Evidence for leptonic CP phase from NOνA, T2K and ICAL

Ghosh, Monojit ; Ghoshal, Pomita ; Goswami, Srubabati ; Raut, Sushant K. (2016) Evidence for leptonic CP phase from NOνA, T2K and ICAL Pramana, 86 (2). pp. 387-393. ISSN 0304-4289


Official URL: http://www.ias.ac.in/describe/article/pram/086/02/...

Related URL: http://dx.doi.org/10.1007/s12043-015-1159-5


The phenomenon of neutrino oscillation is now well understood from the solar, atmospheric, reactor and accelerator neutrino experiments. This oscillation is characterized by a unitary PMNS matrix which is parametrized by three mixing angles (θ12, θ23 and θ13) and one phase (δCP) known as the leptonic CP phase. Neutrino oscillation also involves two mass squared differences: the solar mass square difference (Δ21 = m22 − m21 and the atmospheric mass square difference (Δ31 = |m23 − m21|). Though there is already significant amount of information about the three mixing angles, the CP phase is still unknown. Apart from the CP phase, one should also know what is the true nature of the neutrino mass hierarchy, i.e., normal (m3 > m1: NH) or inverted (m1 > m3: IH) and what is the true octant of θ23, i.e., lower (θ23 < 45∘: LO) or higher (θ23 > 45: HO). The long-baseline experiments (LBL) have CP sensitivity coming from the appearance channel (νμ → νe). On the other hand, atmospheric neutrinos are known to have negligible CP sensitivity. In this work, we study the synergy between the LBL experiment NOνA, T2K and the atmospheric neutrino experiment ICAL@INO for obtaining the first hint of CP violation in the lepton sector. We find that due to the lack of knowledge of hierarchy and octant, CP sensitivity of NOνA/T2K is poorer for some parameter ranges. Addition of ICAL data to T2K and NOνA can exclude these spurious wrong-hierarchy and /or wrong-octant solutions and cause a significant increase in the range of δCP values for which a hint of CP violation can be achieved. Similarly, the precision with which δCP can be measured also improves with the inclusion of ICAL data.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Neutrino Oscillation; Leptonic CP Phase; Long-baseline Neutrino Experiments; Atmospheric Neutrino Experiments
ID Code:108721
Deposited On:01 Feb 2018 04:37
Last Modified:01 Feb 2018 04:37

Repository Staff Only: item control page