Majorons: A simultaneous solution to the large and small scale dark matter problems

It is shown that the existence of majorons, which enable a heavy neutrino, 500 eV ? m_νH ? 25 keV to decay into a light neutrino m_νL ? 8 eV and a majoron, with lifetime 10⁴ yr ? τ_νH ? 10⁸ yr can solve both the large and small scale dark matter problems. For a primordial “Zeldovich” spectrum of fluctuations the limits are $\text{m}{}_{\mathrm{<mtext>v</mtext><mtext>H</mtext>}}\text{?}\text{?}\text{550}\text{eV and}\text{τ}{}_{\mathrm{<mtext>v</mtext><mtext>H</mtext>}}$ > 10⁷ to 10⁸ yr (the ranges m_νH ? eV and τ_νH ? 10⁸ yr are allowed by the model but galaxy formation becomes problematic). The large scale dark matter problem is how to achieve the critical density as implied by inflation, the small scale problems deal with the halos of galaxies and galaxy formation and perturbation growth. The heavy neutrino could provide the solution to the small scale problem by initiating perturbation growth before decoupling. The decay products will be fast and thus not bound to the initial clumps, thus solving the large scale problem. The low mass relic neutrinos that were not decay products would remain bound in the gravitational potentials which grew from the initial perturbations. The resulting universe would be radiation dominated, which is consistent with present observations if H₀ ? 40 km/s/Mpc. An alternative solution can occur when m_νH ≈ 10 eV: the universe can again become matter dominated in the present epoch. This solution still allows H⁰ ～ 50 km/s/Mpc. The majoron model parameters which best fit the dark matter considerations are presented.     

Constraints on $H_0$ from WMAP and BAO Measurements *

We report the constraints of $H_0$ obtained from Wilkinson Microwave Anisotropy Probe (WMAP) 9-year data combined with the latest baryonic acoustic oscillations (BAO) measurements. We use the BAO measurements from 6dF Galaxy Survey (6dFGS), the SDSS DR7 main galaxies sample (MGS), the BOSS DR12 galaxies, and the eBOSS DR14 quasars. Adding the recent BAO measurements to the cosmic microwave background (CMB) data from WMAP, we constrain cosmological parameters $\Omega_m=0.298\pm0.005$, $H_0=68.36^{+0.53}_{-0.52} {\rm km}\cdot {\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.8170^{+0.0159}_{-0.0175}$ in a spatially flat $\Lambda$ cold dark matter ($\Lambda$CDM) model, and $\Omega_m=0.302\pm0.008$, $H_0=67.63\pm1.30 {\rm km}\cdot{\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.7988^{+0.0345}_{-0.0338}$ in a spatially flat $w$CDM model, respectively. Our measured $H_0$ results prefer a value lower than 70 ${\rm km}\cdot {\rm s}^{-1}\cdot{\rm Mpc}^{-1}$, consistent with the recent data on CMB constraints from Planck (2018), but in $3.1$ and $3.5\sigma$ tension with local measurements of SH0ES (2018) in $\Lambda$CDM and $w$CDM framework, respectively. Our results indicate that there is a systematic tension on the Hubble constant between SH0ES and the combination of CMB and BAO datasets.     

Joint cosmic microwave background and weak lensing analysis: constraints on cosmological parameters

We use cosmic microwave background (CMB) observations together with the red-sequence cluster survey weak lensing results to derive constraints on a range of cosmological parameters. This particular choice of observations is motivated by their robust physical interpretation and complementarity. Our combined analysis, including a weak nucleosynthesis constraint, yields accurate determinations of a number of parameters including the amplitude of fluctuations sigma(8)=0.89+/-0.05 and matter density Omega(m)=0.30+/-0.03. We also find a value for the Hubble parameter of H(0)=70+/-3 km s(-1) Mpc(-1), in good agreement with the Hubble Space Telescope key-project result. We conclude that the combination of CMB and weak lensing data provides some of the most powerful constraints available in cosmology today.     

Uniform Newtonian models with variable mass

A Newtonian version of the spatially homogeneous and isotropic cosmological models with variable mass is presented. Under the assumption that the mass variation is a strict cosmological effect, its influence on the evolution of the scale function is established for the case of a dust-filled universe. Unlike the usual Newtonian models the present value of the deceleration parameter (q 1) obtained from the luminosity distance versus redshift relation can be fitted for a time-decreasing mass. It is also shown that the hyperbolic, parabolic or elliptic character of the fluid motion can be modified along the expansion. Likewise, a Friedmann-type equation with a variable curvature term indicates that in the frame-work of a full geometric variable mass theory, the same may occur with the open, flat or closed character of the universe spatial section.     

Possible observation of electromagnetic cascades in extragalactic space

Arrival directions of gamma-ray-initiated showers with energies over 10¹⁴ eV detected by the Bolivian and Tien Shan high-altitude arrays have been analyzed. Their distribution over the celestial sphere is nonuniform, and in the range of galactic latitudes b⩽30° it is similar to the distribution of Seyfert galaxies, which are at distances ∼1.5–200 Mpc from us, if the Hubble constant is 75 km/s·Mpc. Assuming that Seyfert galaxies are sources of protons with energies higher than 3×10¹⁹ eV, the gamma-rays can be generated in collisions of extragalactic protons with relict photons and in subsequent electromagnetic cascades in the extragalactic space. The upper limit on the extragalactic magnetic field, B≪10⁻⁹ G, is derived. Zh. éksp. Teor. Fiz. 113, 385–397 (February 1998)     

A neutrino-dominated universe

Relic neutrinos produced during the early evolution of the universe will be abundant today (n _v n ) and, if they have a small mass (3 <m _v < 10 eV), may supply the dominant contribution to the total mass density. We review the data on the mass on various scales galaxies, binaries, small groups, large clusters) and conclude that ordinary matter (nucleons) is capable of accounting for the inferred mass on all scales except that of clusters of galaxies. Were the mass in clusters mainly in nucleons, too much helium and too little deuterium would have been produced during primordial nucleosynthesis. Relic neutrinos withm _v > 3 eV are heavy enough to collapse into clusters of galaxies; form _v < 10 eV they are too light to collapse along with binaries and small groups. Such neutrinos would supply the dominant contribution to the mass in the universe.This essay received the first award from the Gravity Research Foundation for the year 1980-Ed.     

Neutrino mass from laboratory: contribution of double beta decay to the neutrino mass matrix

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with ν oscillation experiments. The most sensitive experiment - since eight years the HEIDELBERG-MOSCOW experiment in Gran-Sasso - already now, with the experimental limit of m_ν < 0.26 eV practically excludes degenerate ν mass scenarios allowing neutrinos as hot dark matter in the universe for the smallangle MSW solution of the solar neutrino problem. It probes cosmological models including hot dark matter already now on the level of future satellite experiments MAP and PLANCK. It further probes many topics of beyond SM physics at the TeV scale. Future experiments should give access to the multi-TeV range and complement on many ways the search for new physics at future colliders like LHC and NLC. For neutrino physics some of them (GENIUS) will allow to test almost all neutrino mass scenarios allowed by the present neutrino oscillation experiments.     

Effects of massive neutrinos on the structure formation of the universe

Massive neutrinos affect the structure formation of the universe, characteristically the harmonic pattern of the cosmic microwave background (CMB) radiation and the clustering property of galaxies. Precision observations of the CMB and the power spectrum of galaxy clustering thus lead to the limit on the neutrino mass on the 1 eV scale. I address the principles and the typical results that can be derived from cosmological arguments.     

The dynamical evolution of 3-space in a higher dimensional steady state universe

We investigate a class of cosmological solutions of Einstein’s field equations in higher dimensions with a cosmological constant and an ideal fluid matter distribution as a source. We discuss the dynamical evolution of the universe subject to two constraints that (i) the total volume scale factor of the universe is constant and (ii) the effective energy density is constant. We obtain various interesting new dynamics for the external space that yield a time varying deceleration parameter including oscillating cases when the flat/curved external and curved/flat internal spaces are considered. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the extra dimensions.     

Combined fit of low energy constraints to minimal supersymmetry and discovery potential at LEP II

Within the Constrained Minimal Supersymmetric Standard Model (CMSSM) it is possible to predict the low energy gauge couplings and masses of the 3. generation particles from a few parameters at the GUT scale. In addition the MSSM predicts electroweak symmetry breaking due to large radiative corrections from Yukawa couplings, thus relating theZ ⁰ boson mass to the top quark mass. From ax ² analysis, in which these constraints can be considered simultaneously, one can calculate the probability for each point in the MSGUT parameter space. The recently measured top quark mass prefers two solutions for the mixing angle in the Higgs sector: tanβ in the range between 1 and 3 or alternatively tanβ≈25?50. For both cases we find a uniquex ² minimum in the parameter space. From the corresponding most probable parameters at the GUT scale, the masses of all predicted particles can be calculated at low energies using the RGE, albeit with rather large errors due to the logarithmic nature of the running of the masses and coupling constants. Our fits include full second order corrections for the gauge and Yukawa couplings, low energy threshold effects, contributions of all (s)particles to the Higgs potential and corrections tom _b from gluinos and higgsinos, which exclude (in our notation) positive values of the mixing parameterμ in the Higgs potential for the large tanβ region. Further constraints can be derived from the branching ratio for the radiative (penguin) decay of theb-quark intosγ and the lower limit on the lifetime of the universe, which requires the dark matter density due to the Lightest Super-symmetric Particle (LSP) not to overclose the universe. For the low tanβ solution these additional constraints can be fulfilled simultaneously for quite a large region of the parameter space. In contrast, for the high tanβ solution the correct value for theb→sγ rate is obtained only for small values of the gaugino scale and electroweak symmetry breaking is difficult, unless one assumes the minimal SU(5) to be a subgroup of a larger symmetry group, which is broken between the Planck scale and the unification scale. In this case small splittings in the Yukawa couplings are expected at the unification scale and electroweak symmetry breaking is easily obtained, provided the Yukawa coupling for the top quark is slightly above the one for the bottom quark, as expected e.g. if the larger symmetry group would be SO(10). For particles, which are most likely to have masses in the LEP II energy range, the cross sections are given for the various energy scenarios at LEP II. For low tanβ the production of the lightest Higgs boson, which is expected to have a mass below 103 GeV, is the most promising channel, while for large tanβ the production of charginos and/or neutralinos covers the preferred parameter space.     

Direct determination of the hubble parameter using type IIn supernovae

A novel approach, a Dense Shell Method, is proposed for measuring distances for cosmology. It is based on original Baade idea to relate absolute difference of photospheric radii with photospheric velocity. We demonstrate that this idea works: the new method does not rely on the Cosmic Distance Ladder and gives satisfactory results for the most luminous Type IIn Supernovae. This allows one to make them good primary distance indicators for cosmology. Fixing correction factors for illustration, we obtain with this method the median distance of ≈ 68₋₁₅⁺¹⁹(68%CL) Mpc to SN 2006gy and median Hubble parameter 79₋₁₇⁺²³(68%CL) km/(s Mpc).     

Combined fit of low energy constraints to minimal supersymmetry and discovery potential at LEP II

Within the Constrained Minimal Supersymmetric Standard Model (CMSSM) it is possible to predict the low energy gauge couplings and masses of the 3. generation particles from a few parameters at the GUT scale. In addition the MSSM predicts electroweak symmetry breaking due to large radiative corrections from Yukawa couplings, thus relating theZ ⁰ boson mass to the top quark mass. From ax ² analysis, in which these constraints can be considered simultaneously, one can calculate the probability for each point in the MSGUT parameter space. The recently measured top quark mass prefers two solutions for the mixing angle in the Higgs sector: tan?? in the range between 1 and 3 or alternatively tan????25?50. For both cases we find a uniquex ² minimum in the parameter space. From the corresponding most probable parameters at the GUT scale, the masses of all predicted particles can be calculated at low energies using the RGE, albeit with rather large errors due to the logarithmic nature of the running of the masses and coupling constants. Our fits include full second order corrections for the gauge and Yukawa couplings, low energy threshold effects, contributions of all (s)particles to the Higgs potential and corrections tom _b from gluinos and higgsinos, which exclude (in our notation) positive values of the mixing parameter?? in the Higgs potential for the large tan?? region. Further constraints can be derived from the branching ratio for the radiative (penguin) decay of theb-quark intos?? and the lower limit on the lifetime of the universe, which requires the dark matter density due to the Lightest Super-symmetric Particle (LSP) not to overclose the universe. For the low tan?? solution these additional constraints can be fulfilled simultaneously for quite a large region of the parameter space. In contrast, for the high tan?? solution the correct value for theb??s?? rate is obtained only for small values of the gaugino scale and electroweak symmetry breaking is difficult, unless one assumes the minimal SU(5) to be a subgroup of a larger symmetry group, which is broken between the Planck scale and the unification scale. In this case small splittings in the Yukawa couplings are expected at the unification scale and electroweak symmetry breaking is easily obtained, provided the Yukawa coupling for the top quark is slightly above the one for the bottom quark, as expected e.g. if the larger symmetry group would be SO(10). For particles, which are most likely to have masses in the LEP II energy range, the cross sections are given for the various energy scenarios at LEP II. For low tan?? the production of the lightest Higgs boson, which is expected to have a mass below 103 GeV, is the most promising channel, while for large tan?? the production of charginos and/or neutralinos covers the preferred parameter space.     

General relativity in a (2 + 1)-dimensional space-time

General relativity is formulated for a (2+1)-dimensional space-time. Solutions to the vacuum field equations are locally flat. There are no gravitational waves and no Newtonian attraction between masses. The geometry around a point mass is a cone (locally flat) where the angle deficit at the apex is proportional to the mass. A uniform density planet has a spherical cap interior and a conical exterior solution. A convex polyhedron represents a closed universe with point masses at its vertices and approximates a static spherical universe of uniform density dust.     

Multi-fractal analysis of the galaxy distribution in the Las Campanas redshift survey

We have carried out a multi-fractal analysis of the distribution of galaxies in the three Northern slices of the Las Campanas redshift survey. In this analysis we have studied the scaling properties of the distribution of galaxies on length scales from 20 h⁻¹ Mpc to 200 h⁻¹ Mpc. Our main results are: (1) The distribution of galaxies exhibits a multi-fractal scaling behaviour over the scales 20 h⁻¹ Mpc to 80 h⁻¹ Mpc, and, (2) the distribution is consistent with homogeneity on the scales 80 h⁻¹ Mpc to 200 h⁻¹ Mpc. We conclude that our results are consistent with the Universe being homogeneous at large scales and the transition to homogeneity occurs somewhere in the range 80 h⁻¹ Mpc to 100 h⁻¹ Mpc.     

Physical constants as cosmological constraints

A solution to the primary “missing mass” problem is found in the context of accounting for the coincidence of large dimensionless numbers first noticed by Weyl, Eddington, and Dirac. This solution entails (1) a log₂ relation between the electromagnetic and gravitational coupling constants; (2) setting the maximum radius of curvature at the gravitational radius, 2GM/c ²; (3) a changing gravitational parameterG, which varies as an inverse function of the universal radius of curvature. These features motivate the development of a neo-Friedmann formalism, which employs a function,ε(χ). governing the change from Euclidian to non-Euclidian volumes. Observational consequences include (1) a universal density of 7.6×10^?31g cm^?3, (2) a Hubble parameter of 15 km s^?1 Mpc^?1, (3) an age of the universe of 32×10⁹ yr, (4) a gravitational parameter diminishing at a current rate of 2.2×10^?12 yr^?1, and (5) a deceleration parameter of 1.93. Moreover, it is shown that for a Friedmann-type (λ=0) cosmology (whether open or closed) any deceleration parameter will be represented by a straight line in the (log-log) red shift: luminosity-distance space of the Hubble diagram. The major claim of this paper is that we have devised a model in which the large-scale structure of the universe is completely determined by the values of the fundamental physical constants:c, h, e, andm _e setting the scale, andG selecting the epoch.     

Dark Energy with Phantom Crossing and the H0 Tension

We investigate the possibility of phantom crossing in the dark energy sector and the solution for the Hubble tension between early and late universe observations. We use robust combinations of different cosmological observations, namely the Cosmic Microwave Background (CMB), local measurement of Hubble constant (H0), Baryon Acoustic Oscillation (BAO) and SnIa for this purpose. For a combination of CMB+BAO data that is related to early universe physics, phantom crossing in the dark energy sector was confirmed at a 95% confidence level and we obtained the constraint H0=71.0−3.8+2.9 km/s/Mpc at a 68% confidence level, which is in perfect agreement with the local measurement by Riess et al. We show that constraints from different combinations of data are consistent with each other and all of them are consistent with phantom crossing in the dark energy sector. For the combination of all data considered, we obtained the constraint H0=70.25±0.78 km/s/Mpc at a 68% confidence level and the phantom crossing happening at the scale factor am=0.851−0.031+0.048 at a 68% confidence level.     

Accelerating Flat Universe and Analytic Study of the m-z Relation

An accelerating flat universe with a variable cosmological term is obtained in the Robertson-Walker metric. The variable cosmological term is defined by the correction terms of the metric tensor field. Simple solutions of the scale factor and the cosmological term are shown. In this model of the universe, the magnitude-redshift relation is analytically studied to see if the model reproduces the tendency of the present observational data. The equation of state parameter is touched.     

Holographic DBI-Essence Dark Energy via Power-Law Solution of the Scale Factor

The present work reports a Holographic reconstruction of Dirac–Born–Infeld (DBI)-essence Dark Energy (DE) in a flat FRW universe. The scale factor a(t) is chosen in power law form. We have reconstructed the scalar field and potential and subsequently the equation of state (EoS) parameter ω of the DBI-essence DE. The corresponding plots show increasing scalar field, decaying tension and decaying potential. The reconstructed EoS parameter stays below ?1, showing a phantom-like behavior. The stability of the reconstructed DBI-essence DE is investigated through squared speed of sound $v_{s}^{2}$ : its negative sign reveals that the holographically reconstructed DBI-essence is classically unstable.     

Energy distribution of plasma-assisted electron and ion emission from TGS single crystals

Electron and ion emission accompanying non-thermal plasma processes, produced at the surface of TGS single crystals under driving ac electric field exceeding 10³ V/cm, have been carried out. These plasma-assisted emission of electrons and ions were examined by means of time and energy distribution measurements. The intensity of registered charges (electrons and ions) displayed on the 2 ms time scale are represented by two distinct peaks. Time dependent energy spectrum of charges, detected under our experimental conditions, involves electrons and ions with maximum energy up to 30-40 eV for first peaks and up to 70-80 eV for second one. Additionally, the energy of electrons is focused at about 10-15 eV for first and second peaks and about 60-70 eV for second ones; the ion energy spectrum for both peaks exhibits only distinct low energy maximum focused at about 5-15 eV.     

Early Universe in Scalar-Tensor Theory

We consider the flat Robertson–Walker model in scalar-tensor theory proposed by Lau and Prokhovnik. In this model, the field equations are solved by using “gamma-law” form of equation of state p=(γ−1)ρ, where the adiabatic parameter ‘gamma’ (γ) varies continuously as the universe expands. Our aim is to study how the adiabatic parameter γ should vary so that in the course of its evolution the universe goes through a transition from an inflationary to a radiation-dominated phase. A unified one parameter function of γ has been considered to describe the two early phases of evolution of universe. The solutions show the power-law expansion and cosmological constant is found to be positive and decreasing function of cosmic time. The solutions are compatible with the Dirac’s large number hypothesis. The deceleration parameter has been presented in a unified manner in terms of scale factor, which describes the inflation of the model. The nature of singularity and the physical properties have been discussed in details.