Related papers: Pionium lifetime corrections
The pionium decay width is evaluated in the framework of chiral perturbation theory and the relativistic bound state formalism of constraint theory. Corrections of order O(\alpha) are calculated with respect to the conventional lowest-order…
Pionium lifetime corrections to the nonrelativistic formula are calculated in the framework of the quasipotential-constraint theory approach. The calculation extends an earlier evaluation, made in the scheme of standard chiral perturbation…
Next to leading order contributions to the pionium lifetime are considered within non-relativistic effective field theory. A more precise determination of the coupling constants is then needed in order to be consistent with the relativistic…
The lowest order QED radiative corrections to the cross-section of the recharged process of transition of two charged pions to two neutral ones and to the pionium life time are calculated in frames of scalar QED. It is argued that the…
The pionium lifetime is calculated in the framework of the quasipotential-constraint theory approach, including the sizable electromagnetic corrections. The framework of generalized chiral perturbation theory allows then an analysis of the…
The relationship between the pionium lifetime and the $\pi\pi$ scattering lengths is established, including the sizable electromagnetic corrections. The bound state formalism that is used is that of constraint theory which provides a…
Recently, much work has been devoted to the calculation of order $\alpha$ corrections to the decay rate of pionium, the $\pi^+ \pi^-$ bound state. In previous calculations, nonrelativistic QED corrections were neglected since they start at…
We review the existing theoretical approaches to the study of the observables of hadronic atoms. In the relativistic perturbative approach based on the Bethe-Salpeter equation and Chiral Perturbation Theory we derive the general expression…
Some atomic decays of elementary particles with pionium ($\pi^+\pi^-$-dimesoatom) in the final state are considered. Only for K-meson atomic decays are the corresponding branching ratios big enough to make their experimental study…
The relativistic perturbative approach based on the Bethe-Salpeter (BS) equation is developed for the study of the characteristics of the hadronic pi+ pi- atom. The general expression for the atom lifetime is derived. Lowest-order…
We calculate in chiral perturbation theory the double-pion photoproduction processes $\pi^-\gamma \to \pi^- \pi^0\pi^0$ and $\pi^-\gamma\to \pi^+\pi^-\pi^-$ at low energies. At leading order these reactions are governed by the chiral…
We calculate the radiative corrections of order O(alpha E_e/m_N) as next-to-leading order corrections in the large nucleon mass expansion to Sirlin's radiative corrections of order O(alpha/pi) to the neutron lifetime. The calculation is…
Hadronic (Pi+Pi-) atom is studied in the relativistic perturbative approach based on the Bethe-Salpeter equation. The general expression for the atom lifetime is derived. Lowest-order corrections to the relativistic Deser-type formula for…
We construct an effective Lagrangian for interacting pions with non-relativistic energies. The coupling constants can be expressed in terms of the different scattering lengths and slopes. When used in the calculation of the pionium decay…
Recently, the O(alpha) and O(alpha^3 ln(alpha)) radiative corrections to the orthopositronium lifetime have been presented in closed analytical form, in terms of basic irrational numbers that can be evaluated numerically to arbitrary…
The electromagnetic corrections to the low energy scattering amplitude involving charged pions only are investigated at leading and next-to-leading orders in the two-flavour chiral expansion. As an application, the corresponding variation…
The order $\alpha^4 R_{\infty}$ corrections to positronium $P$ levels are found. The calculation is reduced to the ordinary perturbation theory for the nonrelativistic Schr\"odinger equation. The perturbation operators have the Breit-type…
Leading-order electromagnetic loop corrections to the one-pion-exchange potential are computed within the framework of chiral perturbation theory. These corrections generate an effective nucleon-nucleon potential, $V_{\pi \gamma}$, which…
The one-electron quantum-electrodynamic corrections to the magnetic-dipole transition amplitude between the fine-structure levels (1s^2 2s^2 2p) ^2P_3/2 - ^2P_1/2 in boronlike ions are calculated to all orders in (\alpha Z). The results…
An analysis of electromagnetic corrections to the (dominant) octet K -> pi pi hamiltonian using chiral perturbation theory is carried out. Relative shifts in amplitudes at the several per cent level are found.