Tuesday, 26 May 2015

Planck 2015 Liveblog: Day Two Session Three

The first session after lunch looks pretty dull too.  Also, we are already starting five minutes later.

3:00 pm: "Yukawas in F-theory GUT", Francesco Marchesno

This was supposed to be a talk on inflation, which might have been a little bit interesting.  Instead we have yet another string theory talk.  My tolerance for this is completely topped out, so I'll be doing something else.

3:30 pm: "Gravitational Waves in Double Hybrid Inflation", G Lazarides

A Word talk.  Wow.

SUSY inflation is best, despite giving predictions in conflict with data.

4:00 pm: "Standard Model Inflation & Beyond", Q Shafi

I'm skipping this talk, on the grounds that I should have skipped the prior two.

4:30 pm: "Gauge-Higgs Grand Unification", Y Hosotani

One final effort, to get something out of a talk this afternoon.   Of course, I came in at 4:35 but the session is running 15 minutes late.

Gauge-Higgs unification is, of course, 5D theory where fifth component of extra-dimensional vector field is identified with Higgs.  More specifically, if fifth dimension is not simply connected, there exists an irremovable AB phase that can be related to the Higgs VEV.

Some discussion of model details in RS.  SO(5) x U(1) bulk gauge group.  Gauge potential is not directly observable, so needs only be identified under orbifolding up to gauge transformation.  This is essence of boundary conditions that break the bulk gauge group.

In GHU, Higgs mass is quantum-generated and finite independent of cut-off.  The vacuum instability problem goes away.  It is also consistent with LHC data for AB phase smaller than 0.1.

Predictions: KKZ mass depends only on AB phase.  Constraint mentioned above means larger than 4 TeV.  Despite high mass, muon pair resonance should be visible.  Higgs cubic deflected smaller than SM, though not an LHC measurement.  DM is dark sector fermion; upper bound of 3 TeV in mass.

Above is based on unification of Higgs and EW gauge sector.  Include colour for GUT.  Based on SO(11) bulk, breaking to SO(10) in UV and SO(4) x SO(6) in IR.  Prediction for s2W = 3/8.  Fermions fit in bulk 32, which breaks to 16 + 16bar, and gives only SM content as zero modes.

Higgs arises in same way.  Pure gauge theory already breaks itself, but Higgs is absolutely stable.  Fermions and brane interactions needed to allow Higgs to decay.

Proton decay does not happen ... not entirely clear why.  Apparently, fermion implementation not fully constructed yet, which rather makes me doubt that claim.  Okay, admits that probably will occur but expected sufficiently suppressed.

Why work in RS and not UED?  Need RS to get dynamic EWSB.  Also, problems with W/Z wavefunctions.
Any B/L violation? Violate L with Majorana mass.
Can brane scalars stabilise ED, or need extra GW sector? Need extra sector.
Any string theory realisation?  Unknown.

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