19 Jul/24
11:00 - 13:00 (Europe/Zurich)

Production of a pair of τ leptons via photon-photon fusion and probing tau g-2


4/2-011 at CERN

In recent years, photon-photon interactions at the LHC have attracted considerable attention. These interactions extend the verification of the Electro-Weak (EW) sector of the Standard Model (SM) into new domains, either by probing the SM gauge couplings to unprecedented precision or by searching for new physics exclusively coupled to the EW sector. These photons, emitted by colliding protons or ions, can be studied through ultraperipheral collisions characterized by the absence of hadronic activity. The ATLAS and CMS collaborations first observed the production of a pair of tau leptons in photon-photon events in PbPb ultraperipheral collision (UPC) events. Recently, the CMS collaboration observed this process in proton-proton collisions. Photon-photon interactions in proton-proton collisions enable probing of energy scales up to the TeV range and are more sensitive to new physics effects. During the seminar we will discuss how these experimental achievements set the stage for new measurements of this kind and their contribution to the searches for new physics affecting the anomalous electromagnetic dipole moment of tau lepton through the SM Effective Field Theory (SMEFT) approach.

Michael Pitt (CMS) is an experimental physicist working with the CMS collaboration. After obtaining the PhD at the Weizmann Institute of Science, he was selected for the CERN Research Fellow program, where he contributed to searches for BSM physics via photon-photon interactions using the tagged protons with the CMS experiment. Now, he is a postdoctoral researcher at the University of Kansas, continuing to work on photon-photon interactions in pp collisions. Particularly, he worked on the recent CMS measurement of pair production of τ leptons in pp collisions. Michael is the convener of the CMS QCD sub-group and is currently interested in boosting the CMS forward physics program with comprehensive studies of exclusive and diffractive interactions.


Ilaria Brivio (TH) obtained her PhD in 2016 from the Universidad Autonoma in Madrid. She then held postdoctoral positions at the Niels Bohr Institute in Copenhagen and at the University of Heidelberg, before becoming assistant professor at the University of Zurich and at the University of Bologna, where she's currently based. Her research explores phenomenological applications of Effective Field Theories to new physics searches, including studies of Higgs and EW processes at LHC in the context of SMEFT, HEFT and the EFT of axion-like particles. She's a convener of the LHC EFT WG and the main developer of the SMEFTsim UFO model.