From t.e.j.underwood@durham.ac.uk Wed May 16 06:01:58 2007
Date: Wed, 16 May 2007 10:53:50 +0100
From: Tom Underwood <t.e.j.underwood@durham.ac.uk>
To: logan@physics.carleton.ca, timb@slac.stanford.edu, heinemey@mail.cern.ch, rasp@mppmu.mpg.de, gaoyn@mail.tsinghua.edu.cn, yasuhiro.okada@kek.jp, MBattaglia@lbl.gov, zhangzq@lal.in2p3.fr, okadan@post.kek.jp
Subject: Possible contribution to the LCWS 2007 programme

Dear Conveners,

Is it too late to be considered for a contribution to the LCWS 2007?

If possible, I would like to speak in one of either the Higgs or the
Cosmological Connections sessions.

The title of my talk would be:
"Dirac neutrinos, Baryogenesis and a Vanishing Higgs in a Minimal
Extension of the Standard Model"

Abstract:
We consider a minimal, lepton number conserving extension to the
Standard Model providing Dirac neutrinos without resorting to tiny
Yukawa couplings. Small neutrino masses arise because the model contains
a spontaneously broken global U(1) symmetry in its gauge singlet (or
`phantom') sector - this suppresses neutrino masses via a
Froggatt-Nielsen type mechanism. We show that successful baryogenesis
through leptogenesis is possible in this case and that this suggests an
electroweak scale VEV for the gauge singlet scalar. The model contains
two physical Higgs bosons and a massless Goldstone boson. The existence
of the Goldstone boson suppresses the Higgs to bb(bar) branching ratio
and for a plausible range of Higgs masses one or both Higgs bosons will
decay mainly into invisible Goldstone boson pairs. We consider the
implications of this scenario for Higgs discovery at colliders.

Thanks for your consideration.

Best regards,
Tom Underwood