Based on Phys.Rev.Lett. 109 (2012) 092001 (arXiv:1203.3898) by Ilya Feige, Matthew D. Schwartz, Iain Stewart and Jesse Thaler

In this paper we computed the distribution of the ratio tau2/tau1 (n-subjettiness variables) for boosted W bosons at the NNNLL level. Our result agrees with Pythia where it is supposed to.

This paper also proposed a way that pileup and underlying event could be corrected for on an event-by-event basis. This plot shows how the n-subjettiness distribution (red) is affected by initial state radiation and the underlying event (purple curve), and how our method can correct back (blue curve) to something which looks close to the original.