Recoil corrections in the hydrogen isoelectronic sequence

A version of the Bethe-Salpeter equation appropriate for calculating recoil corrections in highly charged hydrogenlike ions is presented. The nucleus is treated as a scalar particle of charge Z, and the electron treated relativistically. The known recoil corrections of order $m^2/M(Z\alpha)^4$ are derived in both this formalism and in NRQED

Composite Skyrme Model with Vector Mesons

We study the composite Skyrme model, proposed by Cheung and G\"{u}rsey, introducing vector mesons in a chiral Lagrangian. We calculate the static properties of baryons and compare with results obtained from models without vector mesons.Comment: LaTeX, 9 pages, 3 figures, to be published in Phys. Rev.

alpha^2 corrections to parapositronium decay: a detailed description

We present details of our recent calculation of alpha^2 corrections to the parapositronium decay into two photons. These corrections are rather small and our final result for the parapositronium lifetime agrees well with the most recent measurement. Implications for orthopositronium decays are briefly discussed.Comment: 18 pages, late

The "recoil" correction of order mα6m \alpha^6 to hyperfine splitting of positronium ground state

The "recoil" correction of order $m \alpha^6$ to the hyperfine splitting of positronium ground state was found. The formalism employed is based on the noncovariant perturbation theory in QED. Equation for two-particle component of full (many-body) wave function is used, in which effective Hamiltonian depends on the energy of a system. The effective Hamiltonian is not restricted to the nonrelativistic region, so there is no need in any regularization. To evaluate integrals over loop momenta, they are divided into "hard" and "soft" parts, coming from large and small momenta respectively. Soft contributions were found analytically, and hard ones are evaluated by numerical integration. Some soft terms due to the retardation cancel each other. To calculate the "hard" contributions, a great number of noncovariant graphs is replaced by only a few covariant ones. The hard contribution was found in two ways. The first way is to evaluate contributions of separate graphs, using the Coulomb gauge. The second one is to calculate full hard contribution as a whole using the Feynman gauge. The final result for the "recoil" correction is 0.381(6) m\al^6 and agrees with those of previous papers. Diagram-to-diagram comparison with the revised results of Adkins&Sapirstein was done. All the results agree, so the "recoil" correction is now firmly established. This means a considerable disagreement with the experimental data.Comment: 28 pages, latex including latex figure

The Single Photon Annihilation Contributions to the Positronium Hyperfine Splitting to Order meα6m_e\alpha^6

The single photon annihilation contributions for the positronium ground state hyperfine splitting are calculated analytically to order $m_e\alpha^6$ using NRQED. Based on intuitive physical arguments the same result can also be determined by a trivial calculation using results from existing literature. Our result completes the hyperfine splitting calculation to order $m_e\alpha^6$. We compare the theoretical prediction with the most recent experimental measurement.Comment: 8 pages, latex, two eps figures include

Order alpha^3 ln(1/alpha) Corrections to Positronium Decays

The logarithmically enhanced alpha^3 ln(1/alpha) corrections to the para- and orthopositronium decay widths are calculated in the framework of dimensionally regularized nonrelativistic quantum electrodynamics.In the case of parapositronium, the correction is negative, approximately doubles the effect of the leading logarithmic alpha^3 ln^2(1/alpha) one, and is comparable to the nonlogarithmic O(alpha^2) one. As for orthopositronium, the correction is positive and almost cancels the alpha^3 ln^2(1/alpha) one. The uncertainties in the theoretical predictions for the decay widths are reduced.Comment: 10 pages (Latex); missing term added, corrected coefficient B_p used, numerical results insignificantly change

Semi-classical equation of state and specific heats for neutron-star inner crust with proton shell corrections

An approach to the equation of state for the inner crust of neutron stars based on Skyrme-type forces is presented. Working within the Wigner-Seitz picture, the energy is calculated by the TETF (temperature-dependent extended Thomas-Fermi) method, with proton shell corrections added self-consistently by the Strutinsky-integral method. Using a Skyrme force that has been fitted to both neutron matter and to essentially all the nuclear mass data, we find strong proton shell effects: proton numbers $Z$ = 50, 40 and 20 are the only values possible in the inner crust, assuming that nuclear equilibrium is maintained in the cooling neutron star right down to the ambient temperature. Convergence problems with the TETF expansion for the entropy, and our way of handling them, are discussed. Full TETF expressions for the specific heat of inhomogeneous nuclear matter are presented. Our treatment of the electron gas, including its specific heat, is essentially exact, and is described in detail.Comment: 41 pages, 6 figure

Neocarchean carbonate-associated sulfate records positive Δ^(33)S anomalies

Mass-independent fractionation of sulfur isotopes (reported as Δ^(33S) recorded in Archean sedimentary rocks helps to constrain the composition of Earth’s early atmosphere and the timing of the rise of oxygen ~2.4 billion years ago. Although current hypotheses predict uniformly negative Δ^(33)S for Archean seawater sulfate, this remains untested through the vast majority of Archean time.We applied x-ray absorption spectroscopy to investigate the low sulfate content of particularly well-preserved Neoarchean carbonates and mass spectrometry to measure their Δ^(33)S signatures. We report unexpected, large, widespread positive Δ^(33)S values from stratigraphic sections capturing over 70 million years and diverse depositional environments. Combined with the pyrite record, these results show that sulfate does not carry the expected negative Δ^(33)S from sulfur mass-independent fractionation in the Neoarchean atmosphere

Order \alpha^2 corrections to the decay rate of orthopositronium

Order \alpha^2 corrections to the decay rate of orthopositronium are calculated in the framework of nonrelativistic QED. The resulting contribution is found to be in significant disagreement with one set of experimental measurements though another experiment is in agreement with theory.Comment: 7 pages, 1 figur