Description
Recent results of the MINOS experiment indicate that
$\theta_{23}$ is not maximal. Global fits to neutrino
data give two nearly degenerate solutions for $\theta_{23}$,
one in the lower octant (LO: $\theta_{23}<\pi/4$)
and the other in the higher octant (HO: $\theta_{23}>\pi/4$).
$\nu_{\mu}\rightarrow\nu_{e}$ oscillations are
sensitive to the octant and are capable of resolving
this degeneracy. We consider the ability of current
and near future long baseline experiments to resolve the
octant. As in the case of hierarchy, there exist favorable
(unfavorable) values of $\delta_{CP}$ for which octant
resolution is easy (challenging). Unlike in the case of hierarchy,
the unfavorable $\delta_{CP}$ values of the neutrino data
are favorable for the anti-neutrino data and vice-verse.
We compute the combined sensitivity of T2K and NO$\nu$A
to resolve the octant. Because of the hierarchy-$\delta_{CP}$
degeneracy, the impact of hierarchy on octant resolution has to be
taken into account. If LO is the true octant, then NO$\nu$A
can rule out HO at $2\sigma$ C.L., irrespective of the hierarchy.
Addition of T2K data improves the octant sensitivity. If the
combination HO and normal hierarchy is true, then the combined
data from NO$\nu$A and T2K with its designed run of 5 years
in neutrino mode, is incapable of a $2\sigma$ resolution of
octant. This becomes possible for all four combinations of
octant and hierarchy if T2K has balanced neutrino and
anti-neutrino runs of 2.5 years each.
Primary author
Mr
Suprabh Prakash
(Indian Institute of Technology - Bombay)
Co-authors
Prof.
Sanjib Kumar Agarwalla
(Institute of Physics, Bhubaneshwar)
Prof.
Uma Sankar Sankhagiri
(Indian Institute of Technology Bombay)
