arXiv subjects

Rukmani Mohanta

Publications and source records attributed to Rukmani Mohanta.

At least 19 recordsLinked to original sources

arXiv2026

Phenomenology of different cross-section models at DUNE

In this paper, we study the impact of different cross-section models in the measurement of the neutrino oscillation parameters in DUNE. In particular, for the quasi-elastic (QEL) region, we considered the Llewellyn-Smith formalism (LS) and the Hartree-Fock Continuum Random Phase Approximation (HF-CRPA) and for the resonance (RES) region, we consider the Rein-Sehgal (RS) and the Berger-Sehgal (BS) models, and compare our results with the DUNE cross-section tune (Valencia model for QEL and RS model for RES), which was considered in their technical design report. Our results show that while the DUNE tune is best for QEL, the best model for RES is BS. As the DUNE energy region is mainly dominated by RES, for the total cross-section, the HF-CRPA+BS model provides the best strength in the cross-section, whereas the DUNE tune is the weakest among all the configurations considered in our work. Regarding the neutrino mass ordering, CP violation and octant sensitivity, the HF-CRPA+BS model provides $(25- 30)$% improvement, and regarding the precision of the $θ_{23}$ and $Δm^2_{32}$, the same model provides $(15 - 20)$% improvement as compared to the DUNE tune.

hep-ph↗

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

Probing mixed-state dark matter and flavor observables in a scalar-assisted baryonic gauge theory

We explore a {standard model} extension based on a local $U(1)_B$ symmetry, where a baryon-charged scalar mediates interactions between a fermionic dark matter candidate and {standard model} quarks. In this setup, the dark matter relic abundance is shaped not only by standard annihilation channels but also by additional coannihilation processes induced by a new scalar. The presence of this mediator provides a unified link between {dark sector} and flavor physics, yielding distinctive phenomenological consequences. We conduct a detailed study of dark matter phenomenology, emphasizing the role of the mass splitting between the dark matter particles and the scalar mediator in determining the efficiency of coannihilation. The parameter space is examined in light of existing constraints from cosmological observations, direct and indirect detection experiments, as well as the collider searches at the {\text{LHC}}. Our analysis shows that the extended scalar sector opens up viable regions of parameter space beyond those accessible in minimal $U(1)_B$ realizations, many of which are expected to be tested by forthcoming searches at {\text{XENONnT}} and {the \text{Cherenkov Telescope Array}}. Moreover, the model induces correlated signatures from flavor observables associated with the $b \to s $ transitions as well, serving as complementary tests of the underlying framework.

hep-ph↗

arXiv2026

Probing non-unitarity of the PMNS matrix in P2SO and comparison with DUNE

We compare the sensitivity of the upcoming long-baseline neutrino experiments Protvino to Super-ORCA (P2SO) and the Deep Underground Neutrino Experiment (DUNE) to non-unitarity (NU) of the leptonic mixing matrix in a model-independent framework. NU can arise in theories beyond the Standard Model that include heavy neutral leptons. These effects can modify neutrino oscillation probabilities and introduce new sources of CP violation, which may affect precision measurements of neutrino parameters. We find that DUNE provides stronger bounds on $α_{11}$ and $|α_{21}|$, while P2SO shows better sensitivity to $α_{22}$ and $α_{33}$, mainly due to its longer baseline and stronger matter effects. Our results show that DUNE (P2SO) will be able to improve the current bounds of $α_{11}$ ($α_{33}$). We further examine correlations with standard oscillation parameters and quantify the impact of NU on mass hierarchy, octant, and CP-violation sensitivities. Our results show that these sensitivities depend upon NU in a non-trivial way interconnecting the parameter degeneracies and matter effects. Our results demonstrate the complementarity of P2SO and DUNE in probing NU and show that NU can significantly influence next-generation precision oscillation studies.

hep-ph↗

arXiv2026

Gravitational Wave Signatures of $\mathrm{U(1)_X}$ Breaking and Right-Handed Neutrino Dynamics

The Standard Model (SM) leaves several fundamental questions unanswered, including the origin of neutrino masses, the baryon asymmetry of the Universe, and the nature of dark matter. Motivated by these gaps, we investigate an extension of the SM with an additional local $U(1)_X$ gauge symmetry and a complex scalar singlet that spontaneously breaks this symmetry via its vacuum expectation value. The extended framework naturally accommodates three right-handed neutrinos (RHNs) to ensure anomaly cancellation and implements a type-I seesaw mechanism for active neutrino masses. We utilized Casas-Ibarra parameterization to systematically reconstruct the Yukawa coupling matrix which automatically satisfy the observed neutrino data. Furthermore, we estimate the key parameters of the first-order phase transition and compute the resulting stochastic gravitational wave spectrum, demonstrating that it can lie within the reach of forthcoming experiments such as LISA, DECIGO, BBO, and the Einstein Telescope. The right-handed neutrinos also open a viable path for thermal leptogenesis, providing a unified link between neutrino mass generation, baryogenesis, and gravitational wave signatures. Our results demonstrate that this minimal $U(1)_X$ scenario remains a promising probe for physics beyond the Standard Model, accessible through upcoming gravitational wave and neutrino experiments.

hep-ph↗

arXiv2026

Role of heavy neutral lepton in lepton number violating $B$ meson decays

We study the phenomenology of heavy neutral leptons (HNLs) in $B$-meson decays as probes of physics beyond the Standard Model. Focusing on the leptonic channels $B \to μN$ and $B \to τN$, we constrain the allowed regions in the $M_N$--$|U_{\ell N}|^2$ plane using current experimental data. Using these constraints, we investigate lepton-number violating ($ΔL=2$) processes mediated by on-shell HNLs, including $B_{(c)}^- \to π^+ μ^- μ^-$ and $B_c^- \to J/ψ\, π^+ μ^- μ^-$. For benchmark values $|U_{μN}|^2 = 10^{-6}$ and $M_N = 2$-- $3\,\mathrm{GeV}$, the predicted branching ratios lie in the range $\mathcal{O}(10^{-13})$--$\mathcal{O}(10^{-8})$. Among the channels, $B_c^- \to π^+ μ^- μ^-$ shows the largest enhancement, while $B_c^- \to J/ψ\, π^+ μ^- μ^-$ is strongly suppressed. These results indicate a clear channel dependence, with $B_c$ modes providing enhanced sensitivity to HNL effects and offering promising avenues for future searches of lepton number violation.

hep-ph↗

arXiv2026

Correlative study of flavor anomalies and dark matter in the light of scalar leptoquark

We explore $U(1)_{L_e-L_μ}$ gauge extension of the Standard Model with particle content enlarged by three neutral fermions, of which the lightest one contributes to dark matter content of the Universe. The scalar sector is enriched with a $\tilde{R}_2$ scalar leptoquark doublet to investigate flavor anomalies in $B$-meson sector, an additional inert scalar doublet to realize neutrino mass at one loop and a scalar singlet to spontaneously break the new $U(1)$. We discuss dark matter relic density and direct detection cross section in scalar and gauge portals. New physics contribution for $b \to s$ transition comes from penguin diagrams with $Z^\prime$, leptquark and new fermions. We analyze the constraints on the model parameters from the established observables of $B \to K^{(*)} μ^+ μ^-$ and $B_s\to ϕμ^+ μ^-$ decay channels. Utilizing the permissible parameter space consistent with both flavor and dark sectors, we discuss the impact on various observables such as branching ratio, forward-backward asymmetry, longitudinal polarisation asymmetry, and also lepton non-universality of $Λ_b \to Λ^* (1520) (\to pK) \ell ^+\ell ^-$ decay channel.

hep-ph↗

arXiv2026

Effect of Off-diagonal NSI Parameters on Entanglement Measurements in Neutrino Oscillations

In this work, we explore the influence of off-diagonal non-standard interaction (NSI) parameters on quantum entanglement within the three-flavor neutrino oscillation framework. By expressing three key entanglement measures: Entanglement of Formation (EOF), Concurrence, and Negativity in terms of oscillation probabilities, we analyze how these quantum correlations are affected by the NSI parameters $ε_{eμ}$, $ε_{eτ}$, and $ε_{μτ}$, including their complex phases. The quantum correlation measures considered in this work cannot be extracted directly from event rates, but solely in terms of oscillation probabilities. Using the DUNE experiment as a reference point, our analysis shows that NSI effects are most pronounced at lower energies, while Negativity continuing to dominate even at higher energies. It is observed that $ε_{e μ}$ and $ε_{e τ}$ affect entanglement measures mainly through the appearance channel, while the impact of $ε_{μτ}$ on EOF, Concurrence, and Negativity is predominantly linked to the disappearance channel. Further, our results show that Negativity is more sensitive than EOF and Concurrence in the [Energy ($E$) - $δ_{CP}$] plane under the influence of off-diagonal NSI scenarios, displaying a clear dependence of the CP-violating phase, $δ_{CP}$ on specific energy ranges, particularly in the lower energy regime.

hep-ph↗

arXiv2026

Neutrino Fluence influenced by Memory Burdened Primordial Black Holes

We study the impact of quantum gravitational memory burden - a backreaction effect that suppresses black hole evaporation - on neutrino signals from primordial black holes (PBHs). This suppression, modeled via a parameter k, reduces the high-energy muon neutrino fluence, particularly during the late stages of evaporation. We also consider beyond the Standard Model scenarios in which heavy neutral leptons (HNLs) are emitted by PBHs and subsequently decay, injecting secondary neutrinos that partially mitigate the suppression in the MeV-GeV range. We compute the full time-integrated neutrino spectrum and evaluate the expected IceCube event rates across the (k, mN) parameter space. We analyze both single source burst scenarios and the cumulative Galactic contribution assuming PBHs trace a realistic dark matter halo distribution. Even under optimistic proximity assumptions, the predicted event rates remain far below IceCube sensitivity, and population-level stacking within current observational bounds on the PBH abundance does not yield an observable signal in the considered mass range for PBH abundances consistent with existing observational constraints. These results demonstrate that entropy-suppressed evaporation substantially weakens neutrino detectability of light PBHs and must be consistently incorporated in future multi-messenger searches.

hep-ph↗

arXiv2026

Quantum speed limit time for bipartite entanglement in neutrino oscillations in matter with non-standard interactions

In the three-flavor neutrino oscillation framework, we investigate the transition probabilities of an initial muon neutrino flavor state in the presence of non-standard interactions (NSIs) characterized by complex off-diagonal ($|ε_{αβ}|e^{iϕ_{αβ}}$) and diagonal parameters ($|ε_{αα}-ε_{ββ}|$), including a CP-violating phase and a constant matter potential, under both normal (NO) and inverted mass ordering (IO) scenarios. Within these scenarios and through the lens of mode entanglement, bipartite entanglement measures such as entanglement entropy and capacity of entanglement are quantified in terms of the transition probabilities, which can be measured in neutrino oscillation experiments. Using these two bipartite entanglement measures, we further explore the quantum speed limit (QSL) time, which describes how rapidly bipartite entanglement evolves during neutrino oscillations. We illustrate our results using the baseline lengths and energies corresponding to ongoing long-baseline accelerator neutrino experiments, such as T2K, NO$ν$A, and the upcoming DUNE experiment. In the presence of a CP-violating phase and a constant matter potential, both with and without NSI effects, we compare the QSL time behavior for bipartite entanglement in neutrino oscillations for NO and IO. The most pronounced discrepancies in the QSL time for bipartite entanglement arise from the off-diagonal NSI parameter $ε_{μτ}$ across both the NO and IO scenarios. We emphasize that among all the experiments considered, NO$ν$A and DUNE exhibit a rapid suppression of bipartite entanglement in neutrino oscillations in the standard oscillation scenario with NO at the end of their baseline lengths for the corresponding best-fit value of CP-violating phase. Our results hint at a possible imprint of new physics in neutrino oscillations.

hep-ph↗

arXiv2025

Analysis of neutrino oscillation parameters in the light on quantum entanglement

Numerous neutrino experiments have confirmed the phenomenon of neutrino oscillation, providing direct evidence of the quantum mechanical nature of neutrinos. In this work, we investigate the entanglement properties of neutrino flavor states within the framework of three-flavor neutrino oscillation using two major entanglement measures: entanglement of formation (EOF) and concurrence, utilizing the DUNE experimental setup. Our findings indicate that the maximally entangled state appears between $ν_μ$ and $ν_τ$ whereas, $ν_{e}$ behaves as a nearly separable state. To further explore the nature of bipartite entanglement, we introduce the concept of the monogamy of entanglement, which allows us to investigate the distinction between genuine three-flavor entanglement and bipartite entanglement. Our analysis confirms that the three-flavor neutrino system forms a bipartite entanglement structure, adhering to the Coffman-Kundu-Wootters (CKW) inequality. Additionally, we implement a minimization procedure to find the best-fit values of the oscillation parameters that correspond to the concurrence minima at the two specific energy points where the concurrence reaches its lowest values. Using these best-fit values, we probe three fundamental unknowns in neutrino oscillation: CP violation sensitivity, neutrino mass hierarchy, and the octant issue of $θ_{23}$, across two distinct energy points. Our results manifest that while the best-fit values obtained through concurrence minimization show slightly reduced sensitivity to CP violation compared to current best-fit values, they exhibit greater sensitivity to the mass hierarchy. Furthermore, the study reveals a maximal mixing angle for the atmospheric sector.

hep-ph↗

arXiv2025

Imprints of new physics operators in the semileptonic $B \to a_1 (1260) \ell^- \barν_\ell$ process in SMEFT approach

At present, there are several measurements of $B$ decays that exhibit discrepancies with the predictions of the Standard Model, and suggest the presence of new physics in $b\to s$ and $b \to c(u)$ quark level transitions. Motivated by the prospects of the ongoing high-luminosity $B$ factories, we study the exclusive $B \to a_1 (1260) \ell^- \barν_\ell$ process within the Standard Model Effective Field Theory (SMEFT) formalism, to understand the sensitivity of new physics. The new physics parameters are constrained by using the experimental branching fractions of the (semi)leptonic $B \to \ell \barν$ and $B \to (π, ρ, ω) \ell \barν$ processes (where $\ell = e, μ, τ$) which undergo $b \to u \ell \barν$ quark level transitions. We then perform a comprehensive angular analysis of the exclusive $B \to a_1 (1260) \ell^- \barν_\ell$ process in the Standard Model and in the presence of various new physics operators. We also provide the predictions and comment on various observables, such as branching ratio, forward-backward asymmetry, and the test of lepton flavor non universality of the $B \to a_1 (1260) \ell^- \barν_\ell$ channel.

hep-ph↗

arXiv2025

Quantum decoherence signatures in charmless non-leptonic $B$ decays

Quantum coherence plays a crucial role in the dynamics of neutral meson systems, aiding in the extraction of various Standard Model parameters. However, real physical systems always interact with their surroundings, which causes decoherence. In case of time dependent analysis of non-leptonic neutral $B$ meson decays, this decoherence can be modeled using a single parameter, $λ$. Since decoherence can affect the observed dynamics of flavor oscillations and CP violation, it becomes essential to revisit the key SM parameters such as the CKM angles $(α, β, γ)$ and the mass differences of neutral $B$ mesons ($Δm_{d,s}$). In this work, we study the CKM phase $β$ as well as the penguin contributions in the $B_d^0 \to J/ψK_S$ decay mode in the presence of decoherence. We employ the pseudo-experiment (Toy Monte-Carlo) technique and perform an $SU(3)_F$ analysis using the $B_d^0 \to J/ψπ^0$ process. Furthermore, we investigate the $B_d^0 \to π^+ π^-$ decay mode to understand how the decoherence influences the CP violating observables. Our findings reveal that the presence of decoherence can affect crucially the measured values of the observables.

hep-ph↗

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↗

arXiv2025

Exploring the lepton flavor violating decay modes $b \to s μ^{\pm} τ^{\mp}$ in SMEFT approach

We perform an analysis of the consequences of various new physics operators on the lepton flavor violating (LFV) decay modes mediated through $b \to s \ell _1 \ell _2$ transitions. We scrutinize the imprints of the (pseudo)scalar and axial(vector) operators on the exclusive LFV decay channels $ B_{(s)} \rightarrow (ϕ, K^{*}, K_{2}^{*})\ell_{1}\ell_{2}$ and $Λ_{b}\rightarrow Λ\ell_{1}\ell_{2}$, where $\ell_{1}, \ell_{2}$ represent $μ$ or $τ$. The new physics parameters are constrained by using the upper limits of the branching fractions of the $B \to τμ$ and $B \to K τμ$ processes, assuming the new physics couplings to be real. We then explore the key observables such as the branching fraction, the forward-backward asymmetry, and the longitudinal polarisation fraction of the $B \to (K^*, ϕ, K_2^*) τ^{\pm} μ^{\mp}$ decays. In addition, we also investigate the impact of the new physics couplings on the baryonic $Λ_b \to Λτ^{\pm} μ^{\mp}$ decay channels mediated by the $b \to s$ quark level transition. With the experimental prospects at LHCb upgrade and Belle II, we also predict the upper limits of the above-discussed observables, which could intrigue the new physics search in these channels.

hep-ph↗

arXiv2025

Analysis of $b \to c \ell ν$ baryonic decay modes in SMEFT approach

The flavor-changing neutral current decays of heavy bottom quark, alongside the flavor-changing charged current processes mediated by $b \to (c, u)$ in semileptonic $B$ decays are emerged as powerful tools for exploring physics beyond the Standard Model. In this work, we focus on the feasibility of interpreting the processes mediated by $b \to c τν$ transitions, in particular, the semileptonic $b$-baryonic decay modes $Σ_b \to Σ_c^{(*)} τ^-\barν_τ$ and $Ξ_b \to Ξ_c τ^-\barν_τ$ in the context of SMEFT approach. We perform a detailed analysis of the sensitivity of new physics operators on various observables such as branching ratio, forward-backward asymmetry parameter, lepton non-universal observable and the longitudinal polarization fraction of the $b$-baryonic decay channels.

hep-ph↗

arXiv2025

Directional Neutrino Bursts from Spinning and Moving Primordial Black Holes

We show that primordial black holes (PBHs) with significant spin and bulk motion produce sharply collimated neutrino bursts from Hawking evaporation, arising from the interplay of spin-induced angular anisotropy and relativistic Doppler boosting. This effect shifts the neutrino spectrum into the multi-GeV to hundreds of GeV range, where atmospheric backgrounds drop steeply, and enhances the flux by orders of magnitude within a narrow forward cone. We compute the full lab-frame neutrino distribution and derive updated constraints on PBH number density from non-observation of such bursts in IceCube and KM3NeT. Our results identify directional high-energy neutrino bursts as a distinctive, testable signature of spinning PBHs, providing a complementary probe of the PBH dark matter hypothesis and Hawking radiation.

astro-ph.CO↗