Oscillation Probability Research Articles

Seesaw, coherence and neutrino oscillations

We present a prescription for consistently constructing non-Fock coherent flavour neutrino states within the framework of the seesaw mechanism, and establish that the physical vacuum of massive neutrinos is a condensate of Standard Model massless neutrino states. The coherent states, involving a finite number of massive states, are derived by constructing their creation operator. This construction fulfills automatically the key requirement of coherence for the oscillations of particles to occur. We comment on the inherent non-unitarity of the oscillation probability induced by the requirement of coherence.

A geometrical look at neutrino oscillation probabilities with non-standard interactions

In this talk, we discuss an alternative description of neutrino flavor oscillations using leptonic unitarity triangles (LUT) which allows for geometric visualization of neutrino oscillations. After a brief review of the LUT description of neutrino oscillations for propagation in vacuum and in matter with standard interactions, we discuss how we can extend this approach to describe neutrino oscillations in presence of new physics. We consider non-standard neutrino interactions (NSI) as the toy model of new physics. The content presented in this talk is based on Ref. [1].

Non-unitary leptonic flavor mixing and CP violation in neutrino-antineutrino oscillations

If massive neutrinos are Majorana particles, then the lepton number should be violated in nature and neutrino-antineutrino oscillations να↔ν‾β (for α,β=e,μ,τ) will definitely take place. In the present paper, we study the properties of CP violation in neutrino-antineutrino oscillations with the non-unitary leptonic flavor mixing matrix, which is actually a natural prediction in the canonical seesaw model due to the mixing between light and heavy Majorana neutrinos. The oscillation probabilities P(να→ν‾β) and P(ν‾α→νβ) are derived, and the CP asymmetries Aαβ≡[P(να→ν‾β)−P(ν‾α→νβ)]/[P(να→ν‾β)+P(ν‾α→νβ)] are also calculated. 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 the limit of a unitary leptonic flavor mixing.

The violation of equivalence principle and four neutrino oscillations for long baseline neutrinos

Violation of equivalence principle predicts that neutrinos of different flavor couple differently with gravity. Such a scenario can give rise to gravity induced flavor oscillations in addition to the usual mass flavor neutrino oscillations during the neutrino propagation. Even if the equivalence principle is indeed violated, their measure will be extremely small. We explore the possibility to probe the violation of equivalence principle (VEP) for the case of long baseline (LBL) neutrinos in a 4-flavor neutrino framework (3 active + 1 sterile) where both mass and gravity induced oscillations are considered. To this end, we have explicitly calculated the oscillation probability in 4-flavor framework that includes in addition to the mass-flavor mixing in matter, the gravity-flavor mixing also. The energy eigenvalues are then obtained by diagonalizing such a 4-flavor mixing matrix. The formalism is then employed to estimate the wrong and right sign muon yields at a far detector for neutrinos produced in a neutrino factory and travel through the Earth matter. These results are compared with the similar estimations when the usual three active neutrinos are considered.

Analysis of the first KM3NeT-ORCA data

ORCA, Oscillation Research with Cosmics in the Abyss, is the low energy KM3NeT neutrino underwater detector, located in the French Mediterranean Sea. It comprises a dense array of optical modules designed to detect Cherenkov light emitted from charged particles resulting from neutrino interactions in the vicinity of the detector. Its main physics goal is the determination of the neutrino mass hierarchy by quantifying the matter-induced effect on the oscillation probabilities of atmospheric neutrinos in the energy range, 3–50 GeV, where the effects of neutrino oscillation phenomena are dominant. In 2019, four detection units were operational. Two more had been added in early 2020. This work presents an overview of the detector performance in the 2019 configuration, as well as its sensitivity to neutrino oscillations.

Understanding Neutrino Oscillations with Particle Accelerator Experiments

Matter-dominant universe cannot be explained with the Standard Model. In order to understand why the current universe mainly consists of matter particles, scientists turned their attention to neutrino oscillations, and conducted research on the properties of the particle and its potential relationship with the matter-antimatter asymmetry observed in the universe. In this research, the probability function of a neutrino oscillation was studied for 2-neutrino case to understand neutrino oscillation in particle accelerator experiments. For a more practical study, the neutrino oscillation probability function was calculated for two neutrino experiments and was used to verify neutrino detector positions and calculated ∆m2 which is mass difference between oscillating two different neutrinos. From this work, it was understood that detectors are located at positions with the highest probability for detecting neutrino oscillations, and it was also confirmed that neutrino were oscillating from muon neutrinos to electron neutrinos in particle accelerator experiments.

Resonance refraction and neutrino oscillations

The refraction index and matter potential depend on neutrino energy and this dependence has a resonance character associated to the production of the mediator in the s−channel. For light mediators and light particles of medium (background) the resonance can be realized at energies accessible to laboratory experiments. We study properties of the energy dependence of the potential for different C-asymmetries of background. Interplay of the background potential and the vacuum term leads to (i) bump in the oscillation probability in the resonance region, (ii) dip related to the MSW resonance in the background, (iii) substantial deviation of the effective ∆m2 above the resonance from the low energy value, etc. We considered generation of mixing in the background. Interactions with background shifts the energy of usual MSW resonance and produces new MSW resonances. Searches of the background effects allow us to put bounds on new interactions of neutrinos and properties of the background. We show that explanation of the MiniBooNE excess, as the bump due to resonance refraction, is excluded.

Sensitivity of a search for eV-scale sterile neutrinos with 8 years of IceCube DeepCore data

Several anomalies in reactor and accelerator neutrino experiments motivate the search for sterile neutrinos with squared mass splittings at the eV-scale. We present an analysis that probes the elements Uμ4 and Uτ4 of the extended (3+1) neutrino mixing matrix using an 8 year data sample from IceCube's DeepCore sub-array containing atmospheric neutrinos between 5 and 300 GeV. We show the expected sensitivities of the analysis to |Uμ4|2 and |Uτ4|2 under the assumption of mass splittings between 1 and 100 eV2, and to |Uμ4|2 for mass splittings below 1 eV2. We specifically discuss how we overcame the challenges of efficiently calculating neutrino oscillation probabilities in the presence of very fast neutrino oscillations involving large Δ m2.

Oscillations Governed by the Incoherent Dynamics in Necroptotic Signaling

Emerging evidences have suggested that oscillation is important for the induction of cell death. However, whether and how oscillation behavior is involved and required for necroptosis remain elusive. To address this question, a minimal necroptotic circuit is proposed based on the CNS pathway. Stochastic parameter analysis demonstrates that the essential structure for oscillation of the CNS circuit is constituted by a paradoxical component embedded with positive feedback among the three protein nodes, i.e., RIP1, caspase-8, and RIP3. Distribution characteristics of all parameters in the CNS circuit with stable oscillation are investigated as well, and a unidirectional bias with fast and slow dynamics that are required for high occurrence probability of oscillation is identified. Four types of oscillation behaviors are classified and their robustness is further explored, implying that the fast oscillation behavior is more robust than the slow behavior. In addition, bifurcation analysis and landscape approach are employed to study stochastic dynamics and global stability of the circuit oscillations, revealing the possible switching strategies among different behaviors. Taken together, our study provides a natural and physical bases for understanding the occurrence of oscillations in the necroptotic network, advancing our knowledge of oscillations in regulating the various cell death signaling.

Violation of equivalence principle in neutrino sector: probing the extended parameter space

The oscillation of neutrino flavors, due to its interferometry nature, is extremely sensitive to the phase differences developing during the propagation of neutrinos. In this paper we investigate the effect of the Violation of Equivalence Principle (VEP) on the flavor oscillation probabilities of atmospheric and cosmic neutrinos observed at neutrino telescopes such as IceCube. Assuming a general parameterization of VEP, dubbed extended parameter space, we show that the synergy between the collected data of high energy atmospheric and cosmic neutrinos severely constrains the VEP parameters. Also, the projected sensitivity of IceCube-Gen2 to VEP parameters is discussed.

Physics prospects with the second oscillation maximum at the Deep Underground Neutrino Experiment

Current long-baseline neutrino-oscillation experiments such as NO$\nu$A and T2K are mainly sensitive to physics in the neighbourhood of the first oscillation maximum of the $\nu_\mu \to \nu_e$ oscillation probability. The future Deep Underground Neutrino Experiment (DUNE) utilizes a wide-band beam tune optimized for CP violation sensitivity that fully covers the region of the first maxima and part of the second. In the present study, we elucidate the role of second oscillation maximum in addressing issues pertaining to unknowns in the standard three flavour paradigm. We consider a new DUNE beam tune optimized for coverage of the region of the second oscillation maxima which could be realized using proposed accelerator upgrades that provide multi-MW of power at proton energies of 8 GeV. We find that addition of the multi-MW 8 GeV beam to DUNE wide-band running leads to modest improvement in sensitivity to CP violation, mass hierarchy, the octant of $\theta_{23}$ as well as the resolution of $\delta$ and the Jarlskog invariant. Significant improvements to the DUNE neutrino energy resolution yield a much larger improvement in performance. We conclude that the standard DUNE wide-band beam when coupled with excellent detector resolution capabilities is sufficient to resolve $\delta$ to better than $\sim 12^\circ$ for all values of $\delta$ in a decade of running. For second maxima (8 GeV 3MW) beam running concurrently with the standard wide-band (80 GeV 2.2 MW) beam for 5 of the 10 years, it is found that $\delta$ can be further resolved better than $\sim 10^\circ$ for all values of $\delta$.

Neutrino propagation in winds around the central engine of sGRB

ABSTRACT Since neutrinos can escape from dense regions without being deflected, they are promising candidates to study the new physics at the sources that produce them. With the increasing development of more sensitive detectors in the coming years, we will infer several intrinsic properties from incident neutrinos. In particular, we centralize our study in those produced by thermal processes in short gamma-ray bursts (sGRBs) and their interactions within the central engine’s anisotropic medium. On the one hand, we consider baryonic winds produced with a strong magnetic contribution, and on the other hand, we treat only neutrino-driven winds. First, we obtain the effective neutrino potential considering both baryonic density profiles around the central engine. Then, we get the three-flavour oscillation probabilities in this medium to finally calculate the expected neutrino ratios. We find a stronger angular dependence on the expected neutrino ratios, which, incidentally, contrast from the expected theoretical ratios without considering the winds’ additional contribution. The joint analysis of this observable, together with the sGRB ejected jet angle, might lead to an effective mechanism to discriminate between the involved merger progenitors (black hole-neutron star (BH-NS) or neutron-star neutron-star(NS-NS)), acting as an additional detection channel to gravitational waves.

Non-standard neutrino oscillations: perspective from unitarity triangles

We formulate an alternative approach based on unitarity triangles to describe neutrino oscillations in presence of non-standard interactions (NSI). Using perturbation theory, we derive the expression for the oscillation probability in case of NSI and cast it in terms of the three independent parameters of the leptonic unitarity triangle (LUT). The form invariance of the probability expression (even in presence of new physics scenario as long as the mixing matrix is unitary) facilitates a neat geometric view of neutrino oscillations in terms of LUT. We examine the regime of validity of perturbative expansions in the NSI case and make comparisons with approximate expressions existing in literature. We uncover some interesting dependencies on NSI terms while studying the evolution of LUT parameters and the Jarlskog invariant. Interestingly, the geometric approach based on LUT allows us to express the oscillation probabilities for a given pair of neutrino flavours in terms of only three (and not four) degrees of freedom which are related to the geometric properties (sides and angles) of the triangle. Moreover, the LUT parameters are invariant under rephasing transformations and independent of the parameterization adopted.

Effect of Sterile Phases on Degeneracy Resolution Capabilities of LBL Experiments

In sterile neutrino (3+1) parameterisation, we observe that sterile phases ($\delta_{14},\delta_{24}$) are always together in oscillation probability, even when the MSW effect is considered. We see that the difference between the sterile phases has a more dominating effect over event rates compared to small variations due to changes in individual values. In this work, we show the value of sterile phase difference ($\delta_{14}-\delta_{24}$) that least affects the parameter degeneracy resolution of $\delta_{13},\theta_{23}$ at long-baseline experiments.

Matter versus vacuum oscillations at long-baseline accelerator neutrino experiments

The neutrino oscillation probabilities at the long-baseline accelerator neutrino experiments are expected to be modified by matter effects. We search for evidence of such modification in the data of T2K and NO[Formula: see text]A, by fitting the data to the hypothesis of (a) matter modified oscillations and (b) vacuum oscillations. We find that vacuum oscillations provide as good a fit to the data as matter modified oscillations. Even extended runs of T2K and NO[Formula: see text]A, with five years in neutrino mode [Formula: see text] and five years in anti-neutrino mode [Formula: see text], cannot make a [Formula: see text] distinction between vacuum and matter modified oscillations. The future experiment DUNE, with neutrino and anti-neutrino runs of five years each [Formula: see text], can rule out vacuum oscillations by itself at [Formula: see text] if the hierarchy is normal. If the hierarchy is inverted, a [Formula: see text] discrimination against vacuum oscillations requires the combination of [Formula: see text] runs of T2K, NO[Formula: see text]A and DUNE.

Neutrino amplitude decomposition in matter

Observation of the interference between the atmospheric-scale and solar-scale oscillations is one of the challenging and tantalizing goals of the ongoing and upcoming neutrino experiments. An inevitable first step required for such analyses is to establish the way the oscillation $S$ matrix can be decomposed into the atmospheric and solar waves, the procedure dubbed as the amplitude decomposition. In this paper, with the use of the perturbative framework proposed by Denton et al. (DMP), we establish the prescription for amplitude decomposition which covers the whole kinematical region of the terrestrial neutrino experiments. We analyze the limits to the atmospheric- and solar-resonance regions to argue that the dynamical two modes of the DMP decomposition can be interpreted as the matter-dressed atmospheric and solar oscillations. The expressions of the oscillation probability, which are decomposed into the noninterference and interference terms, are derived for all the relevant flavor oscillation channels. Through construction of the DMP decomposition, we reveal the nature of $\ensuremath{\psi}$ (${\ensuremath{\theta}}_{12}$ in matter) symmetry as due to the $S$ matrix rephasing invariance. A new picture of the DMP perturbation theory emerged, a unified perturbative framework for neutrino oscillation in earth matter.

Heavy neutrino-antineutrino oscillations in quantum field theory

It has been proposed that the coherent propagation of long-lived heavy neutrino mass eigenstates can lead to an oscillating rate of lepton number conserving (LNC) and violating (LNV) events, as a function of the distance between the production and displaced decay vertices. We discuss this phenomenon, which we refer to as heavy neutrino-antineutrino oscillations, in the framework of quantum field theory (QFT), using the formalism of external wave packets. General formulae for the oscillation probabilities and the number of expected events are derived and the coherence and localisation conditions that have to be satisfied in order for neutrino-antineutrino oscillations to be observable are discussed. The formulae are then applied to a low scale seesaw scenario, which features two nearly mass degenerate heavy neutrinos that can be sufficiently long lived to produce a displaced vertex when their masses are below the W boson mass. The leading and next-to-leading order oscillation formulae for this scenario are derived. For an example parameter point used in previous studies, the kinematics of the considered LNC/LNV processes are simulated, to check that the coherence and localisation conditions are satisfied. Our results show that the phenomenon of heavy neutrino-antineutrino oscillations can indeed occur in low scale seesaw scenarios and that the previously used leading order formulae, derived with a plane wave approach, provide a good approximation for the considered example parameter point.

Dynamics of neuronal oscillations underlying nociceptive response in the mouse primary somatosensory cortex

Pain is caused by tissue injury, inflammatory disease, pathogen invasion, or neuropathy. The perception of pain is attributed to the neuronal activity in the brain. However, the dynamics of neuronal activity underlying pain perception are not fully known. Herein, we examined theta-oscillation dynamics of local field potentials in the primary somatosensory cortex of a mouse model of formalin-induced pain, which usually shows a bimodal behavioral response interposed between pain-free periods. We found that formalin injection exerted a reversible shift in the theta-peak frequency toward a slower frequency. This shift was observed during nociceptive phases but not during the pain-free period and was inversely correlated with instantaneous pain intensity. Furthermore, instantaneous oscillatory analysis indicated that the probability of slow theta oscillations increased during nociceptive phases with an association of augmented slow theta power. Finally, cross-frequency coupling between theta and gamma oscillations indicated that the coupling peak frequency of theta oscillations was also shifted toward slower oscillations without affecting coupling strength or gamma power. Together, these results suggest that the dynamic changes in theta oscillations in the mouse primary somatosensory cortex represent the ongoing status of pain sensation.

ВПЛИВ ЕЛЕКТРОМАГНІТНОГО ВИПРОМІНЮВАННЯ МІЛІМЕТРОВОГО ДІАПАЗОНУ НА ОПТИЧНІ ВЛАСТИВОСТІ ВОДИ В РОЗЧИНАХ ГЕМОГЛОБІНУ

The features of the influence of microwave radiation on the optical properties of pure water and water in solutions of hemoglobin in the near infrared range with the aim to characterize the certain structural and dynamic state of water are investigated. The object of the study was the optical properties of distilled water and aqueous solutions of human hemoglobin in the concentration range of 7 and 15 μm and in the temperature range 10–40°C. The optical spectra were recorded by using a BiospecMini spectrophotometer in the wavelength range of 190–1100 nm. In order to increase the accuracy of the analysis of spectral data the spectra were normalized relative to the baseline which was taken as a line that ran parallel to the horizontal axis due to the minimum value of the optical density in the absorption spectrum. The values of the absorption maxima and the optical density were used as the main parameters of the absorption spectra. The B spline function was used to more accurately determine these parameters. Microwave exposures of distilled water and hemoglobin solutions was performed at a wavelength of 7.1 mm with a maximum 100% output power which was calculated to be approximately 24 mW. The dependence of the parameters of the water absorption spectrum in the range of the second overtone of the OH-valence oscillation of the water molecule on temperature is detailed. There were not found statistically significant changes in the distilled water absorption spectrum in the range of the second overtone OH-valence oscillation of the water molecule after one-hour exposure of the microwave EMR. In hemoglobin solutions in this spectral range there is a small but statistically significant increase in absorption. This may indicate on additional EM-induced activation of the libration motions of water molecules and an increase the probability of deformation oscillations that which are manifested in the near IR range in the band of the second overtone of water.

Prediction of Hydraulic Automatic Transmission Reliability Using Failure Data Based on Exponential Decay Oscillation Distribution Model

Aiming at the problem that the traditional reliability models of mechanical products are used to predict the reliability of hydraulic automatic transmission and the expected result is relatively large, firstly, the empirical distribution model line is used to statistically analyze the failure distribution law of the hydraulic automatic transmission; then, the Fourier transform is used to perform frequency domain analysis on experience distribution; on this basis, comprehensively consider the characteristics of experience distribution and frequency domain characteristics of experience distribution, constructs the reliability model of exponential decay oscillation distribution and the corresponding reliability, failure efficiency and average life calculation model; meanwhile, studies the influence of attenuation coefficient, oscillation amplitude, oscillation angle frequency, and other parameters on the probability distribution characteristics. On this basis, the established probability distribution models are adopted to fit the failure time data of hydraulic automatic gearbox carried by a forklift, and the fitting results are compared with exponential distribution models, three‐parameter Weibull models, and “bathtub curve” models. The comparing results show that the established exponential decayed oscillation distribution model can better describe the probability distribution characteristics of the fault‐free working time of automatic transmission, and the use of this model can obtain a smaller root mean square error. Simultaneously, the research conclusions of this paper can provide meaningful guidance and reference for the analysis of the life distribution model of mechanical products with exponentially attenuated oscillation probability density change law.