Octant Degeneracy, Quadrant of leptonic CPV phase at Long Baseline Neutrino Experiments and Baryogenesis

In a recent work by us, we have studied, how CP violation discovery potential can be improved at long baseline neutrino experiments (LBNE/DUNE), by combining with its ND (near detector) and reactor experiments. In this work, we discuss how this study can be further analysed to resolve entanglement of the quadrant of leptonic CPV phase and Octant of atmospheric mixing angle $\theta_{23}$, at LBNEs. The study is done for both NH (Normal hierarchy) and IH (Inverted hierarchy), HO (Higher Octant) and LO (Lower Octant). We show how baryogenesis can enhance the effect of resolving this entanglement, and how possible values of the leptonic CP-violating phase $\delta_{CP}$ can be predicted in this context. With respect to the latest global fit data of neutrino mixing angles, we predict the values of $\delta_{CP}$ for different cases. In this context we present favoured values of $\delta_{CP}$ ($\delta_{CP}$ range at $\geq$ 2$\sigma$ ) constrained by the latest updated BAU range and also confront our predictions of $\delta_{CP}$ with an up-to-date global analysis of neutrino oscillation data. We find that some region of the favoured $\delta_{CP}$ parameter space lies within the best fit values around $\delta_{CP} \simeq 1.3\pi-1.4 \pi$. A detailed analytic and numerical study of baryogenesis through leptogenesis is performed in this framework in a model independent way.Comment: 14 pages, 5 figures, 2 Tables, New Analysi

Measuring the Sterile Neutrino CP Phase at DUNE and T2HK

The CP phases associated with the sterile neutrino cannot be measured in the dedicated short-baseline experiments being built to test the sterile neutrino hypothesis. On the other hand, these phases can be measured in long-baseline experiments, even though the main goal of these experiments is not to test or measure sterile neutrino parameters. In particular, the sterile neutrino phase $\delta_{24}$ affects the charged-current electron appearance data in long-baseline experiment. In this paper we show for the first time how well the sterile neutrino phase $\delta_{24}$ can be measured by the next-generation long-baseline experiments DUNE, T2HK (and T2HKK). We also show the expected precision with which this sterile phase can be measured by combining the DUNE data with data from T2HK or T2HKK. We also present the sensitivity of these experiments to the sterile mixing angles, both by themselves, as well as when DUNE is combined with T2HK or T2HKK.Comment: Published in EPJ C with minor correction

Exploring fake solutions in the sterile neutrino sector at long-baseline experiments

Active-sterile neutrino mixing is known to affect the neutrino oscillation probabilities at both short as well as long-baselines. In particular, constraints on active-sterile neutrino oscillation parameters can be obtained from long-baseline experiments such as T2HK and DUNE. We present here existence of fake solution in the appearance channel for the 3+1 scenario at long-baseline experiments. We show that the appearance probability is same for values of $\Delta m_{41}^2$ for which the fast oscillations are averaged out and for $\Delta m_{41}^2=(1/2)\Delta m_{31}^2$. The fake solution does not appear for the disappearance channel.Comment: 17 pages, 6 figures, accepted with some modification

Effect of Non Unitarity on Neutrino Mass Hierarchy determination at DUNE, NOν\nuA and T2K

The neutrino mass ordering is one of the principal unknowns in the neutrino sector. Long baseline neutrino experiments have the potential of resolving this issue as they are sensitive to large matter effects. The superbeam experiment DUNE is one of the most promising candidates to study the neutrino mass hierarchy, along with NO$\nu$A and T2K. But in the presence of non unitarity of the leptonic mixing matrix, the capability of such experiments to discriminate between the two hierarchies gets suppressed. The mass hierarchy sensitivity of DUNE decreases in the presence of new physics. In this paper we analyze the origin and extent of this loss of sensitivity at the level of oscillation probabilities, events, mass hierarchy sensitivity and the discovery reach of DUNE, NO$\nu$A and T2K.Comment: 23 pages, 9 figures, modified version, new text and figure added, accepted for publication in Nuclear Physics

Trilinear Neutral Gauge Boson Couplings

We study the CP even trilinear neutral gauge boson vertices at one-loop in the context of the Standard Model and the Minimal Supersymmetric Standard Model, assuming two of the vector bosons are on-shell. We also study the changes in the form-factors when these two bosons are off-shell.Comment: 19 pages, latex, a detailed study of off-shell form-factors included. To appear in International Journal of Modern Physics,

Synergy between DUNE and T2HKK to probe Invisible Neutrino Decay

We address the consequence of invisible neutrino decay in the context of two long base-line neutrino experiments; T2HKK (Tokai-to-Hyper-Kamiokande-to-Korea) and DUNE (Deep Underground Neutrino experiment). The main purpose of this work is to bring out the aspects of CC (charged current) and NC (neutral current) measurement at DUNE in the context of invisible neutrino decay. We find that the inclusion of NC measurements (NC) at DUNE with the charged current measurements (CC) enhances its ability to constrain invisible neutrino decay. This enhancement further increases if the total run-time changes from 7 years to 10 years at DUNE. The synergy between DUNE and T2HKK improves the constraints on invisible neutrino decay. The derived constraints are $\tau_{3}/m_{3}\leq5.51\times10^{-11}$ s/eV at $3\sigma$ CL. This constraint on the decay parameter increases further if we assume that all the oscillation parameters are measured precisely. In that case, the 3$\sigma$ constraint obtained by using the synergy between DUNE and T2HKK is $\tau_{3}/m_{3}\leq5.69\times10^{-11}$ s/eV. Again if nature prefers $\nu_{3}$ to be unstable and the decay width is $\tau_{3}/m_{3}= 2.2\times10^{-11}$ s/eV then this combination can exclude the no decay scenario at more than $5\sigma$ C. L. . Although the CP sensitivity is not much hindered in the presence of invisible neutrino decay, the measurements of $\theta_{23}$, as well as the octant sensitivity, are very much affected. Octant sensitivity improves in the lower octant in the presence of the invisible neutrino decay. However, the synergy between DUNE and T2HKK improves the overall octant sensitivity in the presence of invisible neutrino decay