Speaker
Juri Fiaschi
(University of Southampton)
Description
We explore the effects of Photon Induced (PI) production of a dilepton final state in the Large
Hadron Collider environment. Using QED Parton Distribution Function (PDF) sets we can treat
the photons as real partons inside the protons and compare their yield directly to that of the Drell-
Yan (DY) process. In particular, we concentrate on an error analysis of the two mechanisms. In
order to do so, we use the NNPDF set, which comes with a set of replicas to estimate the systematic
PDF error. On the one hand, we find that the PI contribution becomes dominant over DY above
a dilepton invariant mass of 3 TeV. On the other hand, the PI predictions are affected by a large
error coming from the QED PDFs, well above the one affecting the DY mode. We assess the
impact of these uncertainties in the context of resonant and non-resonant searches for a neutral
massive vector boson (Z') through the differential cross section and Forward-Backward Asymmetry
(AFB) observables as a function of the dilepton invariant mass. While the former is subject to the
aforementioned significant residual errors the latter shows the systematic error cancellation expected
(recall that AFB is a ratio of cross sections) even in presence of PI contributions, so that the recently
emphasized key role played by AFB as a valid tool for both Z' discovery and interpretation in both
resonant and non-resonant mode is further consolidated."
Primary author
Juri Fiaschi
(University of Southampton)
