Speaker
Sebastian Jaeger
(University of Sussex (GB))
Summary
The direct CP violation parameter $\varepsilon^\prime$, measured to about 15\%
accuracy and highly sensitive to BSM effects, is on track to become a new precision
observable as progress in lattice QCD is starting to provide the necessary
non-perturbative operator matrix elements from first principles, and with increasing
accuracy.
This in turn implies a need for controlling so far subleading uncertainties, including from
higher perturbative orders in the calculation of the short-distance ingredients. I report on
the first NNLO calculation of $\varepsilon^\prime$ and some associated theoretical issues.
