The latest data of the two long-baseline accelerator experiments NO$\nu$A and T2K, interpreted in the standard 3-flavor scenario, display a tension. A mismatch in the determination of the standard CP-phase $\delta_{\mathrm {CP}}$ extracted by the two experiments is evident in the normal neutrino mass ordering. While NO$\nu$A prefers values close to $\delta_{\mathrm {CP}} \sim 0.8 \pi$, T2K...
We study the phenomenology of the minimal (2,2) inverse-seesaw model supplemented with Abelian flavour symmetries. To ensure maximal predictability, we establish the most restrictive flavour patterns which can be realised by those symmetries. This setup requires adding an extra scalar doublet and two complex scalar singlets to the Standard Model, paving the way to implement spontaneous CP...
The phenomenon of Neutrino Oscillation has been very well confirmed by a plethora of data; we are now entering a precision era in which the mixing angles and mass differences are going to be measured with unprecedented precision by ongoing and planned experiments. However, the new measurements could reveal that the standard three flavor scenario is not enough for a complete description of...
Ultra High Energy neutrinos may represent a unique opportunity
to unveil possible new physics interactions in the neutrino sector. At
this regard, we have investigated the effects on high and ultrahigh energy
active neutrino fluxes due to active-sterile secret interactions mediated
by a new pseudoscalar particle. These interactions become relevant at
very different energy scales...
Neutrino oscillations occur due to non-zero masses and they are believed to maintain quantum coherence even over astrophysical length scales.It is thus natural to explore geometric aspects of the phases involved as well as think about quantification of the coherence properties of neutrinos via temporal correlations in the form of Leggett-Garg Inequalities (LGI). In this paper, we study the...
We calculate the rates of radiative $\beta^- \to \alpha^- + \gamma$ decays for $(\alpha, \beta) = (e, \mu)$, $(e, \tau)$ and $(\mu, \tau)$ by taking the {\it unitary} gauge in the $(3+n)$ active-sterile neutrino mixing scheme, and make it clear that constraints on the unitarity of the $3\times 3$ Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrix $U$ extracted from $\beta^- \to \alpha^- + \gamma$...
Neutrino non-standard interactions (NSIs) have been actively investigated both theoretically and experimentally in the past. Yet null signals of any new physics at colliders and from low-energy precision measurements have gradually motivated the investigation of new physics model-independently. Effective Field Theories (EFTs) provide such a systematic and model-independent framework. In this...
In this talk, I will explore a surprising connection between speculative issues in elementary particle physics and the Sun. I will show how the extreme sensitivity of nuclear reaction Coulomb barrier penetration at the low energies of the solar core and the recent observation of the CNO neutrinos from the Sun by the Borexino collaboration could be leveraged to probe aspects of the non-standard...
Neutrino electromagnetic properties are import windows in neutrino physics to go beyond the Standard Model. The coherent elastic neutrino-nucleus scattering process is a powerful probe of the neutrino electromagnetic properties, which was first observed in 2017 at the COHERENT experiment by the cesium-iodide (CsI) detector and later in 2020 at the argon (Ar) detector.
In this talk, we present...
In this talk, I summarize the investigation revolving around neutrino physics within the framework of extended theories of gravity. By relying on the covariant reformulation of Pontecorvo’s formalism, one can evaluate the oscillation probability of neutrinos propagating in static spacetimes described by gravitational actions quadratic in the curvature invariants. In particular, it is shown...
The observation of coherent elastic neutrino-nucleus scattering performed by the COHERENT experiment with cesium iodide in 2017 and with liquid argon in 2020, represents an innovative and powerful tool for investigating non-standard interactions not included in the Standard Model and interactions mediated by yet to be discovered light neutral vector bosons.
We present new constraints on three...
We study the connection between the two indications of physics beyond the Standard Model (SM): the masses and mixing of neutrinos and the existence of dark matter (DM). The most attractive proposal for the origin of neutrino mass, the type I seesaw mechanism, can also account for matter-antimatter asymmetry via leptogenesis. We show that a minimal extension of type I seesaw models can also...
I will discuss our recent work on a simple scoto-seesaw model that accounts for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal $\mathcal{Z}_8$ discrete symmetry, broken to a residual $\mathcal{Z}_2$ subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet,...
Determining the leptonic CP-violation is one of the main objectives of the neutrino oscillation experiments. Long-baseline (LBL) experiments are expected to play a crucial role in this direction. Two LBL experiments T2K and NO$\nu$A are already playing a leading role in addressing this issue. Apart from this, a few highly sophisticated LBL experiments like DUNE, T2HK, and ESS have also been...
In the constrained sequential dominance (CSD), tri-bimaximal mixing (TBM) pattern of the neutrino sector has been explained, by proposing a certain Yukawa coupling structure for the right-handed neutrinos of the model. However, from the current experimental data it is known that the values of the neutrino mixing angles are deviated from the TBM values. In order to explain this neutrino mixing,...
We present a simple model on neutrino masses and mixings based on $S_4$ modular symmetry. Two right-handed neutrinos and three fermion singlets are introduced to account for the light neutrino masses through inverse seesaw and to provide an intermediate scale sterile neutrino as a dark matter candidate. The model has a viable parameter space given the latest constraints on lepton mixing matrix...
The ANITA experiment has registered two anomalous events that can be interpreted as $\nu_\tau$ or $\bar{\nu}_\tau$ with a very high energy of O(0.6)~EeV emerging from deep inside the Earth. At such high energies, the Earth is opaque to neutrinos so the emergence of these neutrinos at such large zenith angles is a mystery. I will present a model that explains the two anomalous events through a...
The constraints on invisible neutrino decay can come from future planned/proposed long baseline experiments - T2HK/T2HKK and ESS$\nu$SB. The T2HKK and ESS$\nu$SB experiments are both designed to have energy peak near the second-oscillation maximum of $P_{\mu e}$ while T2HK has the energy peak at the first oscillation maximum of $P_{\mu e}$. We perform a full three flavour study using matter...
We use perturbation theory to obtain neutrino oscillation probabilities, including the standard mass-mixing paradigm and non-standard neutrino interactions (NSI). The perturbation is made on the standard parameters ${\Delta}{m}_{21}^{2}/{\Delta}{m}_{31}^{2}$ and sin2(θ13) and on the non-diagonal NSI parameters, but keeps diagonal NSI parameters non-perturbated. We perform the calculation for...
The evolution of effective neutrino masses and mixing parameters in the ordinary matter can be characterized by a complete set of differential equations with respect to the matter parameter $a \equiv 2\sqrt{2}G^{}_{\rm F}N^{}_eE$, in analogy with the renormalization-group equations (RGEs) for running parameters. With some reasonable approximations, we find analytical solutions to the above...
In this work, we investigate the effects of non-unitary neutrino mixing on the determination of current unknown parameters in neutrino oscillation physics. From our analysis, we found that non-unitarity parameters in the 21 sector are sensitive to the NOνA experiment. However, it is observed that the NOνA experiment is not expected to improve the current knowledge of those parameters. We also...
Two and three flavor oscillating neutrinos are shown to exhibit the properties bipartite and tripartite quantum entanglement [1]. Neutrino eigenstates are mapped to qubits used in quantum information theory. Such quantum bits of the neutrino state can be encoded on a IBMQ computer using quantum computing as a tool. We show the implementation of entanglement in the two neutrino system (in...
We explore the role of matter effect in the evolution of neutrino oscillation parameters in the presence of non-standard interactions (NSIs). We derive approximate analytical expressions showing evolution of mass-mixing parameters in matter and in presence of NSIs. We observe that only the NSIs in (2,3) block ($\varepsilon_{\mu\mu}$, $\varepsilon_{\tau\tau}$, and $\varepsilon_{\mu\tau}$)...
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 $\varepsilon_{\mu\tau}$, which has the maximum impact on the muon survival probability...
We introduce a renormalizable and anomaly-free $U(1)^\prime$ gauge extension of the standard model, and show that it can provide a consistent explanation of a number of prominent low energy anomalies. We show that the simultaneous presence of all portal connections between a neutral dark sector and the SM lead to unique phenomenological signatures at experiment. We further discuss these...
The neutrino experiments that in the near future are expected to shed some light on a series of open fundamental questions (like the final proof of the leptonic CP violation and the determination of its value, the \theta_23 octant determination, the solution of the mass ordering problem) will also reinforce our knowledge of the general neutrino properties and they could be used to search for...
