Topic: The role of the three-body/left-hand cut onthe pole extraction of the Tcc(3875)

Speaker: Prof. Menglin Du

Coordinates: PCFT C1124, 16:00, Thursday, November 2

Abstract: A coupled-channel approach is applied to the charged tetraquark state Tcc(3875)+ discovered by the LHCb collaboration with special attention paid to the three-body  dynamics when extracting its pole position.  The approach is  extended to the lattice studies with unphysical pion masses.  We discuss recent lattice data for the Tcc(3875)+ state to stress a  potentially strong impact of left-hand cuts from the one-pion  exchange on the pole extraction for near-threshold states. In particular, if the left-hand cut is located close to the two-particle threshold, which happens naturally in the DD∗ system for the pion mass  exceeding its physical value, the effective-range expansion is valid only in the very limited energy range up to the cut and as  such is of little use to reliably extract the poles. Then, an  accurate extraction of the pole locations requires the one-pion  exchange to be implemented explicitly into the scattering amplitudes.