Mrinal Dasgupta (Manchester)

We discuss QCD calculations for specific analytic ingredients necessary to construct high logarithmic accuracy (NNLL) parton showers.

In particular we show how to extend the notion of a physical coupling defined in the soft limit into the collinear region. This extension allows for the incorporation of the resummation coefficient known as B2 into a parton shower in an observable independent manner.

Combined with other key developments we mention, our results allow parton showers to achieve NNLL accuracy for a wide class of observables.