Akaki Rusetsky

Spectrum and decays of kaonic hydrogen

Abstract.By using the non-relativistic effective Lagrangian approach to bound states, a complete expression for the isospin-breaking corrections to the energy levels and the decay widths of kaonic hydrogen is obtained up-to-and-including

Cusps in K→3π decays

O(\alpha,m_d-m_u)

Unitarized Chiral Perturbation Theory in a finite volume: Scalar meson sector

in QCD. It is demonstrated that, although the leading-order corrections at

A Method to measure the antikaon-nucleon scattering length in lattice QCD

O(\alpha^{1/2},(m_d-m_u)^{1/2})

Hadronic atoms in QCD + QED

emerging due to the unitarity cusp are huge, they can be expressed solely in terms of the KN S-wave scattering lengths. Consequently, at leading order, it is possible to derive parameter-free modified Deser-type relations, which can be used to extract the scattering lengths from the hadronic atom data.

Scalar mesons in a finite volume

Abstract The pion mass difference generates a pronounced cusp in K → 3 π decays. As has recently been pointed out by Cabibbo and Isidori, an accurate measurement of the cusp may allow one to pin down the S-wave ππ scattering lengths to high precision. Here, we present and illustrate an effective field theory framework that allows one to determine the structure of this cusp in a straightforward manner. The strictures imposed by analyticity and unitarity are respected automatically.

Three particles in a finite volume

We develop a scheme for the extraction of the properties of the scalar mesons f0(600) , f0(980) , and a0(980) from lattice QCD data. This scheme is based on a two-channel chiral unitary approach with fully relativistic propagators in a finite volume. In order to discuss the feasibility of finding the mass and width of the scalar resonances, we analyze synthetic lattice data with a fixed error assigned, and show that the framework can be indeed used for an accurate determination of resonance pole positions in the multichannel scattering.

Resonance properties from the finite-volume energy spectrum

Abstract We propose a method to determine the isoscalar K ¯ N scattering length on the lattice. Our method represents the generalization of Luschers approach in the presence of inelastic channels (complex scattering length). In addition, the proposed approach allows one to find the position of the S-matrix pole corresponding the Λ ( 1405 ) resonance.

Isospin breaking in K l4 decays

Abstract We review the theory of hadronic atoms in QCD+QED, based on a non-relativistic effective Lagrangian framework. We first provide an introduction to the theory, and then describe several applications: meson–meson, meson–nucleon atoms and meson–deuteron compounds. Finally, we compare the quantum field theory framework used here with the traditional approach, which is based on quantum-mechanical potential scattering.

Scalar mesons moving in a finite volume and the role of partial wave mixing

Using effective field theory methods, we discuss the extraction of the mass and width of the scalar mesons f0(980) and a0(980) from the finite-volume spectrum in lattice QCD. In particular, it is argued that the nature of these states can be studied by invoking twisted boundary conditions, as well as investigating the quark mass dependence of the spectrum.