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

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

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

Learning from tau appearance

The study of numu->nutau oscillation and the explicit observation of the nutau through the identification of the final-state tau lepton ("direct appearance search") represent the most straightforward test of the oscillation phenomenon. It is, nonetheless, the most challenging from the experimental point of view. In this paper we discuss the current empirical evidence for direct appearance of tau neutrinos at the atmospheric scale and the perspectives for the next few years, up to the completion of the CNGS physics programme. We investigate the relevance of this specific oscillation channel to gain insight into neutrino physics within the standard three-family framework. Finally, we discuss the opportunities offered by precision studies of numu->nutau transitions in the occurrence of more exotic scenarios emerging from additional sterile neutrinos or non-standard interactions.Comment: 26 pages, 7 figures, to appear in NJ

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

A side-by-side comparison of Daya Bay antineutrino detectors

The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle $\theta_{13}$ with a sensitivity better than 0.01 in the parameter sin$^22\theta_{13}$ at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties exceed requirements.Comment: 24 pages, 36 figure