We review the prospects for probing new physics with neutrino astrophysics. High energy neutrinos provide an important means of accessing physics beyond the electroweak scale. Neutrinos have a number of advantages over conventional astronomy and, in particular, carry information encoded in their flavor degree of freedom which could reveal a variety of exotic neutrino properties. We also outline ways in which neutrino astrophysics can be used to constrain dark matter properties, and explain how neutrino-based limits lead to a strong general bound on the dark matter total annihilation cross-section.
The high-energy astrophysical neutrinos recently discovered by IceCube opened a new way to test Lorentz and CPT violation through the astrophysical neutrino mixing properties. The flavor ratio of astrophysical neutrinos is a very powerful tool to investigate tiny effects caused by Lorentz and CPT violation. There are 3 main findings; (1) current limits on Lorentz and CPT violation in neutrino sector are not tight and they allow for any flavor ratios, (2) however, the observable flavor ratio on the Earth is tied with the flavor ratio at production, this means we can test both the presence of ne…
In this paper, we study the effect of active-neutrino-sterile-neutrino mixing in the expected high-energy astrophysical neutrino flavor content. Non-unitarity in the measurement of the three active neutrinos can be due to the existence of sterile neutrino states. We introduce the concept of the four-flavor tetrahedron in order to visualize the lack of unitarity in the astrophysical neutrino three-flavor triangle. We demonstrate that active-sterile neutrino mixings modify the allowed region of the astrophysical flavor ratio from the standard case. However, a projection of the four-flavor tetrah…
Neutrinoless double beta decay (NDBD) is the only experiment that could probe the Majorana nature of the neutrino. Here we study the theoretical implications of NDBD for models yielding tri-bimaximal lepton mixing like A4 and S4.
In this paper we study the physics potential of the KamLAND detector in probing neutrino oscillation parameters through observation of supernova neutrinos. In particular, we discuss the possibilities of probing the mixing angle $θ_{13}$ and determining the sign of $Δm^2_{32}$ from the total charged current(CC) event rates on the proton and $^{12}{C}$ target, as well as from the CC spectra. We discuss the chances of probing the earth matter effect induced modulations from the observation of CC spectra in the different CC reactions in KamLAND and find the volume required to get a statistically s…
We derive an effective neutrino evolution Hamiltonian and corresponding expression for neutrino spin oscillations probabilities accounting for neutrino interactions with external electric current due to neutrino charge radii and anapole moment. The results are interesting for possible applications in astrophysics.
An impact of a nonzero neutrino millicharge in astrophysics is tested. It is shown that in astrophysical environments electromagnetic interactions of the neutrino millicharge with strong electromagnetic fields as well as weak interactions of the neutrinos with dense background matter can produce new phenomena accessible for astrophysical observations. On this basis a new limit on the neutrino millicharge $q_0<1.3\times10^{-19}e_0$ is obtained. This limit is among the strongest astrophysical constraint on the neutrino millicharge. Some other possible applications of the obtained results to astr…
We derive for the first time an effective neutrino evolution Hamiltonian accounting for neutrino interactions with external magnetic field due to neutrino charge radii and anapole moment. The results are interesting for possible applications in astrophysics.
A short review of form factors, parton distribution functions and generalized parton distributions is given. A possible application of generalized parton distributions in the weak sector is discussed.
The possibility to verify the pseudo-Dirac nature of neutrinos is investigated here via the detection of ultra high energy neutrinos from distant cosmological objects like GRBs. The very long baseline and the energy range from $\sim$ TeV to $\sim$ EeV for such neutrinos invokes the likelihood to probe very small pseude-Dirac splittings. The expected secondary muons from such neutrinos that can be detected by a kilometer scale detector such as ICECUBE is calculated. The pseudo-Dirac nature, if exists, will show a considerable departure from flavour oscillation scenario in the total yield of the…
We review the role of massive neutrinos in astrophysics and cosmology, assuming that the oscillation interpretation of solar and atmospheric neutrinos is correct. In particular, we discuss cosmological mass limits, neutrino flavor oscillations in the early universe, leptogenesis, and neutrinos in core-collapse supernovae.
We review the current status of the neutrino mass and mixing parameters needed to reconstruct the neutrino mass matrix. A comparative study of the precision in the measurement of oscillation parameters expected from the next generation solar, atmospheric, reactor and accelerator based experiments is presented. We discuss the potential of $0νββ$ experiments in determining the neutrino mass hierarchy and the importance of a better $θ_{12}$ measurement for it.
Low energy neutrino processes are ideal probes for new Physics beyond the Standard Model. Cosmological observations and rare nuclear processes can test neutrino mass scales and give definite answers to unsolved basic questions like the Majorana/Dirac nature of the neutrino.
Astrophysical high-energy neutrinos observed by IceCube are sensitive to small effects in a vacuum such as those motivated from quantum gravity theories. Here, we discuss the potential sensitivity of Lorentz violation from the diffuse astrophysical neutrino data in IceCube. The estimated sensitivity reaches the Planck scale physics motivated region, providing IceCube with real discovery potential of Lorentz violation.
The Kamioka-Korea two detector system is a powerful experimental setup for resolving neutrino parameter degeneracies and probing CP violation in neutrino oscillation. In this paper, we study sensitivities of this same setup to several nonstandard neutrino physics such as quantum decoherence, tiny violation of Lorentz symmetry, and nonstandard interactions of neutrinos with matter. In most cases, the Kamioka-Korea two-detector setup is more sensitive than the one-detector setup, except for the Lorentz symmetry violation with CPT violation, and the nonstandard neutrino interactions with matter. …
We investigate the impact of a fourth sterile neutrino at reactor and Spallation Neutron Source neutrino detectors. Specifically, we explore the discovery potential of the TEXONO and COHERENT experiments to subleading sterile neutrino effects through the measurement of the coherent elastic neutrino-nucleus scattering event rate. Our dedicated $χ^2$-sensitivity analysis employs realistic nuclear structure calculations adequate for high purity sub-keV threshold Germanium detectors.
Astrophysical neutrinos are powerful tools to study fundamental properties of particle physics. We perform a general new physics study on ultra high energy neutrino flavor content by introducing effective operators. We find that at the current limits on these operators, new physics terms cause maximal effects on the flavor content, however, the flavor content at Earth is confined to a region related to the initial flavor content.
Motivated by the first observation of coherent-elastic neutrino-nucleus scattering at the COHERENT experiment, we confront the neutrino dipole portal giving rise to the transition of the standard model neutrinos to sterile neutrinos with the recently released CENNS 10 data from the liquid argon as well as the CsI data of the COHERENT experiment. Performing statistical analysis of those data, we show how the transition magnetic moment can be constrained for the range of the sterile neutrino mass between 10 keV and 40 MeV.
We consider a four flavour scenario for the neutrinos where an extra sterile neutrino is introduced with the three families of active neutrinos and study the deviation from three flavour scenario in the ultra high energy (UHE) regime. We calculate the possible muon and shower yields at a 1 Km$^2$ detector such as ICECUBE for these neutrinos from distant UHE sources namely Gamma Ray Bursts (GRBs) etc. Similar estimations for muon and shower yields are also obtained for three flavour case. Comparing the two results we find considerable differences of the yields for these two cases. This can be u…
We discuss the possibility of constraining or discovering the non-standard neutrino physics beyond the standard model with future long baseline neutrino oscillation experiments. Among very many possible experimental set up we discuss neutrino factory and T2KK, in which two detector setting may be useful to achieve the goal. In particular, neutrino factory with two detectors at baselines of 3000 km and 7000 km have a great sensitivity to non-standard interaction (NSI) and solve the $θ_{13}$-NSI confusion problem.
Motivated by a pilot experiment conducted by F.Vannucci et al. during a solar eclipse, we work out the geometry governing the radiative decays of solar neutrinos. Surprisingly, although a smaller proportion of the photons can be detected, the case of strongly non-degenerate neutrinos brings better limits in terms of the fundamental couplings. We advocate satellite-based experiments to improve the sensitivity.
A bilinear R-Parity breaking SUSY model for neutrino mass and mixing predicts the lightest superparticle to decay mainly into a pair of tau leptons or b quarks along with a neutrino for relatively light SUSY spectra. This leads to a distinctive triple bang signature of SUSY events at ultrahigh energy neutrino telescopes like IceCube or Antares. While the expected signal size is only marginal at IceCube, it will be promising for a future multi-km^3 size neutrino telescope.
Sterile neutrino conversion in meter scale baselines can be sensitively probed using monoenergetic, sub-MeV, flavor pure e-neutrinos from an artificial MCi source and the unique technology of LENS designed to oberve the low energy solar neutrino spectrum via tagged CC e-neutrino capture in 115-In. Active-sterile oscillations can be directly observed in the granular LENS detector itself to critically test and extend resuls of short baseline accelerator and reactor experiments.
We examine relation between neutrino oscillation parameters and prediction of lepton flavor violation, in light of deviations from tri-bimaximal mixing. Our study shows that upcoming experimental searches for lepton flavor violation process can provide useful implications for neutrino mass spectrum and mixing angles. With simple structure of heavy right-handed neutrino and supersymmetry breaking sectors, the discovery of tau \to mu gamma decay determines neutrino mass hierarchy if large (order 0.1) reactor angle is established.
We present the reconstruction of neutrino flavor ratios at astrophysical sources. For distinguishing the pion source and the muon-damped source to the 3$σ$ level, the neutrino flux ratios, $R\equivϕ(ν_μ)/(ϕ(ν_e)+ϕ(ν_τ))$ and $S\equivϕ(ν_e)/ϕ(ν_τ)$, need to be measured in accuracies better than 10%.
We propose a new strategy for detecting the CP-violating phases and the effective mass of muon Majorana neutrinos by measuring observables associated with neutrino-antineutrino oscillations in $π^{\pm}$ decays. Within the generic framework of quantum field theory, we compute the non-factorizable probability for producing a pair of same-charged muons in $π^{\pm}$ decays as a distinctive signature of $ν_μ-\bar{ν_μ}$ oscillations. We show that an intense neutrino beam through a long baseline experiment is favored for probing the Majorana phases. Using the neutrino-antineutrino oscillation probabi…
We show the 13 TeV proton-proton collider simulation in a $ν$-two-Higgs-doublet-model ($ν$-THDM). The heavy charged Higgs bosons are produced in pairs through the electroweak processes and decay to the light sterile neutrinos. The light sterile neutrino further decays into a jet-like object with a muon in it. This helps us discriminate the signal from the backgrounds with the standard model jets.
The detection potential of the active neutrino magnetic moment ($ν_{a}$MM) and the active sterile transition magnetic moment ($ν_{s}$MM) of the solar neutrino CE$ν$NS process in future Dark Matter direct detection experiments is studied and compared with the respective allowed range to explain the Xenon1T excess. We find that the sensitivity to the $ν_{a}$MM approaches to the level between $10^{-10}μ_B$ and $10^{-11}μ_B$, which is dominantly limited by the detection threshold. On the other hand, the future solar neutrino CE$ν$NS detection would be powerful in probing the $ν_{s}$MM for the ster…
Can we observe the solar eclipses in the neutrino light? In principle, this is possible by identifying the lunar matter effects on the flavor conversions of solar neutrinos when they traverse the Moon before reaching the detectors at the Earth. Unfortunately, we show that the lunar matter effects on the survival probability of solar $^8{\rm B}$ neutrinos are suppressed by an additional factor of $1.2\%$, compared to the day-night asymmetry. However, we point out that the matter effects on the flavor conversions of high-energy astrophysical neutrinos, when they propagate through the Sun, can be…
The potential for probing extra neutral gauge boson mediators ($Z^\prime$) from low-energy measurements is comprehensively explored. Our study mainly focuses on $Z^\prime$ mediators present in string-inspired $E_6$ models and left-right symmetry. We estimate the sensitivities of coherent-elastic neutrino-nucleus scattering (CE$ν$NS) and neutrino-electron scattering experiments. Our results indicate that such low-energy high-intensity measurements can provide a valuable probe, complementary to high-energy collider searches and electroweak precision measurements.
The simplest unified extension of the Minimal Supersymmetric Standard Model with bilinear R--Parity violation provides a predictive scheme for neutrino masses which can account for the observed atmospheric and solar neutrino parameters. Despite the smallness of neutrino masses R-parity violation is observable at present and future high-energy colliders, providing an unambiguous cross-check of the model.
In the braneworld scenario, gravity and neutrino oscillation can both be used to detect the presence of an extra dimension. We argue that neutrino oscillation is particularly suitable if the size of the extra dimension is small, in which case the signature for the extra dimension is the disappearance of active neutrino fluxes into the bulk, caused by the destructive interference from the Kaluza-Klein states. We discuss a class of models to illustrate this general feature.
We explore the potential of current and next generation of coherent elastic neutrino-nucleus scattering (CE$ν$NS) experiments in probing neutrino electromagnetic interactions. On the basis of a thorough statistical analysis, we determine the sensitivities on each component of the Majorana neutrino transition magnetic moment (TMM), $\left \vert Λ_i \right \vert$, that follow from low-energy neutrino-nucleus experiments. We derive the sensitivity to neutrino TMM from the first CE$ν$NS measurement by the COHERENT experiment, at the Spallation Neutron Source. We also present results for the next p…
Supported by the recent detection of a TXS 0506+056 blazar neutrino with an energy in the TeV-PeV range detected by the IceCube experiment, a probe of a new physics scale LNP related to high-energy cosmic neutrinos is provided. At Standard Model energies, the effect of the underlying physics LNP is first investigated. Then, the recorded IceCube-170922A data is used to approach the scale of such a new physics which lies under the Grand Unified Theory scale 10^25eV.
One of the main neutrino oscillation parameters whose value has not been determined very precisely is the leptonic $δ_{CP}$ phase. Since neutrinos have a tiny but finite mass they can undergo decay both visibly and invisibly. The effect of invisible decay of the third mass eigen state $ν_3$ on the sensitivity to $δ_{CP}$ is analysed here using atmospheric neutrino and anti-neutrino events. Effects of detector resolutions and systematic uncertainties are studied to identify the optimum resolutions and efficiencies required by a detector to obtain a significant sensitivity even in presence of de…
Massive neutrinos can have helicity $s_{\parallel}\neq -1$. Neutrino helicity changes when the neutrino interacts with an external magnetic field and it is possible that the left-handed neutrinos born inside the Sun or a supernova could leave their sources with a different helicity. Since Dirac and Majorana neutrinos have different cross sections in the scattering on electrons for different neutrino helicities, a change in the final neutrino helicity may generate a different number of events and spectra in terrestrial detectors when astrophysical neutrinos have travelled regions with strong ma…
In this article we show the modification in the number of neutrino events ($ν_μ+\barν_μ$) caused by Lorentz Invariant Violation (LIV), $σ=5\times 10^{-24}$ and $10^{-23}$, in neutrino oscillation for a neutrino factory at a distance of 7500 km. The momentum of the muons can vary from 10-50 GeV and we consider $2\times 10^{20}$ decays per year. The modifications in the number of events caused by this $σ$ LIV parameter could be a strong signal of new physics in a future neutrino factory.
We discuss a method to study free protons and neutrons using $ν(\bar ν)$-hydrogen (H) Charged Current (CC) inelastic interactions, together with various precision tests of the isospin (charge) symmetry using $ν$ and $\bar ν$ CC interactions on both H and nuclear targets. Probing free nucleons with (anti)neutrinos provides information about their partonic structure, as well as a crucial input for the modeling of $ν(\barν)$-nucleus (A) interactions. Such measurements can also represent a tool to address some of the limitations of accelerator-based neutrino scattering experiments on nuclear targe…
If massive neutrinos are Majorana particles, then the lepton number should be violated and neutrino-antineutrino oscillations will take place. In this talk, we present the properties of CP violation in neutrino-antineutrino oscillations with a non-unitary leptonic flavor mixing matrix, which naturally arises in the type-I seesaw model due to the mixing between light and heavy Majorana neutrinos. Taking into account current experimental bounds on the leptonic unitarity violation, we show that the CP asymmetries induced by the non-unitary mixing parameters can significantly deviate from those in…
We investigate the effect of CP violation in the leptonic sector. Due to the tiny neutrino masses its value is predicted to be very small and it is far beyond the experimental reach of the current experiments. Recently, the magic baseline experiment from CERN to INO (Indian Neutrino Observatory) with L=7152 km has been proposed to get a sensitive limit on $\sin θ_{13}$. We show that due to such magic baseline neutrino beam it is possible to observe CP violation in the neutrino sector upto several percent for the beam energy between (1-10) GeV.
Low-energy high-resolution neutrino-electron scattering experiments may play an important role in testing the gauge structure of the electroweak interaction. We discuss the use of strong radioactive neutrino sources (e.g. $^{51}$Cr) in underground experiments such as BOREXINO, HELLAZ and LAMA. We display the sensitivity of these detectors in testing the possible existence of extra neutral $E_6$ gauge bosons.
We investigate the feasibility of probing the neutrino mass hierarchy and the mixing angle $ϕ_{13}$ with the neutrino burst from a future supernova. An inverse power-law density $ρ\sim r^{n} $ with varying $n$ is adopted in the analysis as the density profile of a typical core-collapse supernova. The survival probabilities of $ν_{e}$ and $\barν_{e}$ are shown to reduce to two-dimensional functions of $n$ and $ϕ_{13}$. It is found that in the $n-\sin^{2} ϕ_{13}$ parameter space, the 3D plots of the probability functions exhibit highly non-trivial structures that are sensitive to the mass hierar…
We study the possibility of probing different texture zero neutrino mass matrices at long baseline neutrino experiment DUNE. Assuming a diagonal charged lepton basis and Majorana nature of light neutrinos, we first classify the possible light neutrino mass matrices with one and two texture zeros and then numerically evaluate the parameter space in terms of atmospheric mixing angle $θ_{23}$ and Dirac CP phase $δ_{\text{CP}}$ which satisfies the texture zero conditions. We then feed these parameter values into the numerical analysis in order to study the sensitivity of DUNE experiment to them. W…
We analyze the possibility of probing non-standard neutrino interactions (NSI, for short) through the detection of neutrinos produced in a future galactic supernova (SN).We consider the effect of NSI on the neutrino propagation through the SN envelope within a three-neutrino framework, paying special attention to the inclusion of NSI-induced resonant conversions, which may take place in the most deleptonised inner layers. We study the possibility of detecting NSI effects in a Megaton water Cherenkov detector, either through modulation effects in the $\barν_e$ spectrum due to (i) the passage of…
The possible existence of light and heavy sterile neutrinos may give rise to direct and indirect unitarity violation of the $3\times3$ lepton mixing matrix respectively. In the current work we study the potential of future accelerator neutrino facilities in probing the unitarity violation effects. Taking DUNE, T2HK and a low-energy Neutrino Factory (LENF) as working examples of future accelerator neutrino facilities, we study the distinct effects of direct and indirect unitarity violation on the discovery reach of the leptonic CP violation and precision measurements of $θ_{23}$ in the three ne…
We analyze the prospects for testing the cosmic neutrino background and its interpretation as source of Neutrino Dark Energy with the radio telescope LOFAR.
We review some astrophysical and cosmological properties and implications of neutrino masses and mixing angles. These include: constraints based on the relic density of neutrinos, limits on their masses and lifetimes, BBN limits on mass parameters, neutrinos and supernovae, and neutrinos and high energy cosmic rays.
We argue that an effective flavor discrimination in neutrino telescopes is the key to probe the flavor ratios of astrophysical neutrinos at the source and flavor transition mechanisms of these neutrinos during their propagations from the source to the Earth. We first discuss how well one can reconstruct the flavor ratios of astrophysical neutrinos at the source. We then discuss how to probe flavor transition mechanisms of propagating astrophysical neutrinos. In this regard, we propose a model independent parametrization for neutrino flavor transitions, with the neutrino oscillation as a specia…
Neutrinos offer a window to physics beyond the Standard Model. In particular, high-energy astrophysical neutrinos, with TeV-PeV energies, may provide evidence of new, "secret" neutrino-neutrino interactions that are stronger than ordinary weak interactions. During their propagation over cosmological distances, high-energy neutrinos could interact with the cosmic neutrino background via secret interactions, developing characteristic energy-dependent features in their observed energy distribution. For the first time, we look for signatures of secret neutrino interactions in the diffuse flux of h…
One of the important goals for future neutrino telescopes is to identify the flavors of astrophysical neutrinos and therefore determine the flavor ratio. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. We propose a model independent parametrization for describing the above flavor transitions. A few flavor transition models are employed to test our parametrization. The observational test for flavor transition mechanisms through our parametrization …
Quantum decoherence, the evolution of pure states into mixed states, may be a feature of quantum gravity. In this paper, we show how these effects can be modelled for atmospheric neutrinos and illustrate how the standard oscillation picture is modified. We examine how neutrino telescopes, such as ANTARES, are able to place upper bounds on these quantum decoherence effects.
Neutrino masses and the number of light neutrino species can be tested in a variety of laboratory experiments and also can be constrained by particle astrophysics and precision cosmology. A conflict between these various results could be an indication of new physics in the neutrino sector. In this paper we explore the possibility for reconciliation of otherwise discrepant results in a simple model containing a light scalar field which produces Mass Varying Neutrinos (MaVaNs). We extend previous work on MaVaNs to consider issues of neutrino clumping, the effects of additional contributions to n…
Observation of ultra-high energy astrophysical neutrinos and identification of their flavors have been proposed for future neutrino telescopes. The flavor ratio of astrophysical neutrinos observed on the Earth depends on both the initial flavor ratio at the source and flavor transitions taking place during propagations of these neutrinos. The flavor transition mechanisms are well-classified with our model-independent parametrization. We find a new parameter R=ϕ_e/(ϕ_μ + ϕ_τ) can probe directly the flavor transition in the framework of our model-independent parametrization, without the assumpti…
Theories involving extra dimensions, a low (TeV) string scale and bulk singlet neutrinos will produce an effective neutrino magnetic moment which may be large (< 10^{-11} mu_B). The effective magnetic moment increases with neutrino energy, and therefore high energy reactions are most useful for limiting the allowed number of extra dimensions. We examine constraints from both neutrino-electron scattering and also astrophysical environments. We find that supernova energy loss considerations require a number of extra dimensions, n > 1, for an electron neutrino-bulk neutrino Yukawa coupling of ord…
