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 $({\bar{\nu }}_{\mu }\to {\bar{\nu }}_{\mu }){\nu }_{\mu }\to {\nu }_{\mu }$ disappearance channel. For LBNE at $E_{\bar{\nu }}\simeq 1$ GeV the ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_{\mu }$ 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 ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ 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 ${\nu }_{\mu }\to {\nu }_{\mu }$, ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$, ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_{\mu }$ 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 ${\nu }_{\mu }\to {\nu }_e$, ${\nu }_{\mu }\to {\nu }_{\mu }$, and ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_{\mu }$ with energy (11.8-12) GeV, (8.9-12.3) GeV, (8.8-8.9) GeV. For LAGUNA a magic baseline appears for the ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_{\mu }$ channel only at (4.7-5.0) GeV in inverse hierarchy. We have also investigated a possible complementarity between T2K and No$\nu$a.

26 pages, 10 figures

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