neutrino physics overview

Seesaw-type and low-scale models of neutrino masses are reviewed, along with the corresponding structure of the lepton mixing matrix. The status of neutrino oscillation parameters as of June 2006 is given, including recent fluxes, as well as latest SNO, K2K and MINOS results. Some prospects for the next generation of experiments are given. This writeup updates the material presented in my lectures at the Corfu Summer Institute on Elementary Particle Physics in September 2005.Comment: Review based on lectures at the Corfu Summer Institute on Elementary Particle Physics in September 2005. To be published in the Proceeding

Neutrino physics at accelerators

Present and future neutrino experiments at accelerators are mainly concerned with understanding the neutrino oscillation phenomenon and its implications. Here a brief account of neutrino oscillations is given together with a description of the supporting data. Some current and planned accelerator neutrino experiments are also explained.Comment: 23 pages, 24 figures. Talk given at the Corfu Summer Institute on Elementary Particle Physics 200

Leptonic CP Violation and Neutrino Mass Models

We discuss leptonic mixing and CP violation at low and high energies, emphasizing possible connections between leptogenesis and CP violation at low energies, in the context of lepton flavour models. Furthermore we analyse weak basis invariants relevant for leptogenesis and for CP violation at low energies. These invariants have the advantage of providing a simple test of the CP properties of any lepton flavour model.Comment: 26 pages, no figures, submitted to the Focus Issue on `Neutrino Physics` edited by F. Halzen, M. Lindner and A. Suzuki, to be published in New Journal of Physic

Neutrino-2008: Where are we? Where are we going?

Our present knowledge of neutrinos can be summarized in terms of the "standard neutrino scenario". Phenomenology of this scenario as well as attempts to uncover physics behind neutrino mass and mixing are described. Goals of future studies include complete reconstruction of the neutrino mass and flavor spectrum, further test of the standard scenario and search for new physics beyond it. Developments of new experimental techniques may lead to construction of new neutrino detectors from table-top to multi-Megaton scales which will open new horizons in the field. With detection of neutrino bursts from the Galactic supernova and high energy cosmic neutrinos neutrino astrophysics will enter qualitatively new phase. Neutrinos and LHC (and future colliders), neutrino astronomy, neutrino structure of the Universe, and probably, neutrino technologies will be among leading topics of research.Comment: 15 pages, 7 figures, Invited talk at the XXIII International Conference on Neutrino Physics and Astrophysics, Christchurch, New Zealand, May 25 - 31, 200

Evidence for muon neutrino oscillation in an accelerator-based experiment

We present results for muon neutrino oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced muon neutrino beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy dependent disappearance of muon neutrino, which we presume have oscillated to tau neutrino. The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).Comment: 5 pages, 4 figure