Lecture: EW Splitting Functions and High Energy Showering

Speaker:  Dr. Junmou Chen, University of Pittsburgh

Time & Date: 16:00 26th Dec. 2017

Address: Room 208 in the School of Physics

Titel: EW Splitting Functions and High EnergyShowering

Abstract: We  derive the electroweak (EW) collinearsplitting functions up to single  logs. We first derive the splitting functionsin the unbroken limit,  and  then we systematically incorporate effects ofEW symmetry breaking  (EWSB), by imposing a particularly convenient gauge choice(dubbed  “Goldstone Equivalence Gauge”) that disentangles the effects ofGoldstone  bosons and gauge fields in the presence of EWSB. As a result, we  areable to derive splitting functions up to leading power corrections in  v/E. Wealso implement a comprehensive, practical EW showering scheme  based on thesesplitting functions using a Sudakov evolution formalism.  The implementation ofEW showering includes novel features such as  “ultra-collinear” splittings,matching between shower and decay, and  mixed-state evolution of neutral bosons(γ/Z/h) using density-matrices,  kinematic back-reaction corrections inmulti-stage showers. We  demonstrate those new phenomena and features at O(1–10TeV) energies with  some examples.