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Agarwalla, S. K., Prakash, S., Raut, S. K., & Sankar, S. U. (2012). Potential of optimized NOvA for large theta(13) and combined performance with a LArTPC & T2K. J. High Energy Phys., 12(12), 075–21pp.
Abstract: NO nu A experiment has reoptimized its event selection criteria in light of the recently measured moderately large value of theta(13). 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 delta(CP), NO nu A sensitivity to mass hierarchy and leptonic CP violation is increased by 20%. Addition of 5 years of neutrino data from T2K to NO nu A more than doubles the range of delta(CP) for which the leptonic CP violation can be discovered,compared to stand alone NO nu A. But for unfavourable values of delta(CP), the combination of NO nu A 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 NO nu A site. The capabilities of such a detector are equivalent to those of NO nu A in all respects. We find that combined data from 10 kt liquid argon detector (3 years of nu + 3 years of (nu) over bar run), NO nu A (6 years of nu + 6 years of nu run) and T2K (5 years of nu run) can give a close to 2 sigma hint of hierarchy discovery for all values of delta(CP). With this combined data,we can achieve CP violation discovery at 95% C.L. for roughly 60% values of delta(CP).
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Khatun, A., Chatterjee, S. S., Thakore, T., & Agarwalla, S. K. (2020). Enhancing sensitivity to non-standard neutrino interactions at INO combining muon and hadron information. Eur. Phys. J. C, 80(6), 533–17pp.
Abstract: In this paper, we explore the impact of flavor violating neutral current non-standard interaction (NSI) parameter epsilon(mu tau) in the oscillation of atmospheric neutrinos and antineutrinos separately using the 50 kt magnetized ICAL detector at INO. We find that due to non-zero epsilon(mu tau), nu(mu) -> nu(mu) and (nu) over bar (mu) -> (nu) over bar (mu) transition probabilities get modified substantially at higher energies and longer baselines, where vacuum oscillation dominates. We demonstrate for the first time that by adding the hadron energy information along with the muon energy and muon direction in each event, the sensitivity of ICAL to the NSI parameter epsilon(mu tau) can be enhanced significantly. The most optimistic bound on epsilon(mu tau) that we obtain is – 0.01 < epsilon(mu tau) < 0.01 at 90% C.L. using 500 kt.yr exposure and considering E-mu, cos theta(mu), and E-had' as observables in their ranges of [1, 21] GeV, [- 1, 1], and [0, 25] GeV, respectively. We discuss for the first time the importance of the charge identification capability of the ICAL detector to have better constraints on epsilon(mu t). We also study the impact of non-zero epsilon(mu tau) on mass hierarchy determination and precision measurement of oscillation parameters.
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Agarwalla, S. K., Bagchi, P., Forero, D. V., & Tortola, M. (2015). Probing non-standard interactions at Daya Bay. J. High Energy Phys., 07(7), 060–33pp.
Abstract: In this article we consider the presence of neutrino non-standard interactions (NSI) in the production and detection processes of reactor antineutrinos at the Daya Bay experiment. We report for the first time, the new constraints on the flavor non-universal and flavor universal charged-current NSI parameters, estimated using the currently released 621 days of Daya Bay data. New limits are placed assuming that the new physics effects are just inverse of each other in the production and detection processes. With this special choice of the NSI parameters, we observe a shift in the oscillation amplitude without distorting the L/E pattern of the oscillation probability. This shift in the depth of the oscillation dip can be caused by the NSI parameters as well as by theta(13), making it quite difficult to disentangle the NSI effects from the standard oscillations. We explore the correlations between the NSI parameters and theta(13) that may lead to significant deviations in the reported value of the reactor mixing angle with the help of iso-probability surface plots. Finally, we present the limits on electron, muon/tau, and flavor universal (FU) NSI couplings with and without considering the uncertainty in the normalization of the total event rates. Assuming a perfect knowledge of the event rates normalization, we find strong upper bounds similar to 0.1% for the electron and FU cases improving the present limits by one order of magnitude. However, for a conservative error of 5% in the total normalization, these constraints are relaxed by almost one order of magnitude.
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Agarwalla, S. K., Blennow, M., Fernandez-Martinez, E., & Mena, O. (2011). Neutrino probes of the nature of light dark matter. J. Cosmol. Astropart. Phys., 09(9), 004–19pp.
Abstract: Dark matter particles gravitationally trapped inside the Sun may annihilate into Standard Model particles, producing a flux of neutrinos. The prospects of detecting these neutrinos in future multi-kt neutrino detectors designed for other physics searches are explored here. We study the capabilities of a 34/100 kt liquid argon detector and a 100 kt magnetized iron calorimeter detector. These detectors are expected to determine the energy and the direction of the incoming neutrino with unprecedented precision allowing for tests of the dark matter nature at very low dark matter masses, in the range of 10-25 GeV. By suppressing the atmospheric background with angular cuts, these techniques would be sensitive to dark matter-nucleon spin-dependent cross sections at the fb level, reaching down to a few ab for the most favorable annihilation channels and detector technology.
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