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Collider Cross Talk
Brendon Bullard, Eleni Vryonidou,"Higgs top coupling and CP measurement in the Higgs top sector" [ATLAS, THEORY]
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Europe/Zurich
4/2-011 - TH common room (CERN)
Description
Abstract:
The talk will describe recent progress on searching for new sources of CP violation in the top-Higgs coupling. The focus will be on constraining CP mixing through tree-level associated production of the Higgs boson with one or two top quarks, studied through effective field theory operators. A theoretical overview will cover constraining power from the construction of CP-odd observables in the associated top-Higgs production modes [arxiv:2412.10309]. Additional sensitivity derived through the loop-level gluon-fusion production process will also be discussed.
A recent result from ATLAS [arxiv:2606.04855] comprehensively studies the top-Higgs coupling by simultaneously measuring ttH and tH production rates in the diphoton final state. The measurement is performed using 164 fb$^{-1}$ from Run 3, and is combined with the previous Run 2 analysis to constrain the top Yukawa coupling and its CP mixing angle, rejecting the CP-odd scenario with a significance of over 5 sigma. The measurement provides the most stringent direct constraints on the CP structure of the top-Higgs Yukawa interaction to date.
Brendon Bullard:
Brendon Bullard is a research associate at SLAC and is a member of the ATLAS collaboration. His physics interests are focused on understanding the role of the Higgs boson in early universe cosmology through measurements of the Higgs self-coupling and top quark Yukawa coupling. He obtained his PhD at Harvard University in 2022 with the first differential cross section measurement of ttW production. He leads development of machine learning models for b-jet reconstruction and contributes to construction of the innermost layers of the ATLAS ITk pixel detector upgrade at SLAC.
Eleni Vryonidou:
Eleni Vryonidou is an Assistant Professor working in collider phenomenology at the University of Cyprus. Before joining the University of Cyprus she held an academic position at the University of Manchester. Her work focuses on Effective Field Theory. In particular she has worked extensively on higher-order computations and global interpretations of data within the EFT framework. She is also interested in CP-violation and in how this can be probed at colliders through CP-sensitive observables in the Higgs and top sectors.