External Seminar by Neda Darvishi

Thursday 7 Oct 2021, 14:00 → 15:00 Europe/London

Title
Classifying Accidental Symmetries in nHDM and Natural SM alignment Limit

Abstract:
I will discuss classifying accidental symmetries in multi-Higgs
Doublet Models (nHDMs). The potentials of nHDMs contain a large number of
SU(2)_L-preserving accidental symmetries as subgroups of the symplectic
group Sp(2n). To classify these, prime invariants and irreducible
representations in bilinear field space can be used that enable us to
explicitly construct accidentally symmetric nHDM potentials. I will
showcase the classification of the symmetries and present the relationship
between the theoretical parameters of the scalar potential for; (i) the
Two Higgs Doublet Model (2HDM) and (ii) the Three Higgs Doublet Model
(3HDM). In this approach, I will present the maximum number of 13
accidental symmetries for the 2HDM potential and 40 accidental symmetries
for the 3HDM potential. Furthermore, I will present the complete set of
continuous maximal symmetries that the potential of 2HDM and 3HDM should
satisfy for the natural Standard Model (SM) alignment limit. As a result,
no large mass scales or fine-tuning is required for such alignment limit,
which still persists even if these symmetries were broken softly by
bilinear mass terms. In particular, the Maximal Symmetric nHDM (MS-nHDM)
can provide natural SM alignment whereas exhibiting quartic coupling
unification up to the Planck scale. I will show that the MS-nHDM are very
predictive extension of the SM governed only by a few BSM parameters that
they allow to determine the entire Higgs-mass spectrum of the model.

Zoom link:  IPPP Seminars (Thursday at 2 pm UK time)

https://durhamuniversity.zoom.us/j/99420124988?pwd=ZEFLSDB3THJtaWZOTU54R25mT1NuZz09

Meeting ID: 994 2012 4988