2325056
A non-geometrical approach to quantum gravity
Some results of author's work in a non-geometrical approach to quantum gravity are reviewed here, among them: a quantum mechanism of classical gravity giving a possibility to compute the Newton constant; asymptotic freedom at short distances; interaction of photons with the graviton background leading to the important cosmological consequences; the time delay of photons due to interactions with gravitons; deceleration of massive bodies in the graviton background which may be connected with the Pioneer anomaly and with the problem of dark matter.
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.
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.
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.
120906293
Decay properties of double heavy baryons
We study the semileptonic decays of double heavy baryons using a manifestly Lorentz covariant constituent three‐quark model. We present complete results on transition form factors between double‐heavy baryons for finite values of the heavy quark/baryon masses and in the heavy quark symmetry limit which is valid at and close to zero recoil. Decay rates are calculated and compared to each other in the full theory, keeping masses finite, and also in the heavy quark limit.
3052387
Integrating out strange quarks in ChPT
We study three flavour chiral perturbation theory in a limit where the strange quark mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of two–flavour chiral perturbation theory. In this case, the theory reduces to the one of SU(2)L × SU(2)R. Through this reduction, one can work out the strange quark mass dependence of the LECs in the two–flavour case. We present the pertinent relations at two–loop order for F,B and li.
118350677
Cosmological dynamics of fourth-order gravity with a Gauss-Bonnet term
We consider the cosmological dynamics of fourth-order gravity with both f(R) and Φ(G) corrections to the Einstein gravity (G is the Gauss-Bonnet invariant). The particular case for which both terms are equally important on power-law solutions is described. These solutions and their stability are studied using the dynamic system approach. We also discuss the condition of existence and stability of a de Sitter solution in a more general situation of power-law f and Φ.
5573876
Heavy meson observables and Dyson Schwinger equations.
Dyson-Schwinger equation (DSE) studies show that the b-quark mass-function is approximately constant, and that this is true to a lesser extent for the c-quark. This observation provides the basis for a study of the leptonic and semileptonic decays of heavy pseudoscalar mesons using a ''heavy-quark'' limit of the DSES, which, when exact, reduces the number of independent form factors. Semileptonic decays with light mesons in the final state are also accessible because the DSES provide a description of light-quark propagation characteristics and light-meson structure. A description of B-meson decays is straightforward, however, the study of decays involving the D-meson indicates that c-quark mass-corrections are quantitatively important.
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.