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Register a new userUncertainties in the oscillation parameters measurement due to multi-nucleon effects at NO$ u$A Experiment
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Precise and adequate knowledge of neutrino scattering cross-sections and nuclear effects in them is very important to reduce the systematic uncertainties in neutrino beam oscillation experiments. The insufficiency in our present understanding of these effects inflicts the precision measurements of yet unknown neutrino oscillation parameters and some other experimentally observed anomalies in the neutrino sector. Another source of uncertainty is the energy dependence of neutrino oscillation probability which is a nontrivial function of the true incoming neutrino energy. This energy is reconstructed using different methods, which in turn is used in the analysis leading to the extraction of various neutrino oscillation parameters. The extraction of still unknown parameters like the leptonic CP violation phase demands the precision level in these measurements to be very high. In this work, we use the kinematic method of reconstruction of the incoming neutrino energy, both at the near and far detectors of NO$ u$A (USA) experiment, and investigate the role of multinucleon (MN) effects on the sensitivity measurement of various neutrino oscillation parameters. We use the values of various light neutrino oscillation parameters from their latest global fit values in our analysis.
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At present the three major unknowns in neutrino oscillation parameters are the mass hierarchy, the octant of $theta_{23}$ and the CP phase $delta_{CP}$. It is well known that the presence of hierarchy$-delta_{CP}$ and octant degeneracies affects the unambiguous determination of these parameters. In this paper we show that a comprehensive way to study the remaining parameter degeneracies is in the form of a generalized hierarchy-$theta_{23}$ - $delta_{CP}$ degeneracy. We show that the wrong-hierarchy and/or wrong-octant solutions can be further classified into eight different solutions depending on whether they occur with the wrong or right value of $delta_{CP}$. These eight solutions are different from the original eightfold degenerate solutions and can exist, in principle, even if $theta_{13}$ is known. These multiple solutions, apart from affecting the determination of the true hierarchy and octant, also affect the accurate estimation of $delta_{CP}$. We identify which of these eight different degenerate solutions can occur in the test ($theta_{23} - delta_{CP}$) parameter space, taking the long-baseline experiment NO$ u$A running in the neutrino mode as an example. The inclusion of the NO$ u$A antineutrino run removes the wrong-octant solutions appearing with both right and wrong hierarchy. Adding T2K data to this resolves the wrong hierarchy -- right octant solutions to a large extent. The remaining wrong hierarchy solutions can be removed by combining NO$ u$A + T2K with atmospheric neutrino data. We demonstrate this using ICAL@INO as the prototype atmospheric neutrino detector. We find that the degeneracies can be resolved at the $2sigma$ level by the combined data set, for the true parameter space considered in the study.
We present new $ u_murightarrow u_e$, $ u_murightarrow u_mu$, $overline{ u}_murightarrowoverline{ u}_e$, and $overline{ u}_murightarrowoverline{ u}_mu$ oscillation measurements by the NOvA experiment, with a 50% increase in neutrino-mode beam exposure over the previously reported results. The additional data, combined with previously published neutrino and antineutrino data, are all analyzed using improved techniques and simulations. A joint fit to the $ u_e$, $ u_mu$, $overline{ u}_e$, and $overline{ u}_mu$ candidate samples within the 3-flavor neutrino oscillation framework continues to yield a best-fit point in the normal mass ordering and the upper octant of the $theta_{23}$ mixing angle, with $Delta m^{2}_{32} = (2.41pm0.07)times 10^{-3}$ eV$^2$ and $sin^2theta_{23} = 0.57^{+0.03}_{-0.04}$. The data disfavor combinations of oscillation parameters that give rise to a large asymmetry in the rates of $ u_e$ and $overline{ u}_e$ appearance. This includes values of the CP-violating phase in the vicinity of $delta_text{CP} = pi/2$ which are excluded by $>3sigma$ for the inverted mass ordering, and values around $delta_text{CP} = 3pi/2$ in the normal ordering which are disfavored at 2$sigma$ confidence.
In neutrino oscillation experiments precise measurement of neutrino oscillation parameters is of prime importance as well as a challenge. To improve the statistics, presently running and proposed experiments are using heavy nuclear targets. These targets introduce nuclear effects and the quantification of these effects on neutrino oscillation parameters will be decisive in the prediction of neutrino oscillation physics. Limited understanding of neutrino nucleus interactions and inaccurate reconstruction of neutrino energy causes uncertainty in the cross section. The error in the determination of cross section which contributes to systematic error introduces error in the neutrino mixing parameters that are determined by these experiments. In this work we focus on the variation in the predictions of DUNE potential, arising due to systematic uncertainties, using two different event generators-GENIE and GiBUU. These generators have different and independent cross-section models. To check the DUNE potential with the two generators as mentioned we have checked the senstivity studies of DUNE for CP violation, mass hierarchy and octant degeneracy.
Recent neutrino oscillation experiments used high atomic number nuclear targets to attain sufficient interaction rates. The use of these complex targets introduced systematic uncertainties due to the nuclear effects in the experimental observable and need to be measured properly to pin down the discovery. Through this simulation work, we are trying to quantify the nuclear effects in the Ar target with the H target which are proposed to be used at DUNE far detector and near detector respectively. The DUNE flux is peaking around 2.5 GeV and CCRES is the dominant process at this energy. So, this work will be focused only on the CCQE and CCRES interactions and the simulations will be done using two different neutrino event generators. To quantify the systematic uncertainties in the observables, we presented the ratio of the oscillation probability (P(Ar)/P(H)) as a function of reconstructed neutrino energy for CCRES channels.
The main goal of the IceCube Deep Core Array is to search for neutrinos of astrophysical origins. Atmospheric neutrinos are commonly considered as a background for these searches. We show that the very high statistics atmospheric neutrino data can be used to obtain precise measurements of the main oscillation parameters.
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