Self-energy correction to the bound-electron g factor in H-like ions

The one-loop self-energy correction to the 1s electron g factor is evaluated to all orders in Z\alpha with an accuracy, which is essentially better than that of previous calculations of this correction. As a result, the uncertainty of the theoretical prediction for the bound-electron g factor in H-like carbon is reduced by a factor of 3. This improves the total accuracy of the recent electron-mass determination [Beier et al. Phys. Rev. Lett. 88, 011603 (2002)]. The new value of the electron mass is found to be m_e = 0.000 548 579 909 3(3) u

The light-by-light contribution to the muon anomalous magnetic moment from the axial-vector mesons exchanges within the nonlocal quark model

The contribution of axial-vector mesons to the muon's anomalous magnetic moment through a light-by-light process is considered within a nonlocal quark model. The model is based on a four-quark interaction with scalar--pseudoscalar and vector--axial-vector sectors. While the transverse component of the axial-vector corresponds to a spin-1 particle, the unphysical longitudinal component is mixed with a pseudoscalar meson. The model parameters are re-fitted to the pion properties in the presence of pi-a_1 mixing. The obtained estimation for the light-by-light contribution of a_1+f_1 mesons is (3.6+-1.8)*10^{-11}.Comment: 18 pages, 10 figures, final version accepted for publication in Physical Review

Muonic hydrogen ground state hyperfine splitting

Corrections of orders alpha^5, alpha^6 are calculated in the hyperfine splitting of the muonic hydrogen ground state. The nuclear structure effects are taken into account in the one- and two-loop Feynman amplitudes by means of the proton electromagnetic form factors. The modification of the hyperfine splitting part of the Breit potential due to the electron vacuum polarization is considered. Total numerical value of the 1S state hyperfine splitting 182.638 meV in the (mu p) can play the role of proper estimation for the corresponding experiment with the accuracy 30 ppm.Comment: 18 pages, Talk presented at the 11th Lomonosov Conference on Elementary Particle Physics, Moscow State University, August 200

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.Comment: Talk given at the XVIth International Workshop High-Energy Physics and Quantum Field Theory (QFTHEP2001), Moscow, Russia, 6-12 Sep 2001, 12 pages, REVTE

Hadronic Production of Doubly Charmed Baryons via Charm Exitation in Proton

The production of baryons containing two charmed quarks Xi_cc in hadronic interactions at high energies and large transverse momenta is considered. It is supposed, that Xi_cc-baryon is formed during a non-perturbative fragmentation of the (cc)-diquark, which was produced in the hard process of $c$-quark scattering from the colliding protons: c+c -> (cc) +g. It is shown that such mechanism enhances the expected doubly charmed baryon production cross section on Tevatron and LHC colliders approximately 2 times in contrast to predictions, obtained in the model of gluon - gluon production of (cc)-diquarks in the leading order of perturbative QCD.Comment: LaTeX2e, 13 pages plus 4 fig. using revtex4.sty, epsfig.sty. Talk was presented at International Seminar on Physics of Fundamental Interactions in ITEP, Moscow, Russia, November 27 - December 1, 200

Changes to Species Diversity of Vegetation Communities during Restorative Successions in Different Types of Forests

In this work, we study changes in species diversity of vegetation communities during restorative successions at logging sites in different types of forests, using the South Ural region as an example. Data from 180 geobotanical relevés of logging sites and secondary forests of different ages of the four main types of the South Ural region forest communities (cool-temperate dark-coniferous, nemoral broad-leaved, hemiboreal light-coniferous and boreal light-coniferous forests) were analyzed. Trends in changes to species diversity manifest themselves in different ways during each stage of the ‘native forest – logging – secondary forest’ succession sequence. In broad-leaved and cool-temperate dark-coniferous forests, changes in species diversityfollow the parabolic trajectory during restorative successions at clear-cutting sites; in other words, the diversity initially increases and then decreases during the progress of the succession. This is caused by the introduction of invasive synanthropic species during the early stages of the succession. The level of species diversity at clear-cutting sites in hemiboreal light-coniferous forests barely changes due to the rapid expansion of reed grass, which prevents the invasion of synanthropic species in the logging areas. Keywords: species diversity, restorative succession, logging, secondary forests, synanthropic specie