Wednesday, 28 May 2014

Planck 2014 Liveblog: Day Two Session 4

Final session of the day, I'm in the flavour and neutrinos section.

4:40 pm: Origin of Radiative Neutrino Masses and its Collider Phenomenology, Yi Cai

The see-saw mechanism can be understood as opening up of the effective Weinberg operator.  Types I/II/III correspond to different ways of doing this.  Of course, these models are pretty much untestable.

Radiative models can be thought of as different ways of opening up higher dimension operators (dim-7, 9 etc).

Angelic model based on dim-9 operator.  Involves two lepto-quark scalars and a gluino-like fermion. Neutrino masses proportional to bottom mass, and one neutrino very light.

Model then has constraints from flavour, e.g. μ to eγ or eee.  Despite these, can hope to look for signals from relatively light (TeV) leptoquark/fermion octet; limits weak as avoid most searches so far.

5:00 pm: Neutrino Masses and Conformal Symmetry, Juri Smirnov

Conformal theory generating Higgs masses from CW potential.  Needs hidden sector with bosonic degrees of freedom.  Hidden sector TeV-scale VEV.

I don't see how this leads in to the neutrino mass models discussed, which just seem to be some generic model with TeV-scale scalar vevs and neutrino Yukawas comparable to those of the charged fermions.

5:20 pm: Precision tests of unitarity in leptonic mixing, Lorenzo Basso

The SM as known is complete; we can not make further predictions within it, only do consistency checks.  Some anomalies exist.  Example, Z invisible width suppressed by two sigma to SM prediction.  Possible if Z-νν coupling suppression (and similarly for charged currents), perhaps by sterile neutrinos.  These will lead to the effective PMNS matrix for the active neutrinos being non-unitary.

EWFit: Note that Higgs mass makes W mass fit slightly worse.

Looking for 0.001 effect, so need data of comparable accuracy.  Only about 10.

Removing a data point from fit; why?

5:40 pm: Triplet extended MSSM: Fine Tuning vs Perturbativity & Experiment, Stefano Di Chiara

I've decided to change session for the last talk.

TESSM has two terms in W in addition to MSSM.  Large triplet-Hu-Hd coupling should improve fine tuning.  Parameter scan including negative parameters not usually considered.

Theory runs non-perturbative by GUT scale for large λ, but okay to lower scale, say flavour scale.

Find that triplet can suppress as well as enhance Higgs to diphotons.  Comes when triplet coupling or Wino mass negative.

For now, no additional constraints from Higgs couplings.

Model is slightly disfavoured compared to MSSM due to b to s gamma.

No comments:

Post a Comment