The Effects of Charged Charm Mesons on the Line Shapes of the X(3872)

TL;DR

This paper investigates how charged charm mesons influence the line shapes of the X(3872) resonance, providing a detailed theoretical framework to distinguish between molecular and virtual state interpretations.

Contribution

It introduces a comprehensive calculation of X(3872) line shapes considering charged and neutral charm meson channels and their impact on experimental observables.

Findings

Charged meson channels significantly affect the X(3872) line shapes.

Line shapes vary with decay channels and production modes.

Theoretical corrections to previous models are identified.

Abstract

The quantum numbers J^PC = 1++ of the X(3872) and the proximity of its mass to the D*0 anti-D0 threshold imply that it is either a loosely-bound hadronic molecule whose constituents are a superposition of D*0 anti-D0 and D0 anti-D*0 or it is a virtual state of charm mesons. The line shapes of the X(3872) can discriminate between these two possibilities. At energies within a few MeV of the D*0 anti-D0 threshold, the lines shapes of the X produced in B -> K transitions are determined by its binding energy and its width. Their normalizations are determined by a short-distance constant that is different for B+ -> K+ and B0 -> K0. At energies comparable to the 8 MeV splitting between the D*0 anti-D0 and D*+ D- thresholds, the charged meson channels D*+ D- and D+ D*- have a significant effect on the line shapes of the X. We calculate the line shapes taking into account the resonant coupling between the charged and neutral 1++ channels. The line shapes and their normalizations depend on one additional scattering parameter and two additional short-distance constants associated with the B -> K transitions. The line shapes of the X resonance depend on its decay channel; they are different for J/psi pi+ pi-, J/psi pi+ pi- pi0, and D0 anti-D0 pi0. The line shapes are also different for X produced in B+ decays and in B0 decays. Some conceptual errors in previous work on this problem are pointed out.