arXiv subjects

Sanjib Kumar Agarwalla

Publications and source records attributed to Sanjib Kumar Agarwalla.

At least 37 records · Page 2Linked to original sources

arXiv2023

Probing dark matter inside Earth using atmospheric neutrino oscillations at INO-ICAL

The interior of Earth's core can be explored using weak interactions of atmospheric neutrinos. This would complement gravitational and seismic measurements, paving the way for multimessenger tomography of Earth. Oscillations of atmospheric neutrinos passing through Earth are affected by the ambient electron density. We demonstrate that atmospheric neutrinos can probe the possible existence of dark matter inside Earth's core in a unique way - by measuring the amount of baryonic matter using neutrino oscillations. We find that a detector like ICAL at INO with muon charge identification capability can be sensitive to dark matter with $\sim5\%-6\%$ mass of Earth, at 1$σ$ level with 500 kt$\cdot$yr exposure. We show that while it will not be possible to identify the dark matter profile using neutrino oscillation experiments, the baryonic matter profile inside the core can be probed with atmospheric neutrinos.

hep-ph↗

arXiv2023

Flavor-dependent long-range neutrino interactions in DUNE & T2HK: alone they constrain, together they discover

Discovering new neutrino interactions would represent evidence of physics beyond the Standard Model. We focus on new flavor-dependent long-range neutrino interactions mediated by ultra-light mediators, with masses below $10^{-10}$ eV, introduced by new lepton-number gauge symmetries $L_e-L_μ$, $L_e-L_τ$, and $L_μ-L_τ$. Because the interaction range is ultra-long, nearby and distant matter - primarily electrons and neutrons - in the Earth, Moon, Sun, Milky Way, and the local Universe, may source a large matter potential that modifies neutrino oscillation probabilities. The upcoming Deep Underground Neutrino Experiment (DUNE) and the Tokai-to-Hyper-Kamiokande (T2HK) long-baseline neutrino experiments will provide an opportunity to search for these interactions, thanks to their high event rates and well-characterized neutrino beams. We forecast their probing power. Our results reveal novel perspectives. Alone, DUNE and T2HK may strongly constrain long-range interactions, setting new limits on their coupling strength for mediators lighter than $10^{-18}$ eV. However, if the new interactions are subdominant, then both DUNE and T2HK, together, will be needed to discover them, since their combination lifts parameter degeneracies that weaken their individual sensitivity. DUNE and T2HK, especially when combined, provide a valuable opportunity to explore physics beyond the Standard Model.

hep-ph↗

arXiv2023

Locating the Core-Mantle Boundary using Oscillations of Atmospheric Neutrinos

Atmospheric neutrinos provide a unique avenue to explore the internal structure of Earth based on weak interactions, which is complementary to seismic studies and gravitational measurements. In this work, we demonstrate that the atmospheric neutrino oscillations in the presence of Earth matter can serve as an important tool to locate the core-mantle boundary (CMB). An atmospheric neutrino detector like the proposed 50 kt magnetized ICAL at INO can observe the core-passing neutrinos efficiently. These neutrinos would have experienced the MSW resonance and the parametric or neutrino oscillation length resonance. The net effect of these resonances on neutrino flavor conversions depends upon the location of CMB and the density jump at that radius. We quantify the capability of ICAL to measure the location of CMB in the context of multiple three-layered models of Earth. For the model where the density and the radius of core are kept flexible while the mass and radius of Earth as well as the densities of outer and inner mantle are fixed, ICAL can determine the location of CMB with a 1$σ$ precision of about 250 km with an exposure of 1000 kt$\cdot$yr. With the 81-layered PREM profile, this $1σ$ precision would be about 350 km. The charge identification capability of ICAL plays an important role in achieving this precision.

hep-ph↗

arXiv2023

Enhancing Sensitivity to Leptonic CP Violation using Complementarity among DUNE, T2HK, and T2HKK

After the landmark discovery of non-zero $θ_{13}$ by the modern reactor experiments, unprecedented precision on neutrino mass-mixing parameters has been achieved over the past decade. This has set the stage for the discovery of leptonic CP violation (LCPV) at high confidence level in the next-generation long-baseline neutrino oscillation experiments. In this work, we explore in detail the possible complementarity among the on-axis DUNE and off-axis T2HK experiments to enhance the sensitivity to LCPV suppressing the $θ_{23}-δ_{\mathrm{CP}}$ degeneracy. We find that none of these experiments individually can achieve the milestone of 3$σ$ LCPV for at least 75% choices of $δ_{\mathrm{CP}}$ in its entire range of $[-180^{\circ} , 180^{\circ}]$, with their nominal exposures and systematic uncertainties. However, their combination can attain the same for all values of $θ_{23}$ with only half of their nominal exposures. We observe that the proposed T2HKK setup in combination with DUNE can further increase the CP coverage to more than 80% with only half of their nominal exposures. We study in detail how the coverage in $δ_{\mathrm{CP}}$ for $\ge$ 3$σ$ LCPV depends on the choice of $θ_{23}$, exposure, optimal runtime in neutrino and antineutrino modes, and systematic uncertainties in these experiments in isolation and combination. We find that with an improved systematic uncertainty of 2.7% in appearance mode, the standalone T2HK setup can provide a CP coverage of around 75% for all values of $θ_{23}$. We also discuss the pivotal role of intrinsic, extrinsic, and total CP asymmetries in the appearance channel and extrinsic CP asymmetries in the disappearance channel while analyzing our results.

hep-ph↗

arXiv2023

Constraining Lorentz Invariance Violation with Next-Generation Long-Baseline Experiments

Unified theories such as string theory and loop quantum gravity allow the Lorentz Invariance Violation (LIV) at the Planck Scale ($M_P \sim 10^{19}$ GeV). Using an effective field theory, this effect can be observed at low energies in terms of new interactions with a strength of $\sim 1/M_P$. These new interactions contain operators with LIV coefficients which can be CPT-violating or CPT-conserving. In this work, we study in detail how these LIV parameters modify the transition probabilities in the next-generation long-baseline experiments, DUNE and T2HK. We evaluate the sensitivities of these experiments in isolation and combination to constrain the off-diagonal CPT-violating ($a_{eμ}$, $a_{eτ}$, $a_{μτ}$) and CPT-conserving ($c_{eμ}$, $c_{eτ}$, $c_{μτ}$) LIV parameters. We derive approximate compact analytical expressions of $ν_μ\toν_e$ and $ν_μ\toν_μ$ probabilities in the presence of these LIV parameters to explain our numerical results. We explore the possible correlations and degeneracies between these LIV parameters & 3$ν$ parameters $θ_{23}$ & $δ_{\rm CP}$. We find that for non-maximal values of $θ_{23}$, there exist degenerate solutions in its opposite octant for standalone DUNE and T2HK. These degeneracies disappear when we combine the data from DUNE and T2HK. In case of no-show, we place the expected bounds on these CPT-violating and CPT-conserving LIV parameters at 95% C.L. using the standalone DUNE, T2HK, and their combination. We observe that due to its access to a longer baseline and high-energy neutrinos, DUNE has a better reach in probing all these LIV parameters as compared to T2HK. Since the terms containing the CPT-conserving LIV parameters are proportional to neutrino energy in oscillation probabilities, T2HK is almost insensitive to the CPT-conserving LIV parameters because it mostly deals with sub-GeV neutrinos.

hep-ph↗

arXiv2023

Discriminating between Lorentz violation and non-standard interactions using core-passing atmospheric neutrinos at INO-ICAL

Precision measurements of neutrino oscillation parameters have provided a tremendous boost to the search for sub-leading effects due to several beyond the Standard Model scenarios in neutrino oscillation experiments. Among these, two of the well-studied scenarios are Lorentz violation (LV) and non-standard interactions (NSI), both of which can affect neutrino oscillations significantly. We point out that, at a long-baseline experiment where the neutrino oscillation probabilities can be well-approximated by using the line-averaged constant matter density, the effects of these two scenarios can mimic each other. This would allow the limits obtained at such an experiment on one of the above scenarios to be directly translated to the limits on the other scenario. However, for the same reason, it would be difficult to distinguish between LV and NSI at a long-baseline experiment. We show that the observations of atmospheric neutrinos, which travel a wide range of baselines and may encounter sharp density changes at the core-mantle boundary, can break this degeneracy. We observe that identifying neutrinos and antineutrinos separately, as can be done at INO-ICAL, can enhance the capability of atmospheric neutrino experiments to discriminate between these two new-physics scenarios.

hep-ph↗

arXiv2022

Model-Independent Constraints on Non-Unitary Neutrino Mixing from High-Precision Long-Baseline Experiments

Our knowledge on the active 3$ν$ mixing angles ($θ_{12}$, $θ_{13}$, and $θ_{23}$) and the CP phase $δ_{\mathrm{CP}}$ is becoming accurate day-by-day enabling us to test the unitarity of the leptonic mixing matrix with utmost precision. Future high-precision long-baseline experiments are going to play an important role in this direction. In this work, we study the impact of possible non-unitary neutrino mixing (NUNM) in the context of next-generation long-baseline experiments DUNE and T2HKK/JD+KD having one detector in Japan (T2HK/JD) and a second detector in Korea (KD). We estimate the sensitivities of these setups to place direct, model-independent, and competitive constraints on various NUNM parameters. We demonstrate the possible correlations between the NUNM parameters, $θ_{23}$, and $δ_{\mathrm{CP}}$. Our numerical results obtained using only far detector data and supported by simple approximate analytical expressions of the oscillation probabilities in matter, reveal that JD+KD has better sensitivities for $|α_{21}|$ and $α_{22}$ as compared to DUNE, due to its larger statistics in the appearance channel and less systematic uncertainties in the disappearance channel, respectively. For $|α_{31}|$, $|α_{32}|$, and $α_{33}$, DUNE gives better constraints as compared to JD+KD, due to its larger matter effect and wider neutrino energy spectrum. For $α_{11}$, both DUNE and JD+KD give similar bounds. We also show how much the bounds on the NUNM parameters can be improved by combining the prospective data from DUNE and JD+KD setups. We find that due to zero-distance effects, the near detectors alone can also constrain $α_{11}$, $|α_{21}|$, and $α_{22}$ in both these setups. Finally, we observe that the $ν_τ$ appearance sample in DUNE can improve the constraints on $|α_{32}|$ and $α_{33}$.

hep-ph↗

arXiv2022

Probing Lorentz Invariance Violation with Atmospheric Neutrinos at INO-ICAL

The possibility of Lorentz Invariance Violation (LIV) may appear in unified theories, such as string theory, which allow the existence of a new space-time structure at the Planck scale ($M_p \sim 10^{19}$ GeV). This effect can be observed at low energies with a strength of $\sim 1/M_p$ using the perturbative approach. In the minimal Standard Model extension (SME) framework, the neutrino mass-induced flavor oscillation gets modified in the presence of LIV. The Iron Calorimeter (ICAL) detector at the proposed India-based Neutrino Observatory (INO) offers a unique window to probe these LIV parameters by observing atmospheric neutrinos and antineutrinos separately over a wide range of baselines in the multi-GeV energy range. In this paper, for the first time, we study in detail how the CPT-violating LIV parameters $(a_{μτ}, a_{eμ}, a_{eτ})$ can alter muon survival probabilities and expected $μ^-$ and $μ^+$ event rates at ICAL. Using 500 kt$\cdot$yr exposure of ICAL, we place stringent bounds on these CPT-violating LIV parameters at 95\% C.L., which are slightly better than the present Super-Kamiokande limits. We demonstrate the advantage of incorporating hadron energy information and charge identification capability at ICAL while constraining these LIV parameters. Further, the impact of the marginalization over the oscillation parameters and choice of true values of $\sin^2θ_{23}$ on LIV constraints is described. We also study the impact of these LIV parameters on mass ordering determination and precision measurement of atmospheric oscillation parameters.

hep-ph↗

arXiv2021

A close look on 2-3 mixing angle with DUNE in light of current neutrino oscillation data

Recent global fit analyses of oscillation data show a preference for normal mass ordering (NMO) at 2.5$σ$ and provide 1.6$σ$ indications for lower $θ_{23}$ octant and leptonic CP violation. A high-precision measurement of $θ_{23}$ is pivotal to convert these hints into discoveries. In this work, we study in detail the capabilities of DUNE to establish the deviation from maximal $θ_{23}$ and to resolve its octant at high confidence levels. We exhibit the possible correlations and degeneracies among $\sin^2θ_{23}$, $Δm^2_{31}$, and $δ_{CP}$ in disappearance and appearance oscillation channels at the probability and event levels. Introducing for the first time, a bi-events plot in the plane of total $ν$ and $\barν$ disappearance events, we discuss the impact of $\sin^2θ_{23}$ - $Δm^2_{31}$ degeneracy in establishing non-maximal $θ_{23}$ and show how this degeneracy can be resolved by exploiting the spectral shape information in $ν$ and $\barν$ disappearance events. A 3$σ$ (5$σ$) determination of non-maximal $θ_{23}$ is possible in DUNE in total 7 years if $\sin^2θ_{23} \lesssim 0.465~(0.450)$ or $\sin^2θ_{23} \gtrsim 0.554~(0.572)$ for any value of $δ_{CP}$ and NMO. We study the individual contributions from appearance and disappearance channels, impact of systematic uncertainties and marginalization over oscillation parameters, importance of spectral analysis and data from both $ν$ and $\barν$ runs, while analyzing DUNE's sensitivity to establish non-maximal $θ_{23}$. DUNE can resolve the octant of $θ_{23}$ at 4.2$σ$ (5$σ$) using 7 (10) years of run assuming $\sin^2θ_{23}$ = 0.455, $δ_{CP}$ = $223^\circ$, and NMO. DUNE can improve the current relative 1$σ$ precision on $\sin^2θ_{23}$ ($Δm^2_{31}$) by a factor of 4.4 (2.8) using 7 years of run.

hep-ph↗

arXiv2021

Exploring Earth's Matter Effect in High-Precision Long-Baseline Experiments

The Earth's matter effect is going to play a crucial role in measuring the unknown three-flavor neutrino oscillation parameters at high confidence level in future high-precision long-baseline experiments. We observe that owing to the new degeneracies among the most uncertain oscillation parameters ($δ_{CP}, θ_{23}$) and the average Earth's matter density ($ρ_{avg}$) for the 1300 km baseline, the sensitivity of the upcoming Deep Underground Neutrino Experiment (DUNE) to establish Earth's matter effect reaches only about 2$σ$ C.L. for all possible choices of oscillation parameters. We notice that the current uncertainty in $δ_{CP}$ degrades the measurement of $ρ_{avg}$ more as compared to $θ_{23}$. To lift these degeneracies, we explore the possible complementarity between DUNE and Tokai to Hyper-Kamiokande (T2HK/JD) facility with a second detector in Korea, popularly known as T2HKK or JD+KD setup. While DUNE uses wide-band beam with on-axis detector, T2HKK setup plans to use narrow-band beam with two off-axis detectors: one in Japan and other in Korea. We exhibit how the high-precision measurement of $δ_{CP}$ in JD+KD setup and the information on $ρ_{avg}$ coming from DUNE can reduce the impact of these degeneracies in both ($ρ_{avg}-δ_{CP}$) and ($ρ_{avg}-θ_{23}$) planes. We show that the combined data from DUNE and JD+KD setups can establish Earth's matter effect at more than 6$σ$ C.L. irrespective of both the choices of mass hierarchy: normal (NH) and inverted (IH), $δ_{CP}$, and $θ_{23}$. With the help of this combined data set, we can measure the average matter density ($ρ_{avg}$) with a relative 1$σ$ precision of around 11.2% (9.4%) assuming true NH (IH) and $δ_{CP} = -90^{\circ}/90^{\circ}$.

hep-ph↗

arXiv2021

Probing the Earth's Core using Atmospheric Neutrinos at INO

The proposed 50 kt Iron Calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) aims to detect atmospheric muon neutrinos and antineutrinos separately in the multi-GeV range of energies and over a wide range of path lengths. While passing through the Earth, the upward-going neutrinos experience a density-dependent matter effect, which can be utilized to extract information about the internal structure of Earth. Since the Earth's matter effect modifies the neutrino oscillation patterns differently for neutrinos and antineutrinos, the capability of ICAL to distinguish $μ^-$ and $μ^+$ events plays an important role in observing this matter effect. Taking advantage of good angular resolution, ICAL would be able to observe about 331 $μ^-$ and 146 $μ^+$ events corresponding to the core-passing neutrinos and antineutrinos, respectively, in 10 years. We demonstrate for the first time that ICAL would be able to validate the presence of Earth's core by ruling out a two-layered profile consisting of only mantle and crust in fit with respect to the PREM profile in data with a median $Δχ^2$ of 7.45 for normal mass ordering (NO) and 4.83 for inverted mass ordering (IO) using 500 kt$\cdot$yr exposure. If we do not use the charge identification capability of ICAL, these sensitivities deteriorate to a $Δχ^2$ of 3.76 for NO and 1.59 for IO.

hep-ph↗

arXiv2021

Validating the Earth's Core using Atmospheric Neutrinos with ICAL at INO

The Iron Calorimeter (ICAL) detector at the proposed India-based Neutrino Observatory (INO) aims to detect atmospheric neutrinos and antineutrinos separately in the multi-GeV range of energies and over a wide range of baselines. By utilizing its charge identification capability, ICAL can efficiently distinguish $μ^-$ and $μ^+$ events. Atmospheric neutrinos passing long distances through Earth can be detected at ICAL with good resolution in energy and direction, which enables ICAL to see the density-dependent matter oscillations experienced by upward-going neutrinos in the multi-GeV range of energies. In this work, we explore the possibility of utilizing neutrino oscillations in the presence of matter to extract information about the internal structure of Earth complementary to seismic studies. Using good directional resolution, ICAL would be able to observe 331 $μ^-$ and 146 $μ^+$ core-passing events with 500 kt$\cdot$yr exposure. With this exposure, we show for the first time that the presence of Earth's core can be independently confirmed at ICAL with a median $Δχ^2$ of 7.45 (4.83) assuming normal (inverted) mass ordering by ruling out the simple two-layered mantle-crust profile in theory while generating the prospective data with the PREM profile. We observe that in the absence of charge identification capability of ICAL, this sensitivity deteriorates significantly to 3.76 (1.59) for normal (inverted) mass ordering.

hep-ph↗

arXiv2021

A New Approach to Probe Non-Standard Interactions in Atmospheric Neutrino Experiments

We propose a new approach to explore the neutral-current non-standard neutrino interactions (NSI) in atmospheric neutrino experiments using oscillation dips and valleys in reconstructed muon observables, at a detector like ICAL that can identify the muon charge. We focus on the flavor-changing NSI parameter $\varepsilon_{μτ}$, which has the maximum impact on the muon survival probability in these experiments. We show that non-zero $\varepsilon_{μτ}$ shifts the oscillation dip locations in $L/E$ distributions of the up/down event ratios of reconstructed $μ^-$ and $μ^+$ in opposite directions. We introduce a new variable $Δd$ representing the difference of dip locations in $μ^-$ and $μ^+$, which is sensitive to the magnitude as well as the sign of $\varepsilon_{μτ}$, and is independent of the value of $Δm^2_{32}$. We further note that the oscillation valley in the ($E$, $\cos θ$) plane of the reconstructed muon observables bends in the presence of NSI, its curvature having opposite signs for $μ^-$ and $μ^+$. We demonstrate the identification of NSI with this curvature, which is feasible for detectors like ICAL having excellent muon energy and direction resolutions. We illustrate how the measurement of contrast in the curvatures of valleys in $μ^-$ and $μ^+$ can be used to estimate $\varepsilon_{μτ}$. Using these proposed oscillation dip and valley measurements, the achievable precision on $|\varepsilon_{μτ}|$ at 90% C.L. is about 2% with 500 kt$\cdot$yr exposure. The effects of statistical fluctuations, systematic errors, and uncertainties in oscillation parameters have been incorporated using multiple sets of simulated data. Our method would provide a direct and robust measurement of $\varepsilon_{μτ}$ in the multi-GeV energy range.

hep-ph↗

arXiv2021

Probing NSI in Atmospheric Neutrino Experiments using Oscillation Dip and Valley

We propose a new approach to probe neutral-current non-standard neutrino interaction parameter $\varepsilon_{μτ}$ using the oscillation dip and oscillation valley. Using the simulated ratio of upward-going and downward-going reconstructed muon events at the upcoming ICAL detector, we demonstrate that the presence of non-zero $\varepsilon_{μτ}$ would result in the shift in the dip location as well as the bending of the oscillation valley. Thanks to the charge identification capability of ICAL, the opposite shifts in the locations of oscillation dips as well as the contrast in the curvatures of oscillation valleys for $μ^-$ and $μ^+$ is used to constrain $|\varepsilon_{μτ}|$ at 90% C.L. to about 2% using 500 kt$\cdot$yr exposure. Our procedure incorporates statistical fluctuations, uncertainties in oscillation parameters, and systematic errors.

hep-ph↗

arXiv2021

Evolution of Neutrino Mass-Mixing Parameters in Matter with Non-Standard Interactions

We explore the role of matter effect in the evolution of neutrino oscillation parameters in the presence of lepton-flavor-conserving and lepton-flavor-violating neutral-current non-standard interactions (NSI) of the neutrino. We derive simple approximate analytical expressions showing the evolution/running of mass-mixing parameters in matter with energy in the presence of standard interactions (SI) and SI+NSI (considering both positive and negative values of real NSI parameters). We observe that only the NSI parameters in the (2,3) block, namely $\varepsilon_{μτ}$ and $(γ- β) \equiv (\varepsilon_{ττ} - \varepsilon_{μμ})$ affect the running of $θ_{23}$. Though all the NSI parameters influence the evolution of $θ_{13}$, $\varepsilon_{eμ}$ and $\varepsilon_{eτ}$ show a stronger impact at the energies relevant for DUNE. $θ_{12}$ quickly approaches to $\sim$ $90^{\circ}$ with increasing energy in both SI and SI+NSI cases. The change in $Δm^2_{21,m}$ is quite significant as compared to $Δm^2_{31,m}$ both in SI and SI+NSI frameworks. Flipping the signs of the NSI parameters alters the way in which mass-mixing parameters run with energy. We demonstrate the utility of our approach in addressing several important features related to neutrino oscillation such as: a) unraveling interesting degeneracies between $θ_{23}$ and NSI parameters, b) estimating the resonance energy in presence of NSI when $θ_{13}$ in matter becomes maximal, c) figuring out the required baselines and energies to have maximal matter effect in $ν_μ$ $\rightarrow$ $ν_{e}$ transition in the presence of different NSI parameters, and d) studying the impact of NSI parameters $\varepsilon_{μτ}$ and $(γ- β)$ on the $ν_μ \to ν_μ$ survival probability.

hep-ph↗

arXiv2021

Can Lorentz Invariance Violation affect the Sensitivity of Deep Underground Neutrino Experiment?

We examine the impact of Lorentz Invariance Violation (LIV) in measuring the octant of $θ_{23}$ and CP phases in the context of the Deep Underground Neutrino Experiment (DUNE). We consider the CPT-violating LIV parameters involving $e - μ$ ($a_{eμ}$) and $e - τ$ ($a_{eτ}$) flavors, which induce an additional interference term in neutrino and antineutrino appearance probabilities. This new interference term depends on both the standard CP phase $δ$ and the new dynamical CP phase $φ_{eμ}$/$φ_{eτ}$, giving rise to new degeneracies among ($θ_{23}$, $δ$, $φ$). Taking one LIV parameter at-a-time and considering a small value of $|a_{eμ}| = |a_{eτ}| = 5 \times 10^{-24}$ GeV, we find that the octant discovery potential of DUNE gets substantially deteriorated for unfavorable combinations of $δ$ and $φ_{eμ}$/$φ_{eτ}$. The octant of $θ_{23}$ can only be resolved at $3σ$ if the true value of $\sin^2θ_{23} \lesssim 0.42$ or $\gtrsim 0.62$ for any choices of $δ$ and $φ$. Interestingly, we also observe that when both the LIV parameters $a_{eμ}$ and $a_{eτ}$ are present together, they cancel out the impact of each other to a significant extent, allowing DUNE to largely regain its octant resolution capability. We also reconstruct the CP phases $δ$ and $φ_{eμ}$/$φ_{eτ}$. The typical $1σ$ uncertainty on $δ$ is $10^{\circ}$ to $15^{\circ}$ and the same on $φ_{eμ}$/$φ_{eτ}$ is $25^{\circ}$ to $30^{\circ}$ depending on the choices of their true values.

hep-ph↗

arXiv2021

From oscillation dip to oscillation valley in atmospheric neutrino experiments

Atmospheric neutrino experiments can show the "oscillation dip" feature in data, due to their sensitivity over a large $L/E$ range. In experiments that can distinguish between neutrinos and antineutrinos, like INO, oscillation dips can be observed in both these channels separately. We present the dip-identification algorithm employing a data-driven approach -- one that uses the asymmetry in the upward-going and downward-going events, binned in the reconstructed $L/E$ of muons -- to demonstrate the dip, which would confirm the oscillation hypothesis. We further propose, for the first time, the identification of an "oscillation valley" in the reconstructed ($E_μ$,$\,\cosθ_μ$) plane, feasible for detectors like ICAL having excellent muon energy and direction resolutions. We illustrate how this two-dimensional valley would offer a clear visual representation and test of the $L/E$ dependence, the alignment of the valley quantifying the atmospheric mass-squared difference. Owing to the charge identification capability of the ICAL detector at INO, we always present our results using $μ^{-}$ and $μ^{+}$ events separately. Taking into account the statistical fluctuations and systematic errors, and varying oscillation parameters over their currently allowed ranges, we estimate the precision to which atmospheric neutrino oscillation parameters would be determined with the 10-year simulated data at ICAL using our procedure.

hep-ph↗

arXiv2019

Physics Potential of ESS$ν$SB in the presence of a Light Sterile Neutrino

ESS$ν$SB is a proposed neutrino super-beam project at the ESS facility. We study the performance of this setup in the presence of a light eV-scale sterile neutrino, considering 540 km baseline with 2 years (8 years) of $ν$ ($\barν$) run-plan. This baseline offers the possibility to work around the second oscillation maximum, providing high sensitivity towards CP-violation (CPV). We explore in detail its capability in resolving CPV generated by the standard CP phase $δ_{13}$, the new CP phase $δ_{14}$, and the octant of $θ_{23}$. We find that the sensitivity to CPV induced by $δ_{13}$ deteriorates noticeably when going from $3ν$ to 4$ν$ case. The two phases $δ_{13}$ and $δ_{14}$ can be reconstructed with a 1$σ$ uncertainty of $\sim15^0$ and $ \sim35^0$ respectively. Concerning the octant of $θ_{23}$, we find poor sensitivity in both $3ν$ and $4ν$ schemes. Our results show that a setup like ESS$ν$SB working around the second oscillation maximum with a baseline of 540 km, performs quite well to explore CPV in 3$ν$ scheme, but it is not optimal for studying CP properties in 3+1 scheme.

hep-ph↗