Speaker
Description
In this talk I will discuss differential theoretical predictions for Higgs-boson production in weak-boson fusion and its subsequent decay $H\to b\bar{b}$.
The distinct kinematics of weak-boson fusion allow us to suppress QCD backgrounds by imposing appropriate event selection criteria. However, it was recently observed that in fixed-order calculations these strict event selection criteria lead to large corrections - ~ -40% at NNLO in comparison to LO - with an apparent lack of perturbative convergence. One prominent source of such large effects is the tendency of the QCD radiation in the $H\to b\bar{b}$ decay to reduce the transverse momentum of b-jets to the point where they no longer pass the b-jet selection criteria.
I will show that these large kinematic effects are caused primarily by soft and collinear QCD radiation in the $H\to b\bar{b}$ decay subprocess and that they can be accounted for by using a parton shower. I will present NNLO-accurate predictions for the combined process $pp\to H(\to b\bar{b})jj$, where the $H\to b\bar{b}$ decay subprocess is matched to the Pythia parton shower using the MiNLO method. In comparison with purely fixed-order calculations the consistency of theoretical predictions is dramatically improved. The remaining theoretical uncertainty is of order 5-7%, primarily due to modelling of the differential $H\to b\bar{b}$ distributions.
