Rethinking the X(3872)

TL;DR

This paper reexamines the quantum number assignment of the X(3872), exploring various interpretations including charmonium and tetraquark models, and discusses implications for its production, mass, and partner states.

Contribution

It provides a comprehensive analysis of the X(3872)'s quantum numbers and explores different theoretical models to explain its properties and spectrum.

Findings

BaBar analysis favors 2-+ quantum numbers for X(3872)

The 1D2 charmonium interpretation faces challenges from production cross section and mass predictions

Tetraquark models predict a rich spectrum of partner states

Abstract

The BaBar analysis which favours $2^{-+}$ quantum numbers for the X(3872) implies that it may be none other than the 1D2 charmonia state. In that case the isospin breaking in closed flavour modes may be the result of re-scattering from open flavour. However, the observed production cross section in proton-antiproton collisions is much larger than expectations, while the mass of the state, compared to the predictions of a string model, is too high. The 1D2 assignment would imply a 3D2 partner nearby in mass, which may be the X(3875). In the tetraquark interpretation the $2^{-+}$ assignment implies a rich spectrum of partner states, although the X(3872) may be among the few which are narrow enough to be observable. This talk is based in part on "The 2-+ assignment for the X(3872)" by T. J. Burns, F. Piccinini, A. D. Polosa & C. Sabelli (Phys. Rev. D 82, 074003 (2010); arXiv:1008.0018 [hep-ph]).