Long baseline neutrino experiments, mass hierarchy and delta(CP)

Abstract

We investigate the possibilities offered by the long baseline experiments T2K, No$\nu$a, LBNE and LAGUNA for the evaluation of the neutrino mass hierarchy and CP violating phase $\delta_{CP}$. We consider a neutrino and antineutrino energy in the interval [0.5,12] GeV. It is found that the clearest possible distinction between the two hierarchy signatures is provided by LAGUNA for an (anti)neutrino energy $E_{(\bar\nu)\nu}\simeq 0.5$ GeV in the $(\bar\nu_{\mu} \rightarrow \bar\nu_{\mu}) \nu_{\mu}\rightarrow \nu_{\mu}$ disappearance channel. For LBNE at $E_{\bar\nu}\simeq 1$ GeV the $\bar\nu_{\mu}\rightarrow \bar\nu_{\mu}$ channel may also provide a distinction, although not so clear, and for No$\nu$a this may be even less clear. These results are essentially the same for the $\theta_{23}$ first and second octant solutions. As for $\delta_{CP}$ determination, LAGUNA also offers the best chances at $E_{\bar\nu}\simeq 0.5$ GeV in the $\bar\nu_{\mu}\rightarrow \bar\nu_{e}$ channel with $\theta_{23}$ in either octant. Regarding nonstandard interactions, the best possibility for their investigation resides in No$\nu$a whose source-far detector distance can become a magic baseline if the hierarchy is normal for channels $\nu_{\mu}\rightarrow \nu_{\mu}$, $\bar\nu_{\mu}\rightarrow \bar\nu_{e}$, $\bar\nu_{\mu}\rightarrow \bar\nu_{\mu}$ with energy (8.9-9.1) GeV, (11.6-12) GeV, (8.8-12) GeV. If the hierarchy is inverse, magic baselines for No$\nu$a occur for $\nu_{\mu}\rightarrow \nu_{e}$, $\nu_{\mu}\rightarrow \nu_{\mu}$, and $\bar\nu_{\mu}\rightarrow \bar\nu_{\mu}$ with energy (11.8-12) GeV, (8.9-12.3) GeV, (8.8-8.9) GeV. For LAGUNA a magic baseline appears for the $\bar\nu_{\mu}\rightarrow \bar\nu_{\mu}$ channel only at (4.7-5.0) GeV in inverse hierarchy. We have also investigated a possible complementarity between T2K and No$\nu$a.