15370571
Gravitons as super-strong interacting particles, and low-energy quantum gravity
It is shown by the author that if gravitons are super-strong interacting particles and the low-temperature graviton background exists, the basic cosmological conjecture about the Dopplerian nature of redshifts may be false. In this case, a full magnitude of cosmological redshift would be caused by interactions of photons with gravitons. A new dimensional constant which characterizes one act of interaction is introduced and estimated. Non-forehead collisions with gravitons will lead to a very specific additional relaxation of any photonic flux. It gives a possibility of another interpretation of supernovae 1a data - without any kinematics. Of course, all of these facts may implicate a necessity to change the standard cosmological paradigm. Some features of a new paradigm are discussed here, too. A quantum mechanism of classical gravity based on an existence of this sea of gravitons is described for the Newtonian limit. This mechanism needs graviton pairing and "an atomic structure" of matter for working it, and leads to the time asymmetry. If the considered quantum mechanism of classical gravity is realized in the nature, than an existence of black holes contradicts to Einstein's equivalence principle. It is shown that in this approach the two fundamental constants - Hubble's and Newton's ones - should be connected between themselves. The theoretical value of the Hubble constant is computed. In this approach, every massive body would be decelerated due to collisions with gravitons that may be connected with the Pioneer 10 anomaly. It is shown that the predicted and observed values of deceleration are in good agreement. Some unsolved problems are discussed, so as possibilities to verify some conjectures in laser-based experiments.
14410547
Model of graviton-dusty universe
Primary features of a new cosmological model, which is based on conjectures about an existence of the graviton background and superstrong gravitational quantum interaction, are considered. An expansion of the universe is impossible in such the model because of deceleration of massive objects by the graviton background, which is similar to the one for the NASA deep space probes Pioneer 10, 11. Redshifts of remote objects are caused in the model by interaction of photons with the graviton background, and the Hubble constant depends on an intensity of interaction and an equivalent temperature of the graviton background. Virtual massive gravitons would be dark matter particles. They transfer energy, lost by luminous matter radiation, which in a final stage may be collected with black holes and other massive objects.
18867033
A quantum gravitational model of redshifts
The main features of an alternative model of redshifts are described here. The model is based on conjectures about an existence of the graviton background with the Planckian spectrum and a super-strong character of quantum gravitational interaction. This model is connected with the assumed quantum mechanism of gravity. A behavior of two theoretical functions of a redshift $z$ in this model - the geometrical distance $r(z)$ and the luminosity distance $D_{L}(z)$ - and an existence of two different cosmological horizons for any observer are discussed.
16422963
May gravitons be super-strong interacting particles?
A scheme, in which gravitons are super-strong interacting, is described. The graviton background with the Planckian spectrum and a small effective temperature is considered as a reservoir of gravitons. A cross-section of interaction of a graviton with any particle is assumed to be a bilinear function of its energies. Any pair of bodies are attracting not due to an exchange with its own gravitons, but due to a pressure of external gravitons of this background. A graviton pairing is necessary to obtain classical gravity. Any divergencies are not possible in such the model because of natural smooth cut-offs of the graviton spectrum from both sides. Some cosmological consequences of this scheme are discussed, too. Also it is shown here that the main conjecture of this approach may be verified at present on the Earth.
16705419
A Fine quantum mechanism of classical gravity
It is shown that screening the background of super-strong interacting gravitons ensures the Newtonian attraction, if a part of single gravitons is pairing and graviton pairs are destructed by collisions with a body. If the considered quantum mechanism of classical gravity is realized in the nature, than an existence of black holes contradicts to the equivalence principle. In such the model, Newton's constant is proportional to $H^{2}/T^{4},$ where $H$ is the Hubble constant, $T$ is an equivalent temperature of the graviton background. The estimate of the Hubble constant is obtained for the Newtonian limit: $H=3.026 \cdot 10^{-18} s^{-1}$ (or $94.576 km \cdot s^{-1} \cdot Mpc^{-1}$).
16526170
Small effects of low-energy quantum gravity
Small effects of quantum gravity on the scale $\sim 10^{-3} eV$ and their cosmological consequences are discussed and compared with observations of supernovae 1a, gamma-ray bursts and galaxies.
9519755
The semileptonic form factors of B and D mesons in the Quark Confinement Model
Abstract: The form factors of the weak currents, which appear in the semileptonic decays of the heavy pseudoscalar mesons are calculated within the quark confinement model by taking into account, for the first time, the structure of heavy-meson vertex and the finite quark mass contribution in the heavy-quark propagators. The results are in quite good agreement with the experimental data.
118722197
Testing Lorentz invariance of dark matter
We study the possibility to constrain deviations from Lorentz invariance in dark matter (DM) with cosmological observations. Breaking of Lorentz invariance generically introduces new light gravitational degrees of freedom, which we represent through a dynamical timelike vector field. If DM does not obey Lorentz invariance, it couples to this vector field. We find that this coupling affects the inertial mass of small DM halos which no longer satisfy the equivalence principle. For large enough lumps of DM we identify a (chameleon) mechanism that restores the inertial mass to its standard value. As a consequence, the dynamics of gravitational clustering are modified. Two prominent effects are a scale dependent enhancement in the growth of large scale structure and a scale dependent bias between DM and baryon density perturbations. The comparison with the measured linear matter power spectrum in principle allows to bound the departure from Lorentz invariance of DM at the per cent level.
118410366
Radiative decays of double heavy baryons in a relativistic constituent three-quark model including hyperfine mixing effects
We study flavor-conserving radiative decays of double-heavy baryons using a manifestly Lorentz covariant constituent three-quark model. Decay rates are calculated and compared to each other in the full theory, keeping masses finite, and also in the heavy quark limit. We discuss in some detail hyperfine mixing effects.
117141257
Multiquark states in the covariant quark confinement model
This talk reviews the last applications of the covariant quark model for studying the properties of the multiquark states: B_s-meson (quark-antiquark state), light baryons (three-quark states) and tetraquark (four-quark state). The form factors of the B(B_s)-> P(V)-transitions are evaluated in the full kinematical region of momentum transfer squared. The widths of some B_s-nonleptonic decays are calculated. The static properties of the proton and neutron, and the \Lambda-hyperon (magnetic moments and charge radii) and the behavior of the nucleon form factors at low momentum transfers are described. The consequences of treating the X(3872) meson as a tetraquark bound state are explored. The decay widths of the observed channels X->J/\psi+2\pi (3\pi) and X-> \bar D^0 + D^0+\pi^0 via the intermediate off--shell states X-> J/\psi+\rho(\omega) and X-> \bar D + D^* are calculated. Its one-photon decay X-> \gamma+ J/\psi is also analyzed.
18648204
Decay Constants and Semileptonic Form Factors of Pseudoscalar Mesons 1
AbstractA relativistic constituent quark model is adopted to give an uniﬁed description of the leptonic andsemileptonic decays of pseudoscalar mesons (π, K, D, D s , B, B s ). The calculated leptonic decayconstants and form factors are found to be in good agreement with available experimental data andthe results of other approaches. Eventually, the model is found to reproduce the scaling behavioursof spin-ﬂavor symmetry in the heavy-quark limit. 1 Introduction Semileptonic decays of pseudoscalar mesons allow to evaluate the elements of the Cabibbo–Kobayashi–Maskawa (CKM) matrix, which are fundamental parameters of the Standard Model. The decay K → πeνprovides the most accurate determination of V us , the semileptonic decays of D and B mesons, D →K(K ∗ )lν, B → D(D ∗ )lν and B → π(ρ)lν, can be used to determine |V cs |, |V cb | and |V ub |, respectively.This program can be performed if the non-perturbative QCD eﬀects, which are parameterized by theform factors, are known. Up to now, these form factors cannot be evaluated from ﬁrst principles, thusmodels, more or less connected with QCD, are usually considered for this purpose. Here we discuss arelativistic quark model [1], previously used to study the baryon form factors [2].This model is based on an eﬀective Lagrangiandescribingthe coupling ofmesons with their constituentquarks. The physical processes are described by the one-loop quark diagrams and meson-quark verticesrelated to the Bethe-Salpeter amplitudes. In principle, the vertex functions and quark propagatorsshouldbe given by the Bethe-Salpeter and Dyson-Schwinger equations, respectively. This kind of analysis isprovided by the Dyson-Schwinger Equation (DSE) studies [3] and an uniﬁed description of light andheavy meson observables was carried out in [4, 5]. Here, instead, we use free propagators for constituentquarks and consider a Gaussian vertex function as Bethe-Salpeter conﬁning function. The adjustableparameters, the widths of Bethe-Salpeter amplitudes in momentum space, and the constituent quarkmasses, are determined from the best ﬁt of available experimental data and some lattice simulations.Our results are in good agreement with experimental data and other approaches. We also reproduce thespin-ﬂavor symmetry relations and scaling for leptonic decay constants and semileptonic form factors inthe heavy-quark limit [6].An approach similar to the one presented here, can be found in [7]. That model is based on meson-quark interactions, so the mesonic transition amplitudes are described by diagrams with heavy mesonsattached to quark loops. The free propagator has been used for light quarks, while the quark propagatorobtained in the heavy-quark limit has been adopted for heavy quarks.