Light quark mass dependence of the X(3872) in XEFT

Understand

The quark mass dependence of hadrons is an important input for lattice calculations.

• We investigate the light quark mass dependence of the binding energy of the X(3872) and the Dbar0-D*0 scattering length in the C=+1 channel to next-to-leading order in XEFT where pion interactions are perturbative.
• At this order, the quark mass dependence is determined by a quark mass-dependent contact interaction in addition to the one-pion exchange.
• Using naturalness arguments to constrain unknown parameters, we find a moderate sensitivity of the binding energy for quark masses up to twice the physical value while the scattering length is more sensitive.