# SUSY10

Aug 23 – 28, 2010
Bonn
Europe/Berlin timezone

## Hidden two-Higgs doublet model

Aug 26, 2010, 5:03 PM
15m
Wolfgang-Paul-HS (Bonn)

Nussallee 12

### Speaker

Dr Johan Rathsman (Uppsala University)

### Description

We present a two-Higgs doublet model where only one of the doublets gets a vacuum expectation value and there is a softly broken Z2 symmetry. In this "hidden doublet model", the CP-even states h and H mix, and therefore they both couple to fermions, whereas the hidden states A0 and H+ only couple to fermions via gauge boson-Higgs loops and thus these couplings are strongly suppressed. Our model shares some features with the inert doublet model of Barbieri, Hall and Rychkov, in that it allows h and/or H to be heavy and still satisfy the electroweak precision tests, but since the Z2 symmetry is softly broken, none of the scalars is stable. The model leads to a very interesting Higgs phenomenology. Apart from the possibility of having a heavy h and/or H and thus improving the naturalness of the Higgs sector, the hidden states A0 and H+ may predominantly decay into four fermions via off-shell gauge and Higgs bosons. On the one hand this means that A0 and/or H+ can be very light, so that they may have been produced at LEP but not detected due to the non-standard decay modes. Another possibility is that one of the CP-even Higgs bosons, h or H, is light but has escaped detection because it decays to A0 A0 or H+ H-, which decay in the four fermion modes already mentioned. We have calculated the decays of the hidden states into four fermions at tree level and to two fermions at at one-loop level and also considered electroweak and other experimental constraints on the parameter space of the model.

### Primary author

Dr Johan Rathsman (Uppsala University)

### Co-authors

Glenn Wouda (Uppsala University) Dr Rikard Enberg (Uppsala University)

 Slides