Light quark mass dependence in heavy quarkonium physics

Understand

The issue of chiral extrapolations in heavy quarkonium systems is discussed.

• We show that the light quark mass dependence of the properties of heavy quarkonia is not always suppressed.
• For quarkonia close to an open flavor threshold, even a nonanalytic chiral extrapolation is needed.
• Both these nontrivial facts are demonstrated to appear in the decay widths of the hindered M1 transitions between the first radially excited and ground state P-wave charmonia.