Speaker
Description
The Lüscher scattering formalism is a popular method which allows the extraction of two-to-two scattering amplitudes from the finite-volume spectrum. Recent lattice calculations have highlighted the limitations of the formalism in systems in which a lighter particle can be exchanged between the two scatterers (e.g. $NN$ or $DD^*$ scattering). This leads to the presence of a left-hand cut just below the two-particle threshold in the partial-wave-projected amplitudes, on which the sub-threshold analytic continuation of the standard method breaks down. In this talk, we review our proposed extension of the formalism to the left-hand cut and give an update on formal developments, including the extension to non-identical scatterers (applicable to $DD^*$ and similar processes) and some limiting cases. We present also some developments in solving the integral equations used to retrieve scattering amplitudes from intermediary K-matrices, making contact with the three-particle RFT formalism.
