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Collider Cross Talk

Third generation leptoquarks in CMS and ATLAS

by Izaak Neutelings (CERN (CH)), Mahsana Haleem (Julius Max. Universitaet Wuerzburg (DE))

4/2-011 - TH common room (CERN)

4/2-011 - TH common room


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The leptoquarks, originally predicted by the Grand Unification Theories, are interesting candidates for explaining the similarities between lepton and quark families. They are characterised by features such as QCD colour charge, electric charge, non-zero lepton and baryon numbers, and there are 10 possible types of them (excluding the ones that either couple to only right-handed neutrinos, or violate baryon and lepton numbers) whose interactions with lepton and quark satisfy the SM gauge invariance. Several phenomenological models with leptoquark-like states predict lepton flavour violating decays. Some of these states are also proposed as potential explanations for the anomalies in the B physics, particularly in the semileptonic decays of the B mesons into D or D*, which regained interest in the direct searches for the leptoquarks preferentially coupled to the third-generation fermions. The ATLAS and CMS experiments have looked for the leptoquarks at the LHC in the single, pair, and non-resonant productions using full Run-2 datasets. We will discuss some of the interesting results focusing on the leptoquark coupled with a b quark and a 𝜏 lepton, and will highlight potential improvements for future analyses.

Mahsana Haleem is an experimental particle physicist working on the ATLAS experiment. She earned her PhD from Kansas State University, USA, measuring the associated production of charm quark with W boson. She held postdoc positions at the University of Texas at Dallas, USA, and DESY, Germany. Currently, she is a postdoc researcher at Julius-Maximilian University of Würzburg, Germany. Her primary interest revolves around the Top quark physics and Exotics physics searches. She worked on the searches for the dark photons in prompt, boosted, and collimated leptons topologies using 2011-2012 ATLAS data, and on measuring the differential cross sections of top-quark pairs in association with additional (b)-jets using 2015-2018 data. Recently, she worked on the leptoquark search analyses involving top quark or 𝜏-lepton final states and has been co-leading the leptoquark search groups in Run-2.

Izaak Neutelings earned his Master's and PhD degrees at the University of Zurich (UZH) working on searches for new physics at the CMS experiment, exploiting final states with 𝜏 leptons and bottom quarks. During his PhD, he worked on third-generation leptoquarks in the (b)(b)𝜏𝜏 final state, targeting pair, single and nonresonant production. He has also contributed to the Tau Object Group in CMS, where he worked on the calibration of the reconstruction & identification algorithms of hadronically decayed 𝜏 leptons, helped develop common analysis tools, and was convener of the Tau ID group. He now works as a research fellow at CERN, where he continues work on ditau+jets final states in CMS, including third-generation leptoquarks and the measurement of the anomalous magnetic moment (g – 2) of 𝜏-leptons.