1. General Seminars

1) Precision Diboson Observables for the LHC - 2) Photon Jets

by Jakub Scholtz (Harvard Univ)

Aula Seminari (LNF INFN)

Aula Seminari


1) Precision Diboson Observables for the LHC Motivated by the restoration of SU(2)×U(1) at high energy, we suggest that certain ratios of diboson differential cross sections can be used as high-precision observables at the LHC. We rewrite leading-order diboson partonic cross sections in a form that makes their SU(2)×U(1)and custodial SU(2) structure more explicit than in previous literature, and identify important aspects of this structure that survive even in hadronic cross sections. We then focus on higher-order corrections to ratios of γγ, Zγ and ZZ processes, including full next-to-leading-order corrections and gg initial-state contributions, and argue that these ratios can likely be predicted to better than 5%, which should make them useful in searches for new phenomena. The ratio of Zγ to γγ is especially promising in the near term, due to large rates and to exceptional cancellations of QCD-related uncertainties. 2) Photon Jets Photon Jets are beams of collimated photons that may appear as a single (poorly isolated) photon to calorimeters at LHC. Several recent articles suggested that the recent 750 GeV excess at LHC may be explained as pairs of Photon Jets rather than pairs of photons. I will briefly introduce the excess and then proceed to highlight some of the tools that we might find useful to discriminate between photons, neutral pion rich hadronic jets and Photon Jets.