Precision on leptonic mixing parameters at future neutrino oscillation experiments

We perform a comparison of the different future neutrino oscillation experiments based on the achievable precision in the determination of the fundamental parameters theta_{13} and the CP phase, delta, assuming that theta_{13} is in the range indicated by the recent Daya Bay measurement. We study the non-trivial dependence of the error on delta on its true value. When matter effects are small, the largest error is found at the points where CP violation is maximal, and the smallest at the CP conserving points. The situation is different when matter effects are sizable. As a result of this effect, the comparison of the physics reach of different experiments on the basis of the CP discovery potential, as usually done, can be misleading. We have compared various proposed super-beam, beta-beam and neutrino factory setups on the basis of the relative precision of theta_{13} and the error on delta. Neutrino factories, both high-energy or low-energy, outperform alternative beam technologies. An ultimate precision on theta_{13} below 3% and an error on delta of < 7^{\circ} at 1 sigma (1 d.o.f.) can be obtained at a neutrino factory.Comment: Minor changes, matches version accepted in JHEP. 30 pages, 9 figure

Requirements for a New Detector at the South Pole Receiving an Accelerator Neutrino Beam

There are recent considerations to increase the photomultiplier density in the IceCube detector array beyond that of DeepCore, which will lead to a lower detection threshold and a huge fiducial mass for the neutrino detection. This initiative is known as "Phased IceCube Next Generation Upgrade" (PINGU). We discuss the possibility to send a neutrino beam from one of the major accelerator laboratories in the Northern hemisphere to such a detector. Such an experiment would be unique in the sense that it would be the only neutrino beam where the baseline crosses the Earth's core. We study the detector requirements for a beta beam, a neutrino factory beam, and a superbeam, where we consider both the cases of small theta_13 and large theta_13, as suggested by the recent T2K and Double Chooz results. We illustrate that a flavor-clean beta beam best suits the requirements of such a detector, in particular, that PINGU may replace a magic baseline detector for small values of theta_13 -- even in the absence of any energy resolution capability. For large theta_13, however, a single-baseline beta beam experiment cannot compete if it is constrained by the CERN-SPS. For a neutrino factory, because of the missing charge identification possibility in the detector, a very good energy resolution is required. If this can be achieved, especially a low energy neutrino factory, which does not suffer from the tau contamination, may be an interesting option for large theta_13. For the superbeam, where we use the LBNE beam as a reference, electron neutrino flavor identification and statistics are two of the main limitations. Finally, we demonstrate that, at least in principle, neutrino factory and superbeam can measure the density of the Earth's core to the sub-percent level for sin^2 2theta_13 larger than 0.01.Comment: 34 pages, 15 figures. Minor changes and accepted in JHE

Non-Standard Interactions at a Neutrino Factory: Correlations and CP violation

We explore the potential of several Neutrino Factory (NF) setups to constrain, discover and measure new physics effects due to Non-Standard Interactions (NSI) in propagation through Earth matter. We first study the impact of NSI in the measurement of $\theta_{13}$: we find that these could be large due to strong correlations of $\theta_{13}$ with NSI parameters in the golden channel, and the inclusion of a detector at the magic baseline is crucial in order to reduce them as much as possible. We present, then, the sensitivity of the considered NF setups to the NSI parameters, paying special attention to correlations arising between them and the standard oscillation parameters, when all NSI parameters are introduced at once. Off-diagonal NSI parameters could be tested down to the level of $10^{-3}$, whereas the diagonal combinations $(\epsilon_{ee} - \epsilon_{\tau\tau})$ and $(\epsilon_{\mu\mu}-\epsilon_{\tau\tau})$ can be tested down to $10^{-1}$ and $10^{-2}$, respectively. The possibilities of observing CP violation in this context are also explored, by presenting a first scan of the CP discovery potential of the NF setups to the phases $\phi_{e\mu}, \phi_{e\tau}$ and $\delta$. We study separately the case where CP violation comes only from non-standard sources, and the case where it is entangled with the standard source, $\delta$. In case $\delta$ turns out to be CP conserving, the interesting possibility of observing CP violation for reasonably small values of the NSI parameters emerges.Comment: Final note added. 38 pages, 11 figure