Name: LHC EFT WG meeting
Start: 2025-03-03T16:00:00+01:00
End: 2025-03-03T17:30:00+01:00
Location: No location set

- 1
  
  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