Generation Neutrino Research Articles

Earth factories: Creation of the elements from nuclear transmutation in Earth’s lower mantle

Stellar nucleosynthesis is a widely acknowledged theory for the formation of all elements in our universe; traditionally, we say that the highest mass stars transmuted lighter elements into heavier elements lighter than iron. Here, we propose that the formation of 25 elements with smaller atomic numbers than iron resulted from an endothermic nuclear transformation of two nuclei confined in the natural compound lattice core of the Earth’s lower mantle at high temperatures and pressures. This process is accompanied by the generation of neutrinos and is influenced by excited electrons generated by stick-sliding during supercontinent evolution, mantle convection triggered by major asteroid collisions, and nuclear fusion in the Earth’s core. Therefore, our study suggests that the Earth itself has been able to create lighter elements by nuclear transmutation.

Indirect dark matter searches at ultrahigh energy neutrino detectors

High to ultrahigh energy neutrino detectors can uniquely probe the properties of dark matter $\chi$ by searching for the secondary products produced through annihilation and/or decay processes. We evaluate the sensitivities to dark matter thermally averaged annihilation cross section $\langle\sigma v\rangle$ and partial decay width into neutrinos $\Gamma_{\chi\rightarrow\nu\bar{\nu}}$ (in the mass scale $10^7 \leq m_\chi/{\rm GeV} \leq 10^{15}$) for next generation observatories like POEMMA and GRAND. We show that in the range $ 10^7 \leq m_\chi/{\rm GeV} \leq 10^{11}$, space-based Cherenkov detectors like POEMMA have the advantage of full-sky coverage and rapid slewing, enabling an optimized dark matter observation strategy focusing on the Galactic center. We also show that ground-based radio detectors such as GRAND can achieve high sensitivities and high duty cycles in radio quiet areas. We compare the sensitivities of next generation neutrino experiments with existing constraints from IceCube and updated 90\% C.L. upper limits on $\langle\sigma v\rangle$ and $\Gamma_{\chi\rightarrow\nu\bar{\nu}}$ using results from the Pierre Auger Collaboration and ANITA. We show that in the range $ 10^7 \leq m_\chi/{\rm GeV} \leq 10^{11}$ POEMMA and GRAND10k will improve the neutrino sensitivity to particle dark matter by factors of 2 to 10 over existing limits, whereas GRAND200k will improve this sensitivity by two orders of magnitude. In the range $10^{11} \leq m_\chi/{\rm GeV} \leq 10^{15}$, POEMMA's fluorescence observation mode will achieve an unprecedented sensitivity to dark matter properties. Finally, we highlight the importance of the uncertainties related to the dark matter distribution in the Galactic halo, using the latest fit and estimates of the Galactic parameters.

Flavor invariants and renormalization-group equations in the leptonic sector with massive Majorana neutrinos

In the present paper, we carry out a systematic study of the flavor invariants and their renormalization-group equations (RGEs) in the leptonic sector with three generations of charged leptons and massive Majorana neutrinos. First, following the approach of the Hilbert series from the invariant theory, we show that there are 34 basic flavor invariants in the generating set, among which 19 invariants are CP-even and the others are CP-odd. Any flavor invariants can be expressed as the polynomials of those 34 basic invariants in the generating set. Second, we explicitly construct all the basic invariants and derive their RGEs, which form a closed system of differential equations as they should. The numerical solutions to the RGEs of the basic flavor invariants have also been found. Furthermore, we demonstrate how to extract physical observables from the basic invariants. Our study is helpful for understanding the algebraic structure of flavor invariants in the leptonic sector, and also provides a novel way to explore leptonic flavor structures.

GiBUU based neutrino interaction simulations in KM3NeT

The simulation of the neutrino interaction is a crucial step in the simulation chainof a neutrino experiment. The different processes taking part in the neutrino scatteringon a nucleus require several approximations in order to make the simulation possibleand to realize reasonable computation times.This can be realised in different ways, e.g. by parametrised models for the different scattering processes and energy regimes as it is implemented in GENIE.The GiBUU neutrino generator utilises the Boltzmann-Uehling-Uhlenbeck equation tosimulate the particle flow after the neutrino interactions, the so-called final stateinteractions.The detector-specific results in form of the visible energy in the detector afterthe light propagation simulation and the KM3NeT event reconstruction are presented.In addition to that, the comparison to the GENIE based simulation environment in KM3NeT (gSeaGen) is drawn.

Constraining nonstandard neutrino interactions at electron colliders

The presence of nonstandard neutrino interactions (NSI) has a large effect on the precision measurements at next generation neutrino oscillation experiments. Other type of experiments are needed to constrain the NSI parameter space. We study the constraints on NSI with electrons from current and future $e^+e^-$ collider experiments including Belle II, STCF and CEPC. We find that Belle II and STCF will provide competitive and complementary bounds on electron-type NSI parameters compared to the current global analysis, and strong improvements for the constraints on tau-type NSI. In addition, CEPC alone will impose stringent constraints on the parameter space of NSI with electrons. We find that the degeneracy between the left-handed (vector) and right-handed (axial-vector) NSI parameters can be lifted by combining the data from three different running modes, and the allowed ranges for $|\epsilon_{ee}^{eL}|$ ($|\epsilon_{ee}^{eV}|$) and $|\epsilon_{ee}^{eR}|$ ($|\epsilon_{ee}^{eA}|$) can be constrained to be smaller than 0.002 at CEPC even if both of them are present.

Coherent elastic neutrino-nucleus scattering with the νBDX−DRIFT directional detector at next generation neutrino facilities

We discuss various aspects of a neutrino physics program that can be carried out with the neutrino Beam-Dump eXperiment DRIFT ($\nu$BDX-DRIFT) detector using neutrino beams produced in next generation neutrino facilities. $\nu$BDX-DRIFT is a directional low-pressure TPC detector suitable for measurements of coherent elastic neutrino-nucleus scattering (CE$\nu$NS) using a variety of gaseous target materials which include carbon disulfide, carbon tetrafluoride and tetraethyllead, among others. The neutrino physics program includes standard model (SM) measurements and beyond the standard model (BSM) physics searches. Focusing on the Long Baseline Neutrino Facility (LBNF) beamline at Fermilab, we first discuss basic features of the detector and estimate backgrounds, including beam-induced neutron backgrounds. We then quantify the CE$\nu$NS signal in the different target materials and study the sensitivity of $\nu$BDX-DRIFT to measurements of the weak mixing angle and neutron density distributions. We consider as well prospects for new physics searches, in particular sensitivities to effective neutrino non-standard interactions.

New physics at nuSTORM

In this work we investigate the usefulness of nuSTORM as a probe of two new-physics scenarios which are sterile neutrinos and non-unitarity of the neutrino mixing matrix. For the sterile neutrino we show the importance of the neutral current events when combined with the charged current events to constrain the effective mixing angle, $\theta_{\mu \mu}$, and the sterile mixing angles $\theta_{14}$ and $\theta_{24}$. We also study the role nuSTORM will play in the study of neutrino oscillation physics if the three generation neutrino mixing matrix is non-unitary. In this context we elucidate the role of nuSTORM, considering both charged current and neutral current events, in constraining the various non-unitarity parameters such as $\alpha_{11}$, $|\alpha_{21}|$ and $\alpha_{22}$.

Low-Energy Effective Field Theory below the Electroweak Scale: dimension-8 operators

We construct a complete basis of dimension-8 operators in the Low-Energy Effective Field Theory below the Electroweak Scale (LEFT). We find there are 35058 dimension-8 operators in the LEFT for two generations of up-type quarks and three generations of down-type quarks, charged leptons, and left-handed neutrinos. The existence of this operator basis is a necessary prerequisite for matching to the Standard Model Effective Field Theory at the dimension-8 level.

A Solenoid With Partial Yoke for the Dune Near Detector

The Deep Underground Neutrino Experiment (DUNE) at Fermilab is one the most challenging next-generation experiments in the field of neutrino physics. It will feature two detectors for a detailed study of neutrino oscillations using an unprecedentedly intense neutrino beam. The two detectors are a Near Detector located on the Fermilab site, 574 m away from the neutrino generation, and a Far Detector in South Dakota, 1300 km away. The Near Detector consists of three subdetectors, based on different technologies in order to achieve the best understanding of the neutrino beam. One key element of the Near Detector is a High Pressure Argon TPC surrounded by a calorimeter. This detector will need a 0.5 Tesla magnetic field transverse to the neutrino beam direction, with a 7 m diameter, 8 m long warm bore. A thin superconducting solenoid with a partial yoke, needed in order to minimise the amount of material along the path particles take crossing the different elements of the Near Detector is proposed. In this paper we present a detailed magnetic analysis and a preliminary study of the cooling, the cable and the mechanics for this magnet.

CP-Violation in Oscillations of Three Neutrino Generations: the Case of Degenerate Masses

CP-symmetry violates in oscillations of neutrinos in vacuum in presence of three generations. In this case there is an inherent complex phase in PMNS-matrix. When any two neutrino masses degenerate the CP-violation vanishes. In the present article different mechanisms of CP-symmetry recovery are demonstrated in case of two degenerate neutrino mass-states.

SoLid: a short baseline reactor neutrino experiment

The SoLid experiment, short for Search for Oscillations with a Lithium-6 detector, is a new generation neutrino experiment which tries to address the key challenges for high precision reactor neutrino measurements at very short distances from a reactor core and with little or no overburden. The primary goal of the SoLid experiment is to perform a precise measurement of the electron antineutrino energy spectrum and flux and to search for very short distance neutrino oscillations as a probe of eV-scale sterile neutrinos. This paper describes the SoLid detection principle, the mechanical design and the construction of the detector. It then reports on the installation and commissioning on site near the BR2 reactor, Belgium, and finally highlights its performance in terms of detector response and calibration.

Analysing the charged scalar boson contribution to the charged-current B meson anomalies

Experimental measurements collected by the BABAR, Belle, and LHCb experiments on different observables associated with the semileptonic transition , indicate the existence of disagreement respect with the Standard Model predictions. We analyze the charged scalar boson contributions to these charged-current B meson anomalies within the framework of two Higgs doublet model (2HDM) with the most general Yukawa couplings to quarks and leptons from the third generation, involving left-handed and right-handed (sterile) neutrinos. We perform a phenomenological study of the Yukawa couplings parameter space that accommodates these anomalies. We consider the most recent data from HFLAV world-average and Belle combination, and the upper limits and 10%. In addition, we include in our study the prospect measurements on R(D (*)) that the Belle II experiment could achieve and explore, for the first time, the future implications for the corresponding charged scalar Yukawa couplings. This analysis updates the existing literature and includes new important observables. Our results show that current experimental data and Belle II projection favor the interpretation of a charged scalar boson interacting with right-handed neutrinos. Furthermore, as a side analysis regarding the charged scalar boson interpretation, we revisit the relation between R(D*) and by investigating whether the claim that pseudoscalar new physics interpretations of R(D*) are implausible due to the B c lifetime is still valid, to the light of the recent data and Belle II prospects on R(D*). Lastly, we reexamine addressing the R(D (*)) anomalies in the context of the 2HDM of type II. We show that with the current Belle combined data is possible to obtain an available parameter space on the plane for a simultaneous explanation of the anomalies, in consistency with and bounds from inclusive radiative B decays. Moreover, projections at the Belle II experiment suggest that the 2HDM of type II would be no longer disfavored.

Ultrahigh-energy tau neutrino cross sections with GRAND and POEMMA

Next generation neutrino experiments will push the limits in our understanding of astroparticle physics in the neutrino sector to energies orders of magnitude higher than the current state-of-the-art high-energy neutrino experiment, IceCube. These experiments will use neutrinos to tell us about the most extreme environments in the universe, while simultaneously leveraging these extreme environments as probes of neutrino properties at the highest energies accessible in the foreseeable future: $E\sim10^9$ GeV. At these energies neutrinos are readily absorbed in the Earth. Assuming an isotropic distribution, by looking at how the flux varies as a function of angle through the Earth, we show that it is possible to extract the $\nu_\tau$-$N$ cross section with precision at the $\sim20\%$ level ($1\sigma$ assuming Wilks' theorem) given $N_{\rm events}\sim100$ events.

Revealing neutrino nature and CPT violation with decoherence effects

We study decoherence effects on mixing among three generations of neutrinos. We show that in presence of a non-diagonal dissipation matrix, both Dirac and Majorana neutrinos can violate the CPT symmetry and the oscillation formulae depend on the parametrization of the mixing matrix. We reveal the CP violation in the transitions preserving the flavor, for a certain form of the dissipator. In particular, for such dissipators, the CP violation affects all the transitions in the case of Majorana neutrinos, unlike Dirac neutrinos which still preserve the CP symmetry in one of the transitions flavor preserving. The precise form of the dissipation matrix is not known a-priori as it depends on the nature of the phenomenon that originates it. However, our theoretical results show that decoherence effects, if exist for neutrinos, could allow to reveal the neutrino nature and to test fundamental symmetries.

Probing nuclear effects with neutrino-induced charged-current neutral pion production

We study neutrino-induced charged-current (CC) π0 production on carbon nuclei using events with fully imaged final-state proton-π0 systems. Novel use of final-state correlations based on transverse kinematic imbalance enables the first measurements of the struck nucleon’s Fermi motion, of the intranuclear momentum transfer (IMT) dynamics, and of the final-state hadronic momentum configuration in neutrino pion production. Event distributions are presented for (i) the momenta of neutrino-struck neutrons below the Fermi surface, (ii) the direction of missing transverse momentum characterizing the strength of IMT, and (iii) proton-pion momentum imbalance with respect to the lepton scattering plane. The observed Fermi motion and IMT strength are compared to the previous MINERνA measurement of neutrino CC quasielastic-like production. The measured shapes and absolute rates of these distributions, as well as the cross section asymmetries, show tensions with predictions from current neutrino generator models.1 MoreReceived 13 February 2020Accepted 28 September 2020Corrected 11 December 2020DOI:https://doi.org/10.1103/PhysRevD.102.072007Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasNeutrino interactionsNucleus-neutrino interactionsParticle interactionsParticles & Fields

Oscillations of three generations of neutrinos

In this paper, we investigate the evolution of the neutrino flux propagating through dense matter and an intensive magnetic field. As an example, the magnetic field of the coupled sunspots being the sources of solar flares is considered. We assume that neutrinos possess dipole magnetic and anapole moments while the magnetic field is twisting and nonpotential, and its strength may be ≥10 5 Gs. The problem is investigated within three neutrino generations. Possible resonance conversions inside the neutrino flux are studied.

The CP Violating Phase in Matter for Three Generatons of Neutrinos Using the Fritzsch Parametrization

We find an analytical expression of neutrino oscillation in the earth matter medium. We give analytical expresssion for the energy eigenvalue and CP violating phase in matter for three generations of neutrinos using the Fritzsch parametrigation for the flavor mixing matrix.We also study how the earth matter effects can change the CP violating phase. We find that the matter effects is negligibles in normal and inverted neutrino spectrum.We find that CP violating phase is invariant in matter medium.

Signatures of secondary acceleration in neutrino flares

High-energy neutrino flares are interesting prospective counterparts to photon flares since their detection would guarantee the presence of accelerated hadrons within a source, in addition to providing precious information about cosmic-ray acceleration and interactions, thus impacting the subsequent modeling of non-thermal emissions in explosive transients. In these sources, photomeson production can be efficient, producing a large amount of secondary particles, such as charged pions and muons, that decay and produce high-energy neutrinos. Before their decay, secondary particles can experience energy losses and acceleration, which can impact high-energy neutrino spectra and thus affect their detectability. In this work, we focus on the impact of secondary acceleration. We consider a one zone model, characterized mainly by a variability timescaletvar, luminosityLbol, and bulk Lorentz factor Γ. The mean magnetic fieldBis deduced from these parameters. The photon field is modeled by a broken power-law. This generic model allows us to systematically evaluate the maximum energy of high-energy neutrinos in the parameter space of explosive transients and shows that it could be strongly affected by secondary acceleration for a large number of source categories. In order to determine the impact of secondary acceleration on the high-energy neutrino spectrum and, in particular, on its peak energy and flux, we complement these estimates with several case studies. We show that secondary acceleration can increase the maximum neutrino flux and produce a secondary peak at the maximum energy in the case of efficient acceleration. Secondary acceleration could, therefore, enhance the detectability of very-high-energy neutrinos that would be the target of next generation neutrino detectors, such as KM3NeT, IceCube-Gen2, POEMMA, or GRAND.

Heavy dark matter, neutrino masses, and Higgs naturalness from a strongly interacting hidden sector

We consider the extension of the Standard Model (SM) with a strongly interacting QCD-like hidden sector, at least two generations of right-handed neutrinos and one scalar singlet. Once scalar singlet obtains a nonzero vacuum expectation value, active neutrino masses are generated through type-I seesaw mechanism. Simultaneously, the electroweak scale is generated through the radiative corrections involving these massive fermions. This is the essence of the scenario that is known as the "neutrino option" for which the successful masses of right-handed neutrinos are in the range $10^7-10^8$ GeV. The main goal of this work is to scrutinize the potential to accommodate dark matter in such a realization. The dark matter candidates are Nambu-Goldstone bosons which appear due to the dynamical breaking of the hidden chiral symmetry. The mass spectrum studied in this work is such that masses of Nambu-Goldstone bosons and singlet scalar exceed those of right-handed neutrinos. Having the masses of all relevant particles several orders of magnitude above $\mathcal{O}$(TeV), the freeze-out of dark matter is not achievable and hence we turn to alternative scenarios, namely freeze-in. The Nambu-Goldstone bosons can interact with particles that are not in SM but, however, have non-negligible abundance through their not-too-small couplings with SM. Utilizing this, we demonstrate that the dark matter in the model is successfully produced at temperature scale where the right-handed neutrinos are still stable. We note that the lepton number asymmetry sufficient for the generation of observable baryon asymmetry of the Universe can be produced in right-handed neutrino decays. Hence, we infer that the model has the potential to simultaneously address several of the most relevant puzzles in contemporary high-energy physics.

Fractionalized time reversal, parity, and charge conjugation symmetry in a topological superconductor: A possible origin of three generations of neutrinos and mass mixing

The existence of three generations of neutrinos(charged leptons/quarks) and their mass mixing are deep mysteries of our universe. Recently, Majorana's spirit returns in modern condensed matter physics -- in the context of topological Majorana zero modes in certain classes of topological superconductors(TSCs). In this paper, we attempt to investigate the topological nature of the neutrino by assuming that a relativistic Majorana fermion can be divided into four topological Majorana zero modes at cutoff energy scale, e.g. planck scale. We begin with an exactly solvable $1$D lattice model which realizes a $T^2=-1$ time reversal symmetry protected TSC, and show that a pair of topological Majorana zero modes can realize a $T^4=-1$ time reversal symmetry.Moreover, we find that a pair of topological Majorana zero modes can also realize a $P^4=-1$ parity symmetry and even a nontrivial $\overline C^4=-1$ charge conjugation symmetry. Next, we argue that the origin of three generations of neutrinos(charged leptons and quarks) can be naturally explained as three distinguishable ways of forming a pair of complex fermions(with opposite spin polarizations) out of four topological Majorana zero modes, characterized by the $T^4=-1$, $(TP)^4=-1$ and $(T \overline C)^4=-1$ fractionalized symmetries that each complex fermion carries at cutoff energy scale. Finally, we use a semiclassical approach to compute the neutrino mass mixing matrix at leading order(LO), e.g., in the absence of $CP$ violation correction. We obtain $\theta_{12}=31.7^\circ, \theta_{23}=45^\circ$ and $\theta_{13}=0^\circ$(the golden ratio pattern), which is consistent with an $A_5$ flavor symmetry pattern. We further predict an exact mass ratio of the three mass eigenstates of neutrinos with $m_1/m_3=m_2/m_3=3/\sqrt{5}$ and an effective mass of neutrinoless double beta decay $m_{0\nu\beta\beta}=m_1/\sqrt{5}$.