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V. E. Lyubovitskij

Publications and source records attributed to V. E. Lyubovitskij.

105 records · Page 6Linked to original sources
arXiv1998

Exclusive nonleptonic bottom to charm baryon decays including nonfactorizable contributions

Exclusive nonleptonic decays of bottom baryons to charm baryons and pseudoscalar light mesons are analyzed within a relativistic three-quark model. We include factorizing as well as nonfactorizing contributions to the decay amplitudes. The total contribution of the nonfactorizing diagrams amount up to 30% of the factorizing contributions in amplitude. We present detailed predictions for rates and asymmetry parameters.

hep-ph↗
arXiv1998

Exclusive Nonleptonic Decays of Bottom and Charm Baryons in a Relativistic Three-Quark Model: Evaluation of Nonfactorizing Diagrams

Exclusive nonleptonic decays of bottom and charm baryons are studied within a relativistic three-quark model with a Gaussian shape for the momentum dependence of the baryon-three-quark vertex. We include factorizing as well as nonfactorizing contributions to the decay amplitudes. For heavy-to-light transitions Q -> q u d the total contribution of the nonfactorizing diagrams amount up to approximately 60% of the factorizing contributions in amplitude, and up to approximately 30% for b -> c u d transitions. We calculate the rates and the polarization asymmetry parameters for various nonleptonic decays and compare them to existing data and to the results of other model calculations.

hep-ph↗
arXiv1998

Perturbative framework for the pi(+)pi(-) atom

The perturbative framework is developed for the calculation of the pi(+)pi(-) atom characteristics on the basis of the field-theoretical Bethe-Salpeter approach. A closed expression for the first-order correction to the pi(+)pi(-) atom lifetime has been obtained.

hep-ph↗
arXiv1997

Weak Decays of Heavy Baryons in the Covariant Quasipotential Approach

Bethe-Salpeter approach has been applied to the study of b --> c transitions both for heavy mesons and heavy baryons. Meson and baryon IW functions are calculated on the equal footing. A reasonable agreement with the experimental data for heavy to heavy semileptonic transitions has been obtained.

hep-ph↗
arXiv1997

The gamma(*) pi(0) -> gamma form factor

The gamma(*) pi(0) -> gamma form factor is obtained within the Lagrangian quark model with separable interaction known to provide a good description of the pion observables at low energies. The pion-quarks vertex is chosen in a Gaussian form. The form factor obtained is close to the available experimental data and reaches smoothly the Brodsky-Lepage limit at Q2 = 10 GeV2.

hep-ph↗
arXiv1996

Nucleon Form Factors in a Relativistic Three-Quark Model

We report the calculation of electromagnetic form factors of nucleons within a relativistic three-quark model with Gaussian shape for the nucleon-quark vertex. The allowed region for two adjustable parameters, the range parameter $Λ_N$ in the Gaussian and the constituent quark mass $m_q$, is obtained from fitting the data for magnetic moments and electromagnetic radii of nucleons. It is found that their values calculated with $m_q$=420 MeV and $Λ_N$=1.25 GeV agree very well with the experimental data. It is turned out that the electric proton and magnetic nucleon form factors fall faster than the dipole fit of the experimental data for momentum transfers $0\le Q^2\le 1$ GeV$^2$.

hep-ph↗
arXiv1996

Heavy Baryon Transitions in a Relativistic Three-Quark Model

Exclusive semileptonic decays of bottom and charm baryons are considered within a relativistic three-quark model with a Gaussian shape for the baryon-three-quark vertex and standard quark propagators. We calculate the baryonic Isgur-Wise functions, decay rates and asymmetry parameters.

hep-ph↗
arXiv1996

Lifetime of $(π^+π^-)$ Atom: Analysis of the Role of Strong Interactions

The expression for the $(π^+π^-)$ atom lifetime is derived within the Bethe-Salpeter approach. First-order perturbative corrections due to the contribution of strong interactions are taken into account. It is demonstrated that the atom lifetime can be expressed in terms of the solutions of the Coulombic problem (the wave function of the $1S$ state at the origin $Ψ_1(0)$, the binding energy of the $S$-state $E_1$), the difference of the $S$-wave $ππ$ scattering lengths and the energy shift $ΔE_1$ of the level due to the strong interactions: $ 1/(τ_{1})\sim (a^0_0-a^2_0)^2 |Ψ_1(0)|^2 (1-(9ΔE_1)/(8E_1))$

hep-ph↗
arXiv1996

Electromagnetic form factors of nucleons in a relativistic three-quark model

We report the calculation of electromagnetic form factors of nucleons within a relativistic three-quark model with Gaussian shape for the nucleon-quark vertex. The allowed region for two adjustable parameters, the range parameter $Λ_N$ in the Gaussian and the constituent quark mass $m_q$, is obtained from fitting the data for magnetic moments and electromagnetic radii of nucleons. The shapes of electric and magnetic nucleon form factors calculated in this approach with the central parameters $m_q$=420 MeV and $Λ_N$=1.25 GeV are close to the data for momentum transfers $0\le Q^2\le 1$ GeV$^2$

hep-ph↗
arXiv1995

Isgur-Wise Function and Observables of $Λ_b$ Baryon

In connection with planned experiments devoted to investigation of semileptonic decays of beauty baryons Isgur-Wise function and observables of $Λ_b$ baryon (decay rates and distributions, leptonic spectra and asymmetry parameters) are calculated in the framework of diquark model with taking into account of infrared regime for heavy quark.

hep-ph↗
arXiv1994

Relativistic Quark Model Based Description of Low Energy NN Scattering

A description of the NN scattering is constructed starting from the $π, η, η'$ pseudoscalar-, the $ρ, ϕ, ω$ vector-, and the $\varepsilon(600), a_0, f_0(1400)$ scalar - meson-nucleon coupling constants, which we obtain within a relativistic quark model. Working within the Blankenbecler-Sugar-Logunov-Tavkhelidze quasipotential dynamics we thus describe the NN phase shifts in a relativistically invariant way. In this procedure we use the phenomenological form factor cutoff masses and the effective $\varepsilon$ and $ω$ meson-nucleon coupling constants, only. The comparison of our NN phase shifts to the both empirical data and the Bonn OBEP fit shows good agreement -- the ratio of the $χ^2$ for the present results to the $χ^2$ for Bonn OBEP description is 1.2.

hep-ph↗