arXiv subjects

Sudip Jana

Publications and source records attributed to Sudip Jana.

At least 19 recordsLinked to original sources

arXiv2026

Probe of Solar Neutrino Magnetic Moments through Spin-Flavor Precession: Resonance Structure and Antineutrino Appearance

We investigate solar-neutrino spin--flavor precession (SFP) induced by magnetic moments in the three-active-flavor framework. For Majorana neutrinos, SFP can convert solar neutrinos into antineutrinos of different active flavors. In the Dirac case, SFP instead produces sterile right-handed states and can lead to the disappearance of active neutrinos. Using the full $6\times6$ Hamiltonians and GS98 and AGSS09 solar profiles, we examine propagation-eigenvalue crossings at $B_\perp=0$ and the projected magnetic couplings between the corresponding states. For normal mass ordering and $1\leq E_ν/\mathrm{MeV}\leq20$, we confirm the absence of finite-density Majorana crossings. A magnetically coupled Dirac crossing emerges above approximately $12~\mathrm{MeV}$ but involves only a subdominant electron-flavor component, limiting resonant disappearance. Nonresonant Majorana conversion nevertheless offers a distinctive lepton-number-violating solar $\barν_e$ signal, motivating our sensitivity study for the Jinping Neutrino Experiment. For a proposed $3~\mathrm{kt}$ detector operating for five to ten years, we project a 90\% C.L. sensitivity of $P(ν_e\to\barν_e)\simeq(0.85-1.3)\times10^{-5}$. In the $μ_{12}$-only benchmark, optimistic solar-core transverse magnetic fields of $B_\perp=7-10~\mathrm{MG}$ imply a reach of $|μ_{12}|\simeq(2.3-4.1)\times10^{-13}\,μ_B$, numerically below existing direct-scattering limits and commonly quoted stellar-cooling bounds. This could enable Jinping to provide one of the most stringent projected terrestrial sensitivities to Majorana transition magnetic moments.

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arXiv2026

Probing Neutrinophilic Long-Range Forces at DUNE

Neutrino oscillations provide compelling evidence for physics beyond the Standard Model, while the weakly interacting nature of neutrinos makes them powerful probes of new interactions and hidden sectors. In this work, we investigate a \textit{dark neutrino portal} scenario in which neutrino mass generation is linked to a light dark sector charged under a new $U(1)_D$ gauge symmetry. While Standard Model fields remain neutral under $U(1)_D$, the dark neutrino sector is charged and communicates with the Standard Model exclusively through active--dark neutrino mixing. The associated neutrinophilic mediator induces ultra-long-range interactions, whereby electrons and neutrons in the Earth, Moon, Sun, Milky Way, and the cosmological matter distribution generate sizable matter potentials that modify neutrino oscillations. We explore the sensitivity of the upcoming Deep Underground Neutrino Experiment (DUNE), whose long baseline and pronounced matter effects make it uniquely suited to probe such interactions. We show that DUNE can access previously unexplored regions of parameter space and demonstrate that the same underlying coupling can simultaneously give rise to sizable neutrino self-interactions, including regions relevant for alleviating the Hubble tension, while remaining consistent with current neutrino oscillation constraints.

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arXiv2026

Gravitational Wave Imprints of a High-Quality Axion and the Origin of Flavor Hierarchies

Axions, arising from an anomalous global Peccei-Quinn symmetry $U(1)_{\text{PQ}}$, offer a compelling solution to the strong CP problem but are vulnerable to Planck-suppressed operators. Gauged abelian flavor symmetries $U(1)_F$, invoked to explain the flavor hierarchies via the Froggatt-Nielsen mechanism, can naturally shield the axion from such effects, yielding an accidental high-quality flavored axion with unit domain wall number. Such constructions predict two complementary signatures: (i) flavor-changing neutral currents from $K\toπa$ decays, typically associated with high flavor scales $Λ_{\text{FN}}\gtrsim f_a$, and (ii) stochastic Gravitational Waves (GWs) sourced by the evolution and decay of gauged flavonic and axionic cosmic-string networks. In addition, global axionic strings can efficiently radiate axions, potentially accounting for the observed dark matter relic abundance. We show that the resulting characteristic plateau--valley structure in the GW spectrum provides a distinctive and powerful probe of high-quality flavored axion dark matter models, complementary to low-energy flavor experiments.

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arXiv2025

Flavor Matters, but Matter Flavors: Matter Effects on Flavor Composition of Astrophysical Neutrinos

We show that high-energy astrophysical neutrinos produced in the cores of heavily obscured active galactic nuclei (AGNs) can undergo strong matter effects, thus significantly influencing their source flavor ratios. In particular, matter effects can completely modify the standard interpretation of the flavor ratio measurements in terms of the physical processes occurring in the sources (e.g., $pp$ versus $pγ$, full pion-decay chain versus muon-damped pion decay). We contrast our results with the existing flavor ratio measurements at IceCube, as well as with projections for next-generation neutrino telescopes like IceCube-Gen2. Signatures of these matter effects in neutrino flavor composition would not only bring more evidence for neutrino production in central AGN regions, but would also be a powerful probe of heavily Compton-thick AGNs, which escape conventional observation in $X$-rays and other electromagnetic wavelengths.

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arXiv2025

Signatures of quasi-Dirac neutrinos in diffuse high-energy astrophysical neutrino data

Although the sources of astrophysical neutrinos are still unknown, they are believed to be produced by a population of sources in the distant universe. Measurements of the diffuse, all-sky astrophysical flux can thus be sensitive to flavor and energy-dependent propagation effects, such as very long baseline oscillations. These oscillations are present in certain neutrino mass models, such as when neutrinos are quasi-Dirac. Assuming generic models for the source flux, we find that these oscillations can still be resolved even when integrated over wide distributions in source redshift. We use two sets of IceCube all-sky flux measurements, made with muon and all-flavor neutrino samples, to set constraints at the $3σ$ level on quasi-Dirac mass-splittings between $(5 \times 10^{-19}, 8 \times 10^{-19})~\textrm{eV}^2$. We also consider systematic uncertainties on the source population and find that our results are robust under alternate spectral hypotheses or physical redshift distributions. Our analysis shows that spectral features in the all-sky neutrino measurements provide strong constraints on massive neutrino scenarios and are sensitive to uncharted parameter space.

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arXiv2025

Gravitational Wave Signature and the Nature of Neutrino Masses: Majorana, Dirac, or Pseudo-Dirac?

The fermionic nature of neutrinos and the origin of their tiny masses remain unresolved issues in particle physics, intrinsically connected to lepton number symmetry-conserved for Dirac, violated for Majorana, and effectively pseudo-Dirac when global symmetries invoked for conservation are broken by quantum gravity. We investigate whether distinctive gravitational-wave (GW) signatures can illuminate the nature of neutrino masses and their underlying symmetries, particularly in scenarios where Yukawa couplings are not unnaturally small. To this end, we consider the minimal $B-L$ gauge extension of the Standard Model, where quantum numbers of beyond-SM states determine the neutrino nature and the scale of spontaneous $B-L$ breaking governs mass generation. In this framework, we show that neutrinos yield characteristic GW spectra: Majorana neutrinos with high-scale breaking ($\sim 10^{14}$ GeV) produce local cosmic strings and a flat spectrum across broad frequencies, Dirac neutrinos with low-scale breaking ($\sim 10^{7}$ GeV) generate peaked spectra from first-order phase transitions, and pseudo-Dirac scenarios give kink-like features from domain wall annihilation.

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arXiv2025

Tracing Neutrino Non-Standard Interactions through Charged Lepton Collisions

Neutrino non-standard interactions (NSI) play a crucial role in neutrino oscillations and can provide valuable insights for constructing models of neutrino masses and mixing. While NSI have been widely explored through oscillation and scattering experiments, as well as in cosmological and astrophysical contexts, we focus on probing them at future lepton colliders like the ILC, CLIC, and FCC-$ee$. If NSI arise from heavy mediators above the electroweak scale, these colliders can offer superior sensitivity compared to neutrino experiments across a broad mass range. A notable outcome is that lepton collider data can help resolve parameter degeneracies seen in oscillation studies. We find that large NSI scenarios, proposed to address the tension between T2K and NO$ν$A results, can be completely tested at such collider facilities. We also explore the potential of future colliders like the FCC to probe leptonic NSI using lepton PDFs in proton-proton collisions.

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arXiv2025

How Charged Can Neutrinos Be?

We investigate how neutrinos may acquire small electric charges within the Standard Model framework while preserving electromagnetic gauge invariance. Instead of gauging the standard hypercharge generator $Y$, a linear combination of $Y$ and a new generator $X$ from a gaugable global $U(1)_X$ symmetry is embedded, under which neutrinos transform non-trivially. We demonstrate that minimal scenarios based on flavor-dependent $U(1)_X$ symmetries, such as $X = L_α- L_β$, are incompatible with current neutrino oscillation data. In contrast, we have shown that only flavor-universal $U(1)_X$ symmetries-such as $U(1)_{B-L}$, which shifts both quark and lepton charges, and $U(1)_L$, which modifies only the lepton sector-can generate tiny neutrino charges consistent with observed masses and mixing. We also discuss the necessary connection between such charges and the Dirac nature of neutrinos. By analyzing the phenomenological implications in detail, our findings emphasize that constraints on neutrino charges should be evaluated within the specific framework of the $U(1)_X$ symmetry under consideration, rather than assuming a generic approach, as is often the case.

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arXiv2025

Flavor-Specific Dark Matter Signatures through the Lens of Neutrino Oscillations

We investigate the flavor-specific properties of leptophilic dark matter in neutrino mass models, where dark matter signals are directly correlated with the neutrino oscillation data, providing complementary insights into the neutrino mass hierarchy and CP phases. Notably, this can be accomplished without introducing a flavor-specific portal to dark matter, imposing any new flavor symmetry, or involving flavon fields. As a case study, we analyze the correlation between the flavor-philic nature of dark matter and neutrino oscillation data in the type-II seesaw and Zee-Babu models, and extend this discussion to other neutrino mass models. We analyze the indirect signatures of such leptophilic dark matter, specifically examining the spectrum of the cosmic ray electron/positron flux resulting from the pair annihilation of dark matter in the Galactic halo, and explore correlated lepton-specific signals at collider experiments sensitive to neutrino oscillation data.

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arXiv2024

Radiative Origin of Fermion Mass Hierarchy in Left-Right Symmetric Theory

Despite the remarkable success of the Standard Model, the hierarchy and patterns of fermion masses and mixings remain a profound mystery. To address this, we propose a model employing the rank mechanism, where the originally massless quarks and leptons sequentially get masses. The third-generation masses originate from the seesaw mechanism at the tree level, while those of the second and first generations emerge from one-loop and two-loop radiative corrections, respectively, with a progressive increase in the rank of the mass matrix. This approach does not require new discrete or global symmetries. Unlike other theories of this type that require the introduction of additional scalars, we employ the double seesaw mechanism within a left-right symmetric framework, which allows us to realize this scenario solely through gauge interactions.

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arXiv2024

Restricting Sterile Neutrinos by Neutrinoless Double Beta Decay

The bounds on parameters of the eV and higher scale sterile neutrinos from the $0νββ$ decay have been refined and updated. We present a simple and compact analytic expression for the bound in the $Δm^2_{41} - \sin^2 2θ_{14}$ plane, which includes all relevant parameters. Dependencies of the bound on unknown CP-phases and the type of mass spectrum of light neutrinos (mass ordering and level of degeneracy) are studied in detail. We have computed the bounds using the latest and most stringent data from KamLAND-Zen. The projected constraints from future experiments are estimated. The obtained bounds are confronted with positive indications of the presence of sterile neutrinos as well as with the other existing bounds. The $0νββ$ decay results exclude the regions of parameters implied by BEST and Neutrino-4, and the regions indicated by LSND and MiniBooNE are in conflict with $0νββ$ results combined with $ν_μ-$ disappearance bounds.

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arXiv2024

Neutrinoless Double Beta Decay without Vacuum Majorana Neutrino Mass

We present a proof-of-concept extension to the Standard Model that can generate a non-vanishing neutrinoless double beta decay ($0νββ$) signal without the existence of Majorana neutrinos or lepton number violation in the zero-density vacuum-ground-state Lagrangian. We propose that the $0νββ$ can be induced by the capture of an ultralight scalar field, a potential dark matter candidate, that carries two units of lepton number. This makes the observable $0νββ$ spectrum indistinguishable from the usual $0νββ$ mechanisms by any practical means. We find that a non-zero $0νββ$ rate does not require neutrinos to be fundamentally Majorana particles. However, for sizeable decay rates within the range of next-generation experiments, the neutrino will, generally, acquire an (effective) Majorana mass as the scalar field undergoes a transition to the Bose-Einstein condensate phase. We also discuss the distinction between the aforementioned scenario and the case in which the emission of a lepton-number-two scalar leads to $0νββ$, exhibiting discernible qualitative features that make it experimentally distinguishable from the conventional scenario.

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arXiv2024

Non-Standard Interactions of Supernova Neutrinos and Mass Ordering Ambiguity at DUNE

We show that non-standard neutrino interactions (NSI) can notably modify the pattern of resonant flavor conversion of neutrinos within supernovae and significantly impact the neutronization burst signal in forthcoming experiments such as the Deep Underground Neutrino Experiment (DUNE). The presence of NSI can invert the energy levels of neutrino matter eigenstates and even induce a new resonance in the inner parts close to the proto-neutron star. We demonstrate how DUNE can use these new configurations of energy levels to have sensitivity to NSIs down to $\mathcal{O}(0.1)$. We also elucidate how the effect may result in a puzzling confusion of normal and inverted mass orderings by highlighting the emergence or vanishing of the neutronization peak, which distinguishes between the two mass orderings. Potential implications are analyzed thoroughly.

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arXiv2024

Neutrino masses and mixing from milli-charged dark matter

We propose a simple extension to the Standard Model, wherein neutrinos naturally attain small Majorana masses through a one-loop radiative mechanism featuring particles within the loops characterized by milli-charges. Unlike the conventional scotogenic model, our approach avoids imposing a discrete symmetry or expanding the gauge sector. The minuscule electric charges ensure the stability of the lightest particle within the loop as a viable dark matter candidate. Our investigation systematically scrutinizes the far-reaching phenomenological implications arising from these minuscule charges.

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arXiv2024

Long-lived doubly charged scalars in the left-right symmetric model: catalyzed nuclear fusion and collider implications

We show that the doubly charged scalar from the $SU(2)_R$-triplet Higgs field in the Left-Right Symmetric Model has its mass governed by a hidden symmetry so that its value can be much lower than the $SU(2)_R$ breaking scale. This makes it a long-lived particle while being consistent with all existing theoretical and experimental constraints. Such long-lived doubly charged scalars have the potential to trigger catalyzed fusion processes in light nuclei, which may have important applications for energy production. We show that it could also bear consequences on the excess of large ionization energy loss ($dE/dx$) recently observed in collider experiments.

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arXiv2024

New Resonances of Supernova Neutrinos in Twisting Magnetic Fields

We investigate the effect of resonant spin conversion of the neutrinos induced by the geometrical phase in a twisting magnetic field. We find that the geometrical phase originating from the rotation of the transverse magnetic field along the neutrino trajectory can trigger a new resonant spin conversion of Dirac neutrinos inside the supernova, even if there were no such transitions in the fixed-direction field case. We have shown that even though resonant spin conversion is too weak to affect solar neutrinos, it could have a remarkable consequence on supernova neutronization bursts where very intense magnetic fields are quite likely. We demonstrate how the flavor composition at Earth can be used as a probe to establish the presence of non-negligible magnetic moments, potentially down to $10^{-15}~μ_B$ in upcoming neutrino experiments like the Deep Underground Neutrino Experiment (DUNE), and the Hyper-Kamiokande (HK). Possible implications are analyzed.

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arXiv2023

Muonic Force and Neutrino Non-Standard Interactions at Muon Colliders

The discovery of neutrino oscillations implies that neutrinos are massive and mixed, necessitating an extension of the Standard Model, which may require the introduction of non-standard neutrino interactions (NSI). We investigate the potential of a high-energy muon collider to probe such NSIs with muons, specifically focusing on muonic forces. By analyzing the monophoton signal from the process $μ^+ μ^- \rightarrow ν\overline{ν} γ$, we explore four-fermion contact interactions involving two muons and two neutrinos. Moreover, we examine minimal models that generate scalar and vector-mediated NSIs and study their phenomenology. Projected sensitivities for the strength of NSIs, $ε_{αβ}^{μμ}$, are presented at a 95$\%$ confidence level for a center-of-mass energy of 3 TeV and integrated luminosities of $\mathcal{L} = 1$ and $10~\mathrm{ab}^{-1}$, showcasing the complementarity between a muon collider and other experimental probes.

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arXiv2023

Light Neutrinophilic Dark Matter from a Scotogenic Model

We present a minimal sub-GeV thermal Dark Matter (DM) model where the DM primarily interacts with neutrinos and participates in neutrino mass generation through quantum loop corrections at one-loop level. We discuss the challenges in achieving this in the scotogenic framework and identify a viable variant. Due to minimality and the interplay between obtaining the correct DM relic abundance and neutrino oscillation data, the model predicts (i) a massless lightest neutrino, (ii) enhanced rate of $0νββ$ decay due to loop corrections involving light DM exchange, and (iii) testable lepton flavor-violating signal $μ\to eγ$. Detecting monoenergetic neutrinos from DM annihilation in next-generation neutrino detectors offers a promising way to test this scenario.

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