Speaker
Description
We consider three-flavor QCD and perform a determination of the low energy coupling $\hat g$ of SU(2) Heavy Meson Chiral Perturbation Theory. It is the $B^*B\pi$ coupling in the limit of static heavy and chiral light quarks in $N_\mathrm{f}=2+1$ flavor QCD and has not been determined with precision thus far. The calculation is performed on the $2+1$ flavor CLS ensembles using the summed GEVP method.
The extrapolation to the limit of chiral light quarks is based on a number of gauge ensembles with pion masses in the range from $420\,$MeV down to $130\,$MeV. This allows us to significantly reduce the systematic uncertainty from the extrapolation compared to previous works. Only a weak dependence on the lattice spacing is visible in our results.
This work is a first step in the $2+1$ flavor HQET program of the ALPHA collaboration.
