Next-to-leading ultrasoft running of the heavy quarkonium potentials and spectrum: Spin-independent case

Understand

We compute the next-to-leading logarithmic (NLL) ultrasoft running of the spin-independent singlet potentials up to ${\cal O}(1/m^2)$, and the corresponding contribution to the spectrum.

• This includes the static energy at next-to-next-to-next-to-leading logarithmic (NNNLL) order.
• As a byproduct of these results one could obtain the heavy quarkonium spectrum with N$^3$LL accuracy for $l\not=0$ (angular momentum) and $s=0$ (spin) states, setting the stage for the full analytic and numerical N$^3$LL analysis of such quantity.
• We also compute the next-to-next-to-next-to-next-to-leading order (N$^4$LO) ultrasoft spin-independent contribution to the heavy quarkonium mass and static energy.