The mass hierarchy with atmospheric neutrinos at INO

We study the neutrino mass hierarchy at the magnetized Iron CALorimeter (ICAL) detector at India-based Neutrino Observatory with atmospheric neutrino events generated by the Monte Carlo event generator Nuance. We judicially choose the observables so that the possible systematic uncertainties can be reduced. The resolution as a function of both energy and zenith angle simultaneously is obtained for neutrinos and anti-neutrinos separately from thousand years un-oscillated atmospheric neutrino events at ICAL to migrate number of events from neutrino energy and zenith angle bins to muon energy and zenith angle bins. The resonance ranges in terms of directly measurable quantities like muon energy and zenith angle are found using this resolution function at different input values of $\theta_{13}$. Then, the marginalized $\chi^2$s are studied for different input values of $\theta_{13}$ with its resonance ranges taking input data in muon energy and zenith angle bins. Finally, we find that the mass hierarchy can be explored up to a lower value of $\theta_{13}\approx 5^\circ$ with confidence level $>$ 95% in this set up.Comment: some clarifications added, version accepted in PLB, 12 pages, 34 figure

Prospects of measuring the leptonic CP phase with atmospheric neutrinos

We have studied the prospects of measuring the CP violating phase with atmospheric neutrinos at a large magnetized iron calorimeter detector considering the muons (directly measurable) of the neutrino events generated by a MonteCarlo event generator Nuance. The effect of $\theta_{13}$ and $\delta_{CP}$ appears dominantly neither in atmospheric neutrino oscillation nor in solar neutrino oscillation, but appears as subleading in both cases. These are observable in range of $E \sim 1$ GeV for atmospheric neutrino, where solar and atmospheric oscillation couple. In this regime, the quasi-elastic events dominate and the energy resolution is very good, but the angular resolution is very poor. Unlike beam experiments this poor angular resolution acts against its measurements. However, we find that one can be able to distinguish $\delta_{CP}\approx 0^\circ$ and $180^\circ$ at 90% confidence level. We find no significant sensitivity for $\delta_{CP}\approx 90^\circ$ or $270^\circ$.Comment: 9 pages, 7 figures, clarifying discussions on results added; accepted in Phys. Rev.

The quark-lepton unification : LHC data and neutrino masses

The recent discovery of nonzero $\theta_{13}$ (equal to Cabbibo angle $\theta_C$ up to a factor of $\sqrt{2}$), the masses of supersymmetric particles \gapp TeV from LHC data, and the sum of three active neutrino masses \sum_i m_{\nu_i}\lapp 1 eV from the study of large scale structure of the universe motivate to study whether quark and lepton mixing have the same origin at the grand unification scale. We find that both results from neutrino experiments and LHC are complementary in quark-lepton unified model. A new constraint on SUSY parameters appears from electroweak symmetry breaking with a new correlation between the lower bounds on sparticle masses and the upper bound on $\sum_i m_{\nu_i}$. In addition, we find that only $\mu>0$ (which is favored by $(g-2)$ of muon) is allowed and m_{\tilde q, \tilde \l} \gapp TeV if \sum_i m_{\nu_i} \lapp 1 eV. On the other hand, a small change in lower limit on $\theta_{13}$ from zero leads to a large increase in lower limits on sparticles masses (\gapp 2 TeV), which are also the bounds if recently discovered boson at LHC with mass around 125 GeV is the Higgs boson.Comment: 5 pages, 2 figures, impact of Higgs boson at mass 125 GeV added, final version, accepted in Phys. Lett.

Exploration prospects of a long baseline Beta Beam neutrino experiment with an iron calorimeter detector

A high intensity source of a single neutrino flavour with known spectrum is most desirable for precision measurements, the consensus direction for the future. The beta beam is an especially suitable option for this. We discuss the prospects of a very long baseline beta beam experiment with a magnetized iron calorimeter detector. In particular, with the source at CERN and the detector at the proposed India-based Neutrino Observatory (INO) the baseline is near the `magic' value where the effect of the CP phase is small. We observe that this experiment will be well suited to determine the sign of $m_3^2 - m_2^2$ and will be capable of probing $\theta_{13}$ down to about 1$^\circ$.Comment: 11 pages, 6 figures, Latex, more discussions added, version accepted in Phys. Lett.