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R. N. Faustov

Publications and source records attributed to R. N. Faustov.

At least 91 records · Page 5Linked to original sources
arXiv2003

Nuclear structure corrections in the energy spectra of electronic and muonic deuterium

The one-loop nuclear structure corrections of order (Z alpha)^5 to the Lamb shift and hyperfine splitting of the deuterium are calculated. The contribution of the deuteron structure effects to the isotope shift (ep)-(ed), (mu p)-(mu d) in the interval (1S - 2S) is obtained on the basis of modern experimental data on the deuteron electromagnetic form factors. The comparison with the similar contributions to the Lamb shift for electronic and muonic hydrogen shows, that the relative contribution due to the nucleus structure increases when passing from the hydrogen to the deuterium.

hep-ph↗
arXiv2003

Properties of heavy quarkonia and B_c mesons in the relativistic quark model

The mass spectra and electromagnetic decay rates of charmonium, bottomonium and B_c mesons are comprehensively investigated in the relativistic quark model. The presence of only heavy quarks allows the expansion in powers of their velocities. All relativistic corrections of order v^2/c^2, including retardation effects and one-loop radiative corrections, are systematically taken into account in the computations of the mass spectra. The obtained wave functions are used for the calculation of radiative magnetic dipole (M1) and electric dipole (E1) transitions. It is found that relativistic effects play a substantial role. Their account and the proper choice of the Lorentz structure of the quark-antiquark interaction in a meson is crucial for bringing theoretical predictions in accord with experimental data. A detailed comparison of the calculated decay rates and branching fractions with available experimental data for radiative decays of charmonium and bottomonium is presented. The possibilities to observe the currently missing spin-singlet S and P states as well as D states in bottomonium are discussed. The results for B_c masses and decays are compared with other quark model predictions.

hep-ph↗
arXiv2003

Two-photon decay rates of heavy quarkonia in the relativistic quark model

Two-photon decay rates of pseudoscalar, scalar and tensor states of charmonium and bottomonium are calculated in the framework of the relativistic quark model. Both relativistic effects and one-loop radiative corrections are taken into account. The obtained results are compared with other theoretical predictions and available experimental data.

hep-ph↗
arXiv2002

One-loop corrections of order (Z alpha)^6m_1/m_2, (Z alpha)^7 to the muonium fine structure

The corrections of order (Z alpha)^6m_1/m_2 and (Z alpha)^7 from one-loop two-photon exchange diagrams to the energy spectra of the hydrogenic atoms are calculated with the help of the Taylor expansion of corresponding integrands. The method of averaging the quasipotential over the wave functions in the d-dimensional coordinate space is formulated. The numerical values of the obtained contributions to the fine structure of muonium, hydrogen and positronium are presented.

hep-ph↗
arXiv2002

Pseudoscalar pole terms contributions to hadronic light-by-light corrections to the muonium hyperfine splitting

The contribution of pseudoscalar pole diagrams to the hadronic light-by-light corrections of order alpha^3 E_F to the ground state hyperfine splitting in hydrogenic atom is calculated in the pseudoscalar pole terms approximation. The vector dominance model for the form factor of the transition of a pseudoscalar meson into two photons is used. With the account of new experimental data on the cross sections sigma (e^+e^-\to ρ, ω\to π^0(η)γ) in the SND and CMD-2 experiments some other hadronic corrections to the muonium hyperfine splitting are calculated.

hep-ph↗
arXiv2002

Charm mass corrections to the bottomonium mass spectrum

The one-loop corrections to the bottomonium mass spectrum due to the finite charm mass are evaluated in the framework of the relativistic quark model. The obtained corrections are compared with the results of perturbative QCD.

hep-ph↗
arXiv2002

Radiative M1-decays of heavy-light mesons in the relativistic quark model

Radiative magnetic dipole decays of heavy-light vector mesons into pseudoscalar mesons V -> Pγare considered within the relativistic quark model. The light quark is treated completely relativistically, while for the heavy quark the 1/m_Q expansion is used. It is found that relativistic effects result in a significant reduction of decay rates. Comparison with previous predictions and recent experimental data is presented.

hep-ph↗
arXiv2002

Decay constants of heavy-light mesons in the relativistic quark model

The decay constants of pseudoscalar and vector heavy-light mesons are calculated in the framework of the relativistic quark model with the completely relativistic treatment of the light quark. It is argued that relativistic effects play a significant role. Good agreement of the model predictions with recent lattice and QCD sum rule calculations as well as available experimental data is found.

hep-ph↗
arXiv2002

Mass spectra of doubly heavy baryons in the relativistic quark model

Mass spectra of baryons consisting of two heavy (b or c) and one light quarks are calculated in the framework of the relativistic quark model. The light quark-heavy diquark structure of the baryon is assumed. Under this assumption the ground and excited states of both the diquark and quark-diquark bound system are considered. The quark-diquark potential is constructed. The light quark is treated completely relativistically, while the expansion in the inverse heavy quark mass is used revealing the close similarity with the mass spectra of B and D mesons. We find that the relativistic treatment of the light quark plays an important role. The level inversion of the p-wave excitations of the light quark in doubly heavy baryons is discussed.

hep-ph↗
arXiv2001

Heavy quark potential and mass spectra of heavy mesons

The relativistic quark model is presented. The quark-antiquark potential for the Schroedinger-like equation is constructed with the account of retardation effects and one-loop radiative corrections. It consists of the one-gluon exchange part and the confining part which is the mixture of the Lorentz scalar and Lorentz vector contributions. The latter contains both the Dirac and Pauli terms. In the v^2/c^2 approximation the mass spectra of heavy quarkonia (charmonium and bottomonium) are calculated in good agreement with experiment. In the case of heavy-light mesons (B and D) the light quark is treated completely relativistically and only the expansion in the inverse heavy quark mass is used. The mass spectra of the ground and excited states of D, D_s, B, B_s mesons are calculated. They exhibit some features of the so-called ``level inversion''. The obtained results are generally in accord with experimental data. Still there exist some discrepancies between measurements of different collaborations.

hep-ph↗
arXiv2001

Form factors of heavy-to-light B decays at large recoil

General relations between the form factors of B decays to light mesons are derived using the heavy quark and large recoil expansion. On their basis the complete account of contributions of second order in the ratio of the light meson mass to the large recoil energy is performed. Both ground and excited final meson states are considered. It is shown that most of the known form factor relations remain valid after the inclusion of quadratic mass corrections. The validity of some of such relations requires additional equalities for the helicity amplitudes. It is found that all these relations and equalities are fulfilled in the relativistic quark model based on the quasipotential approach in quantum field theory. The contribution of 1/m_b corrections to the branching fraction of the rare radiative B decay is discussed.

hep-ph↗
arXiv2001

Rare radiative B decays to orbitally excited K mesons

The exclusive rare radiative B meson decays to orbitally excited axial-vector mesons K_1^*(1270), K_1(1400) and to the tensor meson K_2^*(1430) are investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. These decays are considered without employing the heavy quark expansion for the s quark. Instead the s quark is treated to be light and the expansion in inverse powers of the large recoil momentum of the final K^{**} meson is used to simplify calculations. It is found that the ratio of the branching fractions of rare radiative B decays to axial vector K^*_1(1270) and K_1(1400) mesons is significantly influenced by relativistic effects. The obtained results for B decays to the tensor meson K_2^*(1430) agree with recent experimental data from CLEO.

hep-ph↗
arXiv2001

Exclusive weak B decays to excited meson states

Exclusive semileptonic B decays to radially excited charmed mesons and rare radiative B decay to the orbitally excited tensor K_2^*(1430) meson are investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The heavy quark expansion is applied for the semileptonic B\to D^{(*)}'eνdecays. Both relativistic and the 1/m_Q corrections are found to play an important role for these decays and substantially modify results. For rare radiative B -> K_2^*(1430)γdecay such an expansion is not used for the s quark. Instead we apply the expansion in inverse powers of large recoil momentum of final K_2^*(1430) meson. The calculated branching fraction BR(B -> K_2^*(1430)γ)=(1.7\pm 0.6)\times 10^{-5} as well as the ratio BR(B -> K_2^*(1430)γ)/BR(B -> K^*(892)γ)=0.38\pm 0.08 are found to be in a good agreement with recent experimental data from CLEO.

hep-ph↗
arXiv2000

Magnetic moment of the two-particle bound state in quantum electrodynamics

We have formulated the quasipotential method for the calculation of the relativistic and radiative corrections to the magnetic moment of the two-particle bound state in the case of particles with arbitrary spin. It is shown that the g-factors of bound particles contain $O(α^2)$ terms depending on the particle spin. Numerical values for the g-factors of the electron in the hydrogen atom and deuterium are obtained.

hep-ph↗
arXiv2000

Rare radiative B decay to the orbitally excited K_2^*(1430) meson

The exclusive rare radiative B meson decay to the orbitally excited tensor K_2^*(1430) meson is investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The calculated branching ratio BR(B --> K_2^*(1430)γ)=(1.7\pm 0.6)\times 10^{-5} as well as the ratio BR(B --> K_2^*(1430)γ)/BR(B --> K^*(892)γ)=0.38\pm 0.08 is found in a good agreement with recent experimental data from CLEO.

hep-ph↗