Electric dipole moment of the neutron from a flavor changing Higgs-boson

Jan Olav Eeg, FI

The existence of an electric dipole moment (EDM) of an elementary particle is a  quantity which violates time reversal (T-) symmetry. Trusting the CPT-symmetry valid in all local quantum field theories, EDMs are also CP-violating quantities. Therefore studies of EDMs give important information on the matter anti-matter asymmetry in the universe. Within the Standard Model (SM) of particle physics, EDMs are small and given by (higher) loop effects and through the Cabibbi-Kobayashi-Maskawa (CKM) CP-violating phase. Experimentally  only bounds on electron, muon, proton and neutron EDMs are  determined. Theories beyond the SM typically contain more sources of CP-violation than the SM. Therefore calculations of EDMs within such theories will put bounds on the parameters of such  (hypothetical) theories. [continued below]  

(The slides will be available here)

(cont.) The properties of the Higgs-boson is still not very well established.
Recently, some authors have assumed  the excistence of a
flavor changing (FC) Higgs-couplings to fermions. The consequences of this
hypothesis have been explored for B-\bar{B} mixing for some couplings
(b --> d transitions). The EDM of the neutron is considered to one loop
level only.

In the present study I extend the analysis to the two loop level. Some of
the contributions turn out to be logarithmically divergent, showing that a
theory based on the considered FC coupling alone is non-renormalizable.
I parametrize the divergence in terms of a cut-off scale $\Lambda$, being
thought of as the scale where presently unknown New Physics might occurr.

I find a bound on the EDM of the neutron of the same order of magnitude as
found by previous authors. If I assume that the bound obtained by previous
authors is saturated, I find that  the calculated EDM of the neutron might
be just below the experimental bound.


Weekly Theory Seminar. Note the time!

Published Jan. 19, 2017 3:17 PM - Last modified Jan. 19, 2017 3:17 PM