arXiv subjects

Rudra Majhi

Publications and source records attributed to Rudra Majhi.

14 recordsLinked to original sources

arXiv2026

Impact of different neutrino decoherence formalisms at the future long-baseline Experiments

In this paper, we have studied the impact of two different formalisms of quantum decoherence in determining the sensitivities of the two future long-baseline experiments DUNE and P2SO. In formalism-A, we will assume that the decoherence matrix is defined in a matter mass eigenstate basis which is the basis that diagonalizes the Hamiltonian for neutrinos in matter, with a constant matter density. In formalism-B, we will define the decoherence matrix in the vacuum mass eigenstate basis and then rotate it to matter mass basis via an unitary transformation. By using different values of the decoherence parameter $Γ$, we will show how these two formalisms differ at the probability level and then we will demonstrate how the sensitivities can differ at the $χ^2$ level. Our results show that if the values of $Γ$ are small, then these two formalisms yield same probability in vacuum. However, if the values of $Γ$ is large or if there is strong matter effect, then these two formalisms yield very different results.

hep-ph↗

arXiv2026

A Predictive Non-Holomorphic Modular $A_4$ Linear Seesaw Framework Testable at DUNE

We study a realization of neutrino masses and mixing phenomena within a linear seesaw mechanism based on non-holomorphic modular $A_4$ symmetry, which extends modular-invariant flavor models beyond the conventional holomorphic framework. The model is constructed in a non-supersymmetric setting and involves six heavy $SU(2)_L$ singlet fermions, $N_{Ri}$ and $S_{Li}$, together with a single flavon field, thereby significantly reducing the field content compared to conventional $A_4$ flavor models that typically require multiple flavon fields as well as supersymmetric (holomorphic) modular frameworks involving additional superfields. The modular transformation properties of the Yukawa couplings under $A_4$ symmetry lead to a highly constrained neutrino mass matrix with a distinctive flavor structure. After presenting the general theoretical framework, we perform a systematic numerical analysis of neutrino phenomenology by restricting the modulus parameter $τ$ to the fundamental domain and scanning the allowed parameter space. We identify regions consistent with current neutrino oscillation data at the $3σ$ level and obtain predictions for currently unknown observables, including the absolute neutrino mass scale and leptonic CP-violating phases. We further examine the implications for neutrinoless double beta decay, highlighting testable signatures in the upcoming precision oscillation as well as rare-process experiments. These results demonstrate the phenomenological viability and predictive power of non-holomorphic modular symmetry in linear seesaw neutrino mass models.

hep-ph↗

arXiv2026

Exploring supernova neutrino mass ordering at DUNE via quantum entanglement

The Deep Underground Neutrino Experiment (DUNE) offers strong sensitivity to neutrinos from a Galactic core collapse supernova, providing a powerful probe of neutrino flavor conversion and the neutrino mass ordering. In this work, we study supernova neutrino oscillations at DUNE using quantum entanglement as an organizing framework. Treating the three flavor neutrino system as an effective multipartite quantum state, we quantify flavor correlations through the entanglement of formation, concurrence, and negativity, expressed directly in terms of flavor survival and transition probabilities. Benchmark scenarios defined by representative variations of the electron neutrino survival probability are constructed for each entanglement measure. Event rates and fluences are computed for a supernova at 10 kpc, and the mass ordering sensitivity is evaluated using detector-level simulations performed with the \texttt{SNOwGLoBES} framework, employing the Garching supernova flux model and including the dominant detection channels in liquid argon: $ν_e$ and $\barν_e$ charged-current interactions on argon and elastic scattering on electrons. We analyze both individual and combined detection channels and incorporate $5\%$ normalization and energy calibration systematic uncertainties. Our results show that DUNE achieves a $5σ$ determination of the neutrino mass ordering for a supernova at distances of $\sim 20$~kpc for the $ν_e$ charged current channel and $\sim 2$~kpc for the $\barν_e$ channel, with the reach depending on the entanglement scenario considered. These results demonstrate that entanglement based observables provide a complementary and robust framework for probing supernova neutrino oscillations and the neutrino mass ordering.

hep-ph↗

arXiv2025

On Critical Temperature and Finite Size Scaling of Continuous Spin $2d$ Ising Model

In this paper, we have studied the critical temperature $T_c$ of continuous spin $2d$ square-lattice Ising model using Monte-Carlo simulation. We have considered spins $s$ in a bounded interval, where $s \in [-1,+1]$ in square-lattice configuration with periodic boundary condition. We have observed that the critical temperature $T_c$ is approximately $0.925$, showing a clear second order phase transition. Considering finite size scaling, we have also obtained the critical exponents associated with susceptibility, specific heat, magnetization and we find that these values are in good agreement with the corresponding values obtained for the standard $2d$ Ising universality class.

cond-mat.stat-mech↗

arXiv2025

Impact of scalar NSI with off-diagonal parameters at DUNE and P2SO

In this paper, we studied the impact of the off-diagonal SNSI parameters in the future long-baseline neutrino oscillation experiments DUNE and P2SO. In our analysis, we found that the sensitivities of these experiments altered in a very non-trivial way due to the presence of these parameters. Depending on the values of these parameters, they can either completely mimic the standard scenario or can wash out their CP sensitivity. For large values of parameters $η_{eμ}$ and $η_{eτ}$, we obtained larger mass ordering and octant sensitivities as compared to the standard three flavour scenario. For the parameter $η_{μτ}$, the mass ordering sensitivity and the precision of $Δm^2_{31}$ deteriorated compared to the standard scenario. Our results also showed that the sensitivities were significantly influenced by the phases of the off-diagonal parameters.

hep-ph↗

arXiv2024

Study of Long Range Force in P2SO and T2HKK

In this paper we have studied the sensitivity of the future long-baseline neutrino experiments P2SO and T2HKK to the long-range force (LRF). In the context of these two experiments, our aim is to study: (i) the capability to put bounds on the LRF parameters, (ii) effect of LRF in the measurement of standard oscillation parameters and (iii) capability to constrain the mass of the new gauge boson and the value of new coupling constant, that gives rise to LRF due to matter density in Sun. In our study, we find that among the different neutrino experiments, the best bound on the LRF parameters including mass of the new gauge boson and the value of new coupling constant will come from the P2SO experiment. Our study also shows that LRF has non-trivial effect on the determination of the standard neutrino oscillation parameters except the precision of $Δm^2_{31}$. For this parameter, the precision remains unaltered in the presence of LRF for both these experiments.

hep-ph↗

arXiv2024

Study of Scalar Non Standard Interaction at Protvino to Super-ORCA experiment

In this paper we have studied the phenomenon of non-standard interaction mediated by a scalar field (SNSI) in the context of P2SO experiment and compared its sensitivity with DUNE. In particular, we have studied the capability of these two experiments to put bounds on the diagonal SNSI parameters i.e., $η_{ee}$, $η_{μμ}$ and $η_{ττ}$ and studied the impact of these parameters on the determination of neutrino mass ordering, octant of $θ_{23}$ and CP violation (CPV). In our analysis we find that, the parameter $Δm^2_{31}$ has a non-trivial role if one wants estimate the bounds on $η_{μμ}$ and $η_{ττ}$ assuming SNSI does not exist in nature. Our results show that sensitivity of P2SO and DUNE to constraint $η_{μμ}$ and $η_{ττ}$ are similar whereas the sensitivity of DUNE is slightly better for $η_{ee}$. We find that the mass ordering and CPV sensitivities are mostly affected by $η_{ee}$ compared to $η_{μμ}$ and $η_{ττ}$ if one assumes SNSI exists in nature. On the other hand, octant sensitivity is mostly affected by $η_{μμ}$ and $η_{ττ}$. These sensitivities can be either higher or lower than the standard three flavour scenario depending on the relative sign of the SNSI parameters. Regarding the precision of atmospheric mixing parameters, we find that the precision of $θ_{23}$ deteriorates significantly in the presence of $η_{μμ}$ and $η_{ττ}$.

hep-ph↗

arXiv2023

Distinguishing Non-Standard Interaction and Lorentz Invariance Violation at Protvino to Super-ORCA experiment

As the two phenomena, non-standard interaction (NSI) in neutrino propagation and Lorentz invariance violation (LIV) modify the Hamiltonian of neutrino oscillation in a similar fashion, it is very difficult to distinguish these two effects. The only difference between them lies in the fact that NSI depends on the matter density, whereas LIV is independent of the earth matter effect. Therefore for a fixed baseline experiment, where matter density is constant, the theories describing NSI and LIV are exactly equivalent. However, as the present and future bounds of the NSI and LIV parameters are not equivalent, one can distinguish these two scenarios in the long-baseline neutrino experiments depending on their statistics with respect to the present and future bounds of these parameters. In this paper, we attempt to differentiate between LIV and NSI in the context of DUNE and P2SO, as these two future experiments are believed to be sensitive to the strongest matter effect and will have very large statistics. Taking LIV in the data and NSI in theory, our results show that, indeed it is possible to have good discrimination between LIV and NSI. The best separation between LIV and NSI at $3 σ$ C.L. is achieved for the parameter $a_{μμ}$ with P2SO. In this case, the value of LIV parameter for which separation is possible, lies within its future bound, if one considers the value of NSI parameter to be constrained by the present experiments. Between DUNE and P2SO, the latter has better sensitivity for such discrimination.

hep-ph↗

arXiv2023

Study of light sterile neutrino at the long-baseline experiment options at KM3NeT

In this paper, we study the capability of different long-baseline experiment options at the KM3NeT facility i.e., P2O, Upgraded P2O and P2SO to probe the light sterile neutrino and compare their sensitivities with DUNE. The P2O option will have neutrinos from a 90 KW beam at Protvino to be detected at the ORCA detector, the Upgraded P2O will have neutrinos from the upgraded 450 KW beam to be detected at the ORCA detector and the option P2SO will have neutrinos from a 450 KW beam to be detected at the upgraded Super-ORCA detector. All these options will have a baseline around 2595 km. Our results show that the experiments at the KM3NeT (DUNE) would be more sensitive if the value of $Δm^2_{41}$ is around 10 (1) eV$^2$. Our results also show that the role of near detector is very important for the study of sterile neutrinos and addition of near detector improves the sensitivity as compared to only far detector for 3+1 scenario. Among the three options at KM3NeT, the sensitivity of P2O and upgraded P2O is limited and sensitivity of P2SO is either comparable or better than DUNE.

hep-ph↗

arXiv2022

Vector leptoquark $U_3$ and CP violation at T2K, NOvA experiments

In the current epoch of neutrino physics, many experiments are aiming for precision measurements of oscillation parameters. Thus, various new physics scenarios which alter the neutrino oscillation probabilities in matter deserve careful investigation. In this context, we study the effect of a vector leptoquark which induces non-standard neutrino interactions (NSI) that modify the oscillation probabilities of neutrinos in matter. We show that such interactions provide a relatively large value of NSI parameter $\varepsilon_{e μ}$. Considering this NSI parameter, we successfully explain the recent discrepancy between the observed $δ_{CP}$ results of T2K and NOvA.

hep-ph↗

arXiv2022

Optimal configuration of Protvino to ORCA experiment for hierarchy and non-standard interactions

In this paper, we study the hierarchy sensitivity of Protvino to ORCA (P2O) experiment in three flavour scenario as well as its sensitivity to non-standard interactions (NSI) in neutrino propagation. Because of the largest possible baseline length of 2595 km, P2O is expected to have strong sensitivity towards neutrino mass hierarchy and NSI parameters. In our study, we show that even though the number of appearance channel events for the minimal configuration of P2O are higher compared to DUNE, still the hierarchy sensitivity of P2O is less than DUNE because of large background events. Our results show that for a background reduction factor of 0.46 and appearance channel background systematic normalization error of $4\%$, the hierarchy sensitivity of P2O becomes equivalent of DUNE for $δ_{\rm CP} = 195^\circ$. We call this configuration of P2O as optimized P2O. Regarding the study of NSI, we find that, for $ε_{eμ}$ ($ε_{eτ}$) sensitivity of DUNE is similar (better) as compared to optimized P2O when both $ε_{eμ}$ and $ε_{eτ}$ are included in the analysis. Our results show that in presence of NSI, the change of hierarchy sensitivity with respect to standard three flavor scenario, is higher in P2O as compared to DUNE. Further, hierarchy sensitivity in presence of NSI is lower (higher) than sensitivity in the standard three flavour scenario for $δ_{\rm CP} = 270^\circ (90^\circ)$. It is important to note that hierarchy sensitivity of optimized P2O does not get significantly better than DUNE for the current favourable values of $δ_{\rm CP}$ which is $180^\circ < δ_{\rm CP} < 360^\circ$ as obtained by the global analysis in both standard three flavour and in presence of NSI.

hep-ph↗

arXiv2021

Constraining CPT violation with Hyper-Kamiokande and ESSnuSB

CPT invariance is one of the most fundamental symmetries in nature and it plays a major role in the formulation of Quantum Field Theory. Although no definitive signal of CPT violation has been observed so far, there are many reasons to carefully investigate various low-energy phenomena that can provide better probes to test CPT symmetry. In this context, neutrino experiments are expected to provide more stringent bounds on CPT invariance violation when compared to the existing bounds from the Kaon system. In this work, we investigate the sensitivity of the upcoming long-baseline experiments: Hyper Kamiokande (T2HK, T2HKK), ESSnuSB and DUNE to constrain the CPT violating parameters $Δ(δ_{CP})$, $Δ(m^2_{31})$ and $Δ(\sin^2 θ_{23})$, which characterize the difference between neutrino and antineutrino oscillation parameters. Further, we analyse neutrino and antineutrino data independently and constrain the oscillation parameters governing them by considering the combination of these experiments (DUNE+T2HKK and DUNE+ESSnuSB). In addition, assuming CPT symmetry is violated in nature, we study the individual ability of the aforementioned experiments to establish CPT violation. We found that the experiments Hyper-K (T2HK, T2HKK) and ESSnuSB, along with DUNE, will be able to establish CPT violation in their proposed run-times.

hep-ph↗

arXiv2020

Light sterile neutrinos and their implications on currently running long-baseline and neutrinoless double beta decay experiments

Recent $ν_e$ appearance data from the Mini Booster Neutrino Experiment (MiniBooNE) are in support of the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND), which provides an indirect hint for the existence of eV-scale sterile neutrino. As these sterile neutrinos can mix with the standard active neutrinos, in this paper we explore the effect of such active-sterile mixing on the determination of various oscillation parameters by the currently running long-baseline neutrino experiments T2K and NO$ν$A. We find that the existence of sterile neutrino can lead to new kind of degeneracies among these parameters which would substantially deteriorate the mass hierarchy sensitivity of NO$ν$A experiment. We further notice that the inclusion of data from T2K experiment helps in resolving the degeneracies. The impact of new CP violating phases $δ_{14}$ and $δ_{34}$ on the maximal CP-violation exclusion sensitivity for NO$ν$A experiment has also been illustrated. Finally, we discuss the implication of such light sterile neutrinos on neutrinoless double beta decay processes in line with recent experimental results, as well as on the sensitivity reach of future experiments.

hep-ph↗

arXiv2020

Exploring the effect of Lorentz invariance violation with the currently running long-baseline experiments

Neutrinos are the fundamental particles, blind to all kind of interactions except the weak and gravitational. Hence, they can propagate very long distances without any deviation. This characteristic property can thus provide an ideal platform to investigate Planck suppressed physics through their long distance propagation. In this work, we intend to investigate CPT violation through Lorentz invariance violation (LIV) in the long-baseline accelerator based neutrino experiments. Considering the simplest four-dimensional Lorentz violating parameters, for the first time, we obtain the sensitivity limits on the LIV parameters from the currently running long-baseline experiments T2K and NO$ν$A. In addition to this, we show their effects on mass hierarchy and CP violation sensitivities by considering NO$ν$A as a case study. We find that the sensitivity limits on LIV parameters obtained from T2K are much weaker than that of NO$ν$A and the synergy of T2K and NO$ν$A can improve these sensitivities. All these limits are slightly weaker ($2 σ$ level) compared to the values extracted from Super-Kamiokande experiment with atmospheric neutrinos. Moreover, we observe that the mass hierarchy and CPV sensitivities are either enhanced or deteriorated significantly in the presence of LIV as these sensitivities crucially depend on the new CP-violating phases. We also present the correlation between $\sin^2 θ_{23}$ and the LIV parameter $|a_{αβ}|$, as well as $δ_{CP}$ and $|a_{αβ}|$.

hep-ph↗