LHC EFT WG meeting

Monday 3 Mar 2025, 16:00 → 17:30 Europe/Zurich

Karolos Potamianos (University of Warwick (GB))

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16:00 → 16:30 Dimension-8 operators in W+W− production via gluon fusion

We investigate the impact of dimension-8 operators on W+W− production at the LHC for the incoming gluon-gluon channel. To this end, we have identified all dimension-8 CP-even operators contributing to the process in question, and computed the corresponding tree-level helicity amplitudes for fully-leptonic decays of the W bosons. These are implemented in the program MCFM-RE, which automatically incorporates the effect of a jet-veto to reduce the otherwise overwhelming tt¯ background. We find that, unless we break the hierarchy of the effective field theory (EFT), the interference of the dimension-8 operators with the Standard Model is negligible across the considered distributions. This justifies including the square of dimension-6 operators when performing EFT fits with this channel. We then present new constraints on CP-even and CP-odd dimension-6 operators within the EFT regime. Lastly, we postulate a scenario in which the hierarchy of the EFT is broken, justified by the strong constraints on dimension-6 operators from existing on-shell Higgs data. In this scenario, we discuss the constraints that can be reasonably set on CP-even dimension-8 operators with current and future data. We remark that the effect of the jet-veto on the ability to constrain new physics in the W+W− channel is quite dramatic and must be properly taken into account.

Speaker: Daniel James Gillies

2025-03-03-LHCEFTWG-Recording.mp4

arXiv:2412.16020

LHC EFT Slides.pdf