Approaching robust EFT limits for CP violation in the Higgs sector

Englert, C. , Galler, P. , Pilkington, A. and Spannowsky, M. (2019) Approaching robust EFT limits for CP violation in the Higgs sector. Physical Review D, 99(9), 095007. (doi: 10.1103/PhysRevD.99.095007)

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Constraining CP-violating interactions in effective field theory (EFT) of dimension six faces two challenges. Firstly, degeneracies in the multi-dimensional space of Wilson coefficients have to be lifted. Secondly, quadratic contributions of CP-odd dimension six operators are difficult to disentangle from squared contributions of CP-even dimension six operators and from linear contributions of dimension eight operators. Both of these problems are present when new sources of CP-violation are present in the interactions between the Higgs boson and heavy strongly-interacting fermions. We show that degeneracies in the Wilson coefficients can be removed by combining measurements of Higgs-plus-two-jet production via gluon fusion with measurements of top-pair associated Higgs production. In addition, we demonstrate that the sensitivity of the analysis can be improved by exploiting the top-quark threshold in the gluon fusion process. Finally, we substantiate a perturbative argument about the validity of EFT by comparing the quadratic and linear contributions from CP-odd dimension six operators and use this to show explicitly that high statistics measurements at future colliders enable the extraction of perturbatively robust constraints on the associated Wilson coefficients.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Galler, Dr Peter and Englert, Professor Christoph
Authors: Englert, C., Galler, P., Pilkington, A., and Spannowsky, M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review D
Publisher:American Physical Society
ISSN (Online):2470-0029
Published Online:13 May 2019
Copyright Holders:Copyright © 2019 American Physical Society
First Published:First published in Physical Review D 99(9): 095007
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
729782Phenomenology from Lattice QCD and Collider PhysicsChristine DaviesScience & Technology Facilities Council (STFC)ST/P000746/1S&E P&A - PHYSICS & ASTRONOMY