Threshold Effects and the Line Shape of the X(3872) in Effective Field Theory

Authors :: Schmidt, M.
Jansen, M.
Hammer, H. -W.
Source :: Phys. Rev. D 98, 014032 (2018)
Publication Year :: 2018
Abstract: Latest measurements suggest that the X(3872) mass lies less than 200 keV away from the D0-Dbar0* threshold, reenforcing its interpretation as a loosely-bound mesonic molecule. This observation implies that in processes like D0-Dbar0-pi0 production, threshold effects could disguise the actual pole position of the X(3872). We propose a new effective field theory with D0, Dbar0 and pi0 degrees of freedom for the X(3872), considering Galilean invariance to be an exact symmetry. The D0* enters as a D0-pi0 p-wave resonance, allowing for a comprehensive study of the influence of pion interactions on the X(3872) width. We calculate relations between the mass of the X(3872), its width, and its line shape in D0-Dbar0-pi0 production up to next-to-leading order. Our results provide a tool for the extraction of the X(3872) pole position from the experimental data near threshold.<br />Comment: 31 pages, 14 figures, published version; added some remarks and four references, edited Figure 12, minor typographic corrections