Heather Logan, [HET Seminar], "On radiatively-induced CP violation in the "real" two Higgs doublet model"

Thursday 16 Nov 2023, 11:00 → 13:00 US/Eastern

Small Seminar Room (https://bnl.zoomgov.com/j/16010362754?pwd=Z1l1SS9JUDlyR1hSUHNyaDV1dTZHUT09)

The two Higgs doublet model (2HDM) with natural flavour 
conservation and a real scalar potential (for CP conservation) is a very 
popular phenomenological and experimental benchmark model.  A couple of 
years ago Fontes et al. pointed out that there is no evident reason why 
the CP violation within the CKM matrix should not "leak" into the scalar 
potential through divergent radiative corrections, thereby rendering the 
real 2HDM theoretically inconsistent.  Unexpectedly, however, their direct 
calculation of the most divergent piece of the 3-loop tadpole for the 
pseudoscalar yielded zero.

We consider this issue working in the unbroken phase of the real 2HDM with 
natural flavour conservation.  We identify two necessary ingredients for 
such a radiative leak, and show that they first appear together only at 
6-loop order in the unbroken phase.  Surprisingly though, we are able to 
show through a diagrammatic argument that the most divergent piece of the 
imaginary part of the relevant diagrams also winds up vanishing at 6 
loops.  Along the way we point out through simple symmetry arguments that 
the version of the 2HDM in which natural flavour conservation is 
implemented using a softly-broken U(1) Peccei-Quinn-type symmetry (in 
place of the usual Z_2) is guaranteed to be safe from leaks of CP 
violation.

CPV-2HDM-BNL23.pdf