Muonless Events in ICAL at INO

The primary physics signal events in the ICAL at INO are the ${\nu}_{\mu}$ charged current (CC) interactions with a well defined muon track. Apart from these events, ICAL can also detect other types of neutrino interactions, i.e. the electron neutrino charged current interactions and the neutral current events. It is possible to have a dataset containing mostly ${\nu}_e$CC events, by imposing appropriate selection cuts on the events. The ${\nu}_{\mu}$ CC and the neutral current events form the background to these events. This study uses the Monte Carlo generated neutrino events, to design the necessary selection cuts to obtain a ${\nu}_e$ CC rich dataset. An optimized set of constraints are developed which balance the need for improving the purity of the sample and having a large enough event sample. Depending on the constraints used, one can obtain a neutrino data sample, with the purity of ${\nu}_e$ events varying between 55% to 70%.Comment: 21 pages, 6 figure

Testing LSND at long-baseline neutrino experiments

Recently it was suggested that two very different mass-squared differences play a role in atmospheric neutrino oscillations. The larger of these also accounts for the LSND result and the smaller of these also drives the solar neutrino oscillations. We consider the predictions of this scheme for long-baseline experiments. We find that high statistics experiments, such as MINOS, can observe a clean signal for this scheme, which is clearly distinguishable from the usual scheme of atmospheric neutrino oscillations driven by a single mass-squared difference.Comment: 13 pages, 3 figure

Non-Zero θ13\theta_{13} and δCP\delta_{CP} in a Neutrino Mass Model with A4A_4 Symmetry

In this paper, we consider a neutrino mass model based on $A_4$ symmetry. The spontaneous symmetry breaking in this model is chosen to obtain tribimaximal mixing in the neutrino sector. We introduce $Z_2 \times Z_2$ invariant perturbations in this model which can give rise to acceptable values of $\theta_{13}$ and $\delta_{CP}$. Perturbation in the charged lepton sector alone can lead to viable values of $\theta_{13}$, but cannot generate $\delta_{CP}$. Perturbation in the neutrino sector alone can lead to acceptable $\theta_{13}$ and maximal CP violation. By adjusting the magnitudes of perturbations in both sectors, it is possible to obtain any value of $\delta_{CP}$.Comment: 16 pages, 3 figure

The need for an early anti-neutrino run of NOvA

The moderately large value of \ty, measured recently by reactor experiments, is very welcome news for the future neutrino experiments. In particular, the \nova experiment, with 3 years each of $\nu$ and \anu runs, will be able to determine the mass hierarchy if one of the following two favourable combinations is true: normal hierarchy with -180^\circ \leq \dcp \leq 0 or inverted hierarchy with 0\leq \dcp \leq 180^\circ. In this report, we study the hierarchy reach of the first 3 years of \nova data. Since \sin^2 2 \tz is measured to be non-maximal, \tz can be either in the lower or higher octant. Pure $\nu$ data is affected by \ty-hierarchy and octant-hierarchy degeneracies, which limit the hierarchy sensitivity of such data. A combination of $\nu$ and \anu data is not subject to these degeneracies and hence has much better hierarchy discrimination capability. We find that, with a 3 year $\nu$ run, hierarchy determination is possible for only two of the four octant-hierarchy combinations. Equal 1.5 year runs in $\nu$ and \anu modes give good hierarchy sensitivity for all the four combinations

Re-examining sin(2beta) and Delta m(d) from evolution of B(d) mesons with decoherence

In the time evolution of neutral meson systems, a perfect quantum coherence is usually assumed. The important quantities of the B(d) system, such as sin (2beta) and Delta m(d), are determined under this assumption. However, the meson system interacts with its environment. This interaction can lead to decoherence in the mesons even before they decay. In our formalism this decoherence is modelled by a single parameter lambda. It is desirable to re-examine the procedures of determination of sin(2beta) and Delta m(d) in meson systems with decoherence. We find that the present values of these two quantities are modulated by lambda. Re-analysis of B(d) data from B-factories and LHCb can lead to a clean determination of lambda, sin(2beta) and Delta m(d).Comment: Version accepted for publication in Physics Letters

Getting the best out of T2K and NOvA

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.Comment: Version published in Phys. Rev.