Study of parameter degeneracy and hierarchy sensitivity of NO$\nu$A in presence of sterile neutrino

Understand

The first hint of the neutrino mass hierarchy is believed to come from the long-baseline experiment NO$\nu$A.

• Recent results from the NO$\nu$A shows a mild preference towards the CP phase $\delta_{13} = -90^\circ$ and normal hierarchy.
• Fortunately this is the favorable area of the parameter space which does not suffer from the hierarchy-$\delta_{13}$ degeneracy and thus NO$\nu$A can have good hierarchy sensitivity for this true combination of hierarchy and $\delta_{13}$.
• Apart from the hierarchy-$\delta_{13}$ degeneracy there is also the octant-$\delta_{13}$ degeneracy.