The Heavy Quark Spin Symmetry Partners of the X(3872)

TL;DR

This paper predicts new heavy quark spin symmetry partner states of the X(3872) in the charmed meson-antimeson system using effective field theory, suggesting a total of six molecular states with estimated uncertainties.

Contribution

It introduces the prediction of a new $2^{++}$ partner of X(3872) and, assuming X(3915) as a heavy spin symmetry partner, forecasts six molecular states in total.

Findings

Predicted a $2^{++}$ heavy quark spin symmetry partner called X(4012).

Estimated uncertainties from higher order effects and corrections.

Suggested a total of six $D^{(*)}ar{D}^{(*)}$ molecular states.

Abstract

We explore the consequences of heavy quark spin symmetry for the charmed meson-antimeson system in a contact-range (or pionless) effective field theory. As a trivial consequence, we theorize the existence of a heavy quark spin symmetry partner of the X(3872), with $J^{PC}=2^{++}$, which we call X(4012) in reference to its predicted mass. If we additionally assume that the X(3915) is a $0^{++}$ heavy spin symmetry partner of the X(3872), we end up predicting a total of six $D^{(*)}\bar{D}^{(*)}$ molecular states. We also discuss the error induced by higher order effects such as finite heavy quark mass corrections, pion exchanges and coupled channels, allowing us to estimate the expected theoretical uncertainties in the position of these new states.