Cosmology with massive neutrinos coupled to dark energy

Cosmological consequences of a coupling between massive neutrinos and dark energy are investigated. In such models, the neutrino mass is a function of a scalar field, which plays the role of dark energy. The evolution of the background and cosmological perturbations are discussed. We find that mass-varying neutrinos can leave a significant imprint on the anisotropies in the cosmic microwave background and even lead to a reduction of power on large angular scales.     

Weighing neutrinos in dynamical dark energy models

正The discovery of neutrino oscillation indicates that neutrinos have masses and each flavor state is actually a superposition of three mass states with masses m_1,m_2,and m_3.However,the neutrino oscillation experiments are not able to measure the absolute masses of neutrinos,but can only measure the squared mass differences between the neutrino mass eigenstates—The solar and reactor experiments gave Δm~2_(21)? 7.5×10~(-5), and the atmospheric and accelerator beam experiments gave|?m~2_(31)|?2.5×10~(-3),which indicates that there are two possible mass orders,i.e.,the normal hierarchy (NH) with m_1m_2?m_3 and the inverted hierarchy(IH) with m_3 ? m_1 m_2.     

Constraints on active and sterile neutrinos in an interacting dark energy cosmology

We investigate the impacts of dark energy on constraining massive(active/sterile) neutrinos in interacting dark energy(IDE)models by using the current observations. We employ two typical IDE models, the interacting w cold dark matter(IwCDM)model and the interacting holographic dark energy(IHDE) model, to make an analysis. To avoid large-scale instability, we use the parameterized post-Friedmann approach to calculate the cosmological perturbations in the IDE models. The cosmological observational data used in this work include the Planck cosmic microwave background(CMB) anisotropies data, the baryon acoustic oscillation data, the type Ia supernovae data, the direct measurement of the Hubble constant, the weak lensing data, the redshift-space distortion data, and the CMB lensing data. We find that the dark energy properties could influence the constraint limits of active neutrino mass and sterile neutrino parameters in the IDE models. We also find that the dark energy properties could influence the constraints on the coupling strength parameter β, and a positive coupling constant, β 0, can be detected at the 2.5σ statistical significance for the IHDE+ν_s model by using the all-data combination. In addition, we also discuss theHubble tension issue in these scenarios. We find that the H_0 tension can be effectively relieved by considering massive sterile neutrinos, and in particular in the IHDE+νsmodel the H_0 tension can be reduced to be at the 1.28σ level.     

Effects of dark energy interacting with massive neutrinos and dark matter on universe evolution

In this paper we investigate the evolution of the cosmology model with dark energy interacting with massive neutrinos and dark matter. Using the numerical method to investigate the dynamical system, we find that the stronger the interaction between dark energy and dark matter, the lower the ratio of dark matter in the universe is; also, the stronger the interaction between dark energy and massive neutrinos, the lower the ratio of massive neutrinos in the universe is. On the other hand, the interaction between dark energy and dark matter or massive neutrinos has an effect on disturbing the universe's acceleration; we also find that our universe is still accelerating.     

Sterile neutrinos, dark matter, and pulsar velocities in models with a Higgs singlet

We identify the range of parameters for which the sterile neutrinos can simultaneously explain the cosmological dark matter and the observed velocities of pulsars. To satisfy all cosmological bounds, the relic sterile neutrinos must be produced sufficiently cold. This is possible in a class of models with a gauge-singlet Higgs boson coupled to the neutrinos. Sterile dark matter can be detected by the x-ray telescopes. The presence of the singlet in the Higgs sector can be tested at the CERN Large Hadron Collider.     

Confronting cosmic ray electron and positron excesses with hybrid triplet Higgs portal dark matter

We perform a detailed study of scalar dark matter with triplet Higgs extensions of the Standard Model in order to explain the cosmic ray electron and positron excesses reported by AMS-02 and DAMPE. A detailed analysis of the AMS-02 positron excess reveals that for different orderings (normal, inverted, and quasi-degenerate) of neutrino mass, the hybrid triplet Higgs portal framework is more favored with respect to the single triplet Higgs portal for TeV scale dark matter. We also show that the resonant peak and continuous excess in DAMPE cosmic ray data can be well explained with the hybrid triplet Higgs portal dark matter when a dark matter sub-halo nearby is taken into account.     

Searching for sterile neutrinos in dynamical dark energy cosmologies

We investigate how the dark energy properties change the cosmological limits on sterile neutrino parameters by using recent cosmological observations. We consider the simplest dynamical dark energy models, the wCDM model and the holographic dark energy(HDE) model, to make an analysis. The cosmological observations used in this work include the Planck 2015 CMB temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova data, the Hubble constant direct measurement data, and the Planck CMB lensing data. We find that, m_(ν,sterile)~(eff) 0.2675 eV and N_(eff) 3.5718 for ΛCDM cosmology, m_(ν,sterile)~(eff) 0.5313 eV and N_(eff) 3.5008 for wCDM cosmology, and m_(ν,sterile)~(eff) 0.1989 eV and N_(eff) 3.6701 for HDE cosmology, from the constraints of the combination of these data. Thus, without the addition of measurements of growth of structure, only upper limits on both m_(ν,sterile)~(eff) and N_(eff) can be derived, indicating that no evidence of the existence of a sterile neutrino species with e V-scale mass is found in this analysis. Moreover, compared to the ΛCDM model, in the wCDM model the limit on m_(ν,sterile)~(eff) becomes much looser, but in the HDE model the limit becomes much tighter. Therefore, the dark energy properties could significantly influence the constraint limits of sterile neutrino parameters.     

Dark energy interacting with neutrinos and dark matter: a phenomenological theory

A model for a flat homogeneous and isotropic Universe composed of dark energy, dark matter, neutrinos, radiation and baryons is analyzed. The fields of dark matter and neutrinos are supposed to interact with the dark energy. The dark energy is considered to obey either the van der Waals or the Chaplygin equations of state. The ratio between the pressure and the energy density of the neutrinos varies with the red-shift simulating massive and non-relativistic neutrinos at small red-shifts and non-massive relativistic neutrinos at high red-shifts. The model can reproduce the expected red-shift behaviors of the deceleration parameter and of the density parameters of each constituent. Dedicated to Professor Ingo Müller on the occasion of his seventieth birthday.     

Solar neutrinos in models involving an extended Higgs sector

Neutrino oscillations in matter and in a magnetic field are investigated within models involving an extended Higgs sector. The left-right model containing a bidoublet and two triplets of Higgs fields (LRM) and the general two-Higgs-doublet model (GTHDM) are chosen by way of example. It is shown that the interaction of leptons with physical Higgs bosons can substantially change the pattern of oscillations in these models in relation to the predictions of the Standard Model (SM). Upper limits on the Yukawa coupling constants and on the Higgs boson masses are found in order to obtain maximum corrections to the SM solar-matter potential V ^SM. By using constraints on these parameters from the literature and those that are obtained here, it is possible to estimate corrections to V ^SM that come exclusively from charged Higgs bosons. The maximum value of these corrections is 40% of V ^SM within the LRM and 10% of V ^SM within the GTHDM. The entire body of information about the contributions of physical Higgs bosons to the solar-matter potential can be obtained by studying the Lorentz structure of the amplitudes for the reactions e ^? ν _l → e ^? ν _l′ at low energies.     

A 4-neutrino model with a Higgs triplet

We take as a starting point the Gelmini–Roncadelli model enlarged by a term with explicit lepton number violation in the Higgs potential and add a neutrino singlet field that is coupled via a scalar doublet to the usual leptons. This scenario allows us to take into account all three present indications in favor of neutrino oscillations provided by the solar, atmospheric, and LSND neutrino oscillation experiments. Furthermore, it suggests a model which reproduces naturally one of the two 4-neutrino mass spectra favored by the data. In this model, the solar neutrino problem is solved by large mixing MSW transitions, and the atmospheric neutrino problem by transitions of into a sterile neutrino. Received: 11 May 1999 / Published online: 3 February 2000     

Exploring the hyperchargeless Higgs triplet model up to the Planck scale

We examine an extension of the SM Higgs sector by a Higgs triplet taking into consideration the discovery of a Higgs-like particle at the LHC with mass around 125 GeV. We evaluate the bounds on the scalar potential through the unitarity of the scattering matrix. Considering the cases with and without \(\mathbb {Z}_2\)-symmetry of the extra triplet, we derive constraints on the parameter space. We identify the region of the parameter space that corresponds to the stability and metastability of the electroweak vacuum. We also show that at large field values the scalar potential of this model is suitable to explain inflation.     

Physics with low energy neutrons and neutrinos

Recent years have seen significant progress in the development of neutron polarizers and polarization analysis, due, in particular, to the work done by the Mainz group. A number of new experiments with polarized neutrons will be discussed, both from the fields of neutron particle physics and of magnetism. Further recent work on neutrino mass measurements will be reviewed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Astroparticle physics with high energy neutrinos: from AMANDA to IceCube

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature produces protons and photons with energies in excess of 10²⁰ eV and 10¹³ eV, respectively. The puzzle of where and how Nature accelerates the highest energy cosmic particles is unresolved almost a century after their discovery. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the science reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos. The outline of this review is as follows:

Introduction

Why kilometer-scale detectors?

Cosmic neutrinos associated with the highest energy cosmic rays

High energy neutrino telescopes: methodologies of neutrino detection

High energy neutrino telescopes: status

     

Detection of low energy solar neutrinos with HPGermanium

The potential of the GENIUS proposal [1] to measure the spectrum of low energy solar neutrinos in real time is studied. The detection reaction is elastic neutrino-electron scattering 9 + e M 9 + e. The energy resolution for detecting the recoil electrons is about 0.3%, the energy threshold is a few keV. The expected number of events for a target of one ton of natural germanium is 3.6 events/day for pp-neutrinos and 1.3 events/day for ⁷Be-neutrinos, calculated in the standard solar model (BP98 [2]). It should be feasible to achieve a background low enough to measure the low energy solar neutrino spectrum.     

Search for cold dark matter and solar neutrinos with GENIUS and GENIUS-TF

The new project GENIUS will cover a wide range of the parameter space of predictions of supersymmetry for neutralinos as cold dark matter. Further, it has the potential to be a real-time detector for low-energy (pp and ⁷Be) solar neutrinos. The GENIUS Test Facility has just been funded and will come into operation by the end of 2001.     

Star models with dark energy

We have constructed star models consisting of four parts: (i) a homogeneous inner core with anisotropic pressure (ii) an infinitesimal thin shell separating the core and the envelope; (iii) an envelope of inhomogeneous density and isotropic pressure; (iv) an infinitesimal thin shell matching the envelope boundary and the exterior Schwarzschild spacetime. We have analyzed all the energy conditions for the core, envelope and the two thin shells. We have found that, in order to have static solutions, at least one of the regions must be constituted by dark energy. The results show that there is no physical reason to have a superior limit for the mass of these objects but for the ratio of mass and radius.