119595470
Discrete Symmetries Underlying Some Continuous Ones: Two Examples From Gravity And Particle Physics
Two examples, not connected at present, from author's papers (Nuovo Cim., 1992, v.105A, p.77 [hep-th/0207210] and GRG, 1999, v.31, p.1431 [gr-qc/0207017]) are considered here in which a physical model has discrete symmetries and additional non-observable coordinates or parameters. Then it is possible to introduce some apparent continuous symmetries of the model for an observer which cannot know values of these additional quantities.
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.
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.
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.
10775423
Semileptonic Decays of Bottom and Charm Baryons within Relativistic Quark Model
The results for observables of semileptonic decays of bottom and charm baryons (Isgur-Wise functions, decay rates, distributions, asymmetry parameters) are given within relativistic quark model. A comparison with recent experimental data (CLEO Collaboration) is made.
18746577
Heavy Baryons in a Relativistic Quark Model with a Nonlocal Interaction of Light Quarks
Semileptonic decays of bottom and charm baryons are considered within a relativistic three-quark model with the Gaussian shape for the baryon-three-quark vertex and standard quark propagators.
119687382
Rare decay pi0 ---> e+ e-: Theory confronts KTeV data
Within the dispersive approach to the amplitude of the rare decay ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ the nontrivial dynamics is contained only in the subtraction constant. We express this constant, in the leading order in $({m}_{e}/\ensuremath{\Lambda}{)}^{2}$ perturbative series, in terms of the inverse moment of the pion transition form factor given in symmetric kinematics. By using the CELLO and CLEO data on the pion transition form factor given in asymmetric kinematics, the lower bound of the decay branching ratio is found. The restrictions following from QCD allow us to make a quantitative prediction for the branching $B({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})=(6.2\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\cdot\else\textperiodcentered\fi{}{10}^{\ensuremath{-}8}$ which is $3\ensuremath{\sigma}$ below the recent KTeV measurement. We confirm our prediction by using the quark models and phenomenological approaches based on the vector meson dominance. The decays $\ensuremath{\eta}\ensuremath{\rightarrow}{l}^{+}{l}^{\ensuremath{-}}$ are also discussed.
116517338
The Low Energy Physics of Pion in the Relativistic Model with a Separable Interaction
A Lagrangian formulation of the Nambu-Jona-Lasinio model with separable interaction is given. The electromagnetic interaction is introduced in a non-minimal way to the nonlocal quark current. Various choices of the vertex form factors characterizing the composite structure of mesons and baryon are investigated. W’e find that the physical observables depend very weakly on form factor shapes. PACS. 12.39.Fe - Chiral Lagrangians.
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.