Speaker: 
Juri Fiaschi
Speaker affiliation: 
University of Southampton
Date: 
Thursday, March 19, 2015 - 13:00
Room: 
Building 46, seminar room (5th floor)
Title: 
Z’ physics: new bounds, searches and the role of AFB as a discovery tool at the LHC
Abstract: 

The role of the Forward-Backward Asymmetry (AFB) in Z physics is commonly
associated to the interpretation of experimental data after a possible
discovery. This observable is indeed used to distinguish between different
models predicting at least one extra heavy spin-1 Z -boson. We examine the role
of AFB in searching for new heavy Z -bosons and show that it might be powerful
at the CERN Large Hadron Collider (LHC). We analyse two different scenarios:
narrow width Z -bosons and wide Z -bosons. We find that, in the first case, the
significance of the AFB search can be comparable with the bump search usually
adopted by the experimental collaborations. The advantage of using AFB would be
minimizing systematical errors, being AFB a ratio of (differential) cross
sections. In the second case, the AFB search can win over the bump search in
terms of event shape. The structure of the AFB distribution as a function of
the invariant mass of the reconstructed Z -boson could nail down the new broad
resonance much better than the event counting strategy usually adopted in such
cases.