Sushant K. Raut

Potential of optimized NOνA for large θ13 & combined performance with a LArTPC & T2K

A bstractNOνA experiment has reoptimized its event selection criteria in light of the recently measured moderately large value of θ13. We study the improvement in the sensitivity to the neutrino mass hierarchy and to leptonic CP violation due to these new features. For favourable values of δCP, NOνA sensitivity to mass hierarchy and leptonic CP violation is increased by 20%. Addition of 5 years of neutrino data from T2K to NOνA more than doubles the range of δCP for which the leptonic CP violation can be discovered, compared to stand alone NOνA. But for unfavourable values of δCP, the combination of NOνA and T2K are not enough to provide even a 90% C.L. hint of hierarchy discovery. Therefore, we further explore the improvement in the hierarchy and CP violation sensitivities due to the addition of a 10 kt liquid argon detector placed close to NOνA site. The capabilities of such a detector are equivalent to those of NOνA in all respects. We find that combined data from 10 kt liquid argon detector (3 years of ν + 3 years of

Neutrino Mass Hierarchy and Octant Determination with Atmospheric Neutrinos

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Getting the Best Out of T2K and NOvA

run), NOνA (6 years of ν + 6 years of

A combined study of source, detector and matter non-standard neutrino interactions at DUNE

\overline{\nu}

Can atmospheric neutrino experiments provide the first hint of leptonic CP violation

run) and T2K (5 years of ν run) can give a close to 2σ hint of hierarchy discovery for all values of δCP. With this combined data, we can achieve CP violation discovery at 95% C.L. for roughly 60% values of δCP.

EFFECT OF NONZERO θ13 ON THE MEASUREMENT OF θ23

The recent discovery by the Daya-Bay and RENO experiments, that θ(13) is nonzero and relatively large, significantly impacts existing experiments and the planning of future facilities. In many scenarios, the nonzero value of θ(13) implies that θ(23) is likely to be different from π/4. Additionally, large detectors will be sensitive to matter effects on the oscillations of atmospheric neutrinos, making it possible to determine the neutrino mass hierarchy and the octant of θ(23). We show that a 50 kT magnetized liquid argon neutrino detector can ascertain the mass hierarchy with a significance larger than 4σ with moderate exposure times, and the octant at the level of 2-3σ with greater exposure.

New look at the degeneracies in the neutrino oscillation parameters, and their resolution by T2K, NO nu A and ICAL

We explore the combined physics potential of T2K and NOvA in light of the moderately large measured value of theta13. For sin^2 2*theta13 = 0.1, which is close to the best fit value, a 90% C.L. evidence for the hierarchy can be obtained only for the combinations (Normal hierarchy, -170 <= deltaCP <= 0) and (Inverted hierarchy, 0 <= deltaCP <= 170), with the currently planned runs of NOvA and T2K. However, the hierarchy can essentially be determined for any value of deltaCP, if the statistics of NOvA are increased by 50% and those of T2K are doubled. Such an increase will also give an allowed region of deltaCP around its true value, except for the CP conserving cases deltaCP = 0 or 180. We demonstrate that any measurement of deltaCP is not possible without first determining hierarchy. We find that comparable data from a shorter baseline (L ~ 130 km) experiment will not lead to any significant improvement.

Magical properties of a 2540 km baseline superbeam experiment

A bstractWe simultaneously investigate source, detector and matter non-standard neutrino interactions at the proposed DUNE experiment. Our analysis is performed using a Markov Chain Monte Carlo exploring the full parameter space. We find that the sensitivity of DUNE to the standard oscillation parameters is worsened due to the presence of non-standard neutrino interactions. In particular, there are degenerate solutions in the leptonic mixing angle θ23 and the Dirac CP-violating phase δ. We also compute the expected sensitivities at DUNE to the non-standard interaction parameters. We find that the sensitivities to the matter non-standard interaction parameters are substantially stronger than the current bounds (up to a factor of about 15). Furthermore, we discuss correlations between the source/detector and matter non-standard interaction parameters and find a degenerate solution in θ23. Finally, we explore the effect of statistics on our results.

Exploring Source and Detector Non-Standard Neutrino Interactions at ESS

The measurement of a non-zero value of the 1-3 mixing angle has paved the way for the determination of leptonic CP violation. However the current generation long-baseline experiments T2K and NOvA have limited sensitivity to delta_{CP}. In this paper we show for the first time, the significance of that atmospheric neutrino experiments in providing the first hint of CP violation in conjunction with T2K and NOvA. In particular, we find that adding atmospheric neutrino data from the ICAL detector at the India-based Neutrino Observatory (INO) to T2K and NOvA results in a two-fold increase in the range of delta_{CP} values for which a 2 sigma hint of CP violation can be obtained. In fact in the parameter region unfavorable for the latter experiments, the first signature of CP violation may well come from the inclusion of atmospheric neutrino data.

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The moderately large measured value of theta13 signals a departure from the approximate two-flavour oscillation framework. As a consequence, the relation between the value of theta23 in nature, and the mixing angle measured in muon neutrino disappearance experiments is non-trivial. In this paper, we calculate this relation analytically. We also derive the correct conversion between degenerate values of theta23 in the two octants. Through simulations of a muon neutrino disappearance experiment, we show that there are observable consequences of not using the correct relation in calculating oscillation probabilities. These include a wrong best-fit value for theta23, and spurious sensitivity to the octant of theta23.