Status and perspectives of short baseline studies

The study of flavor changing neutrinos is a very active field of research. I will discuss the status of ongoing and near term experiments investigating neutrino properties at short distances from the source. In the next few years, the Double Chooz, RENO and Daya Bay reactor neutrino experiments will start looking for signatures of a non-zero value of the mixing angle $\theta_{13}$ with much improved sensitivities. The MiniBooNE experiment is investigating the LSND anomaly by looking at both the $\nu_{\mu} \to \nu_{e}$ and $\bar{\nu}_{\mu} \to \bar{\nu}_{e}$ appearance channels. Recent results on cross section measurements will be discussed briefly.Comment: 6 pages, 2 figures, to appear in the proceedings of the 11th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2009), Rome, Italy, 1-5 July 200

The Last Neutrino Mixing angle theta13

Among the still unmeasured neutrino properties, the third neutrino mixing angle, theta13, is likely to be the one we will next find out. In this contribution, first a brief summary of the limits and the preliminary measurements of this angle is given. Second a critical assessment of a widely used formula connecting two- and three-flavor evolution is provided.Comment: Proceedings of "Nuclear Physics in Astrophysics V, April 2011", Eliat, Israe

Neutrino oscillations and uncertainty relations

We show that coherent flavor neutrino states are produced (and detected) due to the momentum-coordinate Heisenberg uncertainty relation. The Mandelstam-Tamm time-energy uncertainty relation requires non-stationary neutrino states for oscillations to happen and determines the time interval (propagation length) which is necessary for that. We compare different approaches to neutrino oscillations which are based on different physical assumptions but lead to the same expression for the neutrino transition probability in standard neutrino oscillation experiments. We show that a Moessbauer neutrino experiment could allow to distinguish different approaches and we present arguments in favor of the 163Ho-163Dy system for such an experiment.Comment: Some small changes in section 2, results unchanged. Added referenc

Contrasting solar and reactor neutrinos with a non-zero value of theta13

When solar neutrino and KamLAND data are analyzed separately one finds that, even though allowed regions of neutrino parameters overlap, the values of $\delta m^2$ and the mixing angle $\theta_{12}$ at the $\chi^2$ minima are different. We show that a non-zero, but small value of the angle $\theta_{13}$ can account for this behavior. From the joint analysis of solar neutrino and KamLAND data we find the best fit value of $\sin^2 2 \theta_{13} = 0.01 ^{-0.01}_{+0.09}$.Comment: 6 pages of LATEX, 5 figure

Time-Energy Uncertainty Relations for Neutrino Oscillation and M\"Ossbauer Neutrino Experiment

Using the Mandelstam-Tamm method we derive time-energy uncertainty relations for neutrino oscillations. We demonstrate that the small energy uncertainty of antineutrinos in a recently considered experiment with recoilless resonant (M\"ossbauer) production and absorption of tritium antineutrinos is in conflict with the energy uncertainty which, according to the time-energy uncertainty relation, is necessary for neutrino oscillations to happen. A M\"ossbauer neutrino experiment could provide a unique possibility to test the applicability of the time-energy uncertainty relation to neutrino oscillations and to reveal the true nature of neutrino oscillations

New measurement of θ13\theta_{13} via neutron capture on hydrogen at Daya Bay

This article reports an improved independent measurement of neutrino mixing angle $\theta_{13}$ at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse $\beta$-decays with the emitted neutron captured by hydrogen, yielding a data-set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced $^9$Li and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded $\sin^22\theta_{13} = 0.071 \pm 0.011$ in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.Comment: 26 pages, 23 figure