Herwiri 1.031: A New Approach to Parton Shower MCs in Precision QCD for the LHC

by Bennie Ward

Thursday 21 Jul 2011, 11:30 → 12:30 Europe/Zurich

4/2-011 - TH common room (CERN)

In this presentation, I will discuss a new approach to the MC event generator realization of parton showers for precision QCD applications such as the physics of the LHC. I will give the essentials of the physical motivation for the approach, which is based on the new IR-improved DGLAP-CS theory, and show how it is now realized in the Herwig 6.5 environment in the new MC event generator Herwiri 1.031, which has then a seamless interface to the MC@NLO framework of Frixione and Webber. The IR-improvement means that, in principle, the k_0 cut-off parameters in Herwig 6.5 can be removed. I will show that the application of Herwiri 1.031 to the Z production process at the Tevatron yields for the soft p_T spectrum a better Chi2/d.o.f fit to the data than does the analogous application of Herwig 6.5, both with and without the MC@NLO exact O(alpha_s). I will explain why this is not an accident. I will also comment on the future directions of the attendant project.

Paper http://arxiv.org/abs/1001.1434

Slides NewAPP-Prtn-SH-CCT-7-21-11.pdf