Wednesday, 22 May 2013

Planck 2013 Day Three Live Blog

Once again, I've come into the first review talk halfway through, so I won't comment on it.  Well, other than to note that despite having an hour, he still managed to run ten minutes over.  The theme of the morning is flavour, a topic I never find as interesting as I should.  Conference website.

10:00am: Gustavo Branco, "Flavour physics in the Higgs era"

Oh dear.  These slides are hand-written, that's never a good sign.

Quark alignment: even assuming that both quark Yukawa matrices are (approximately) diagonal in the same basis, there is no reason for the diagonal elements to both be ordered the same way.  The absolute ordering of eigenvalues has no meaning, but the relative ordering does.  There are six possible orderings, only one is aligned in this way.

Generation of complex phases (in CKM matrix) from vacuum.  Non-trivial constraint on Higgs VEVs. It is not enough for the VEVs to have irreducible phases, the actual constraint is stronger.  (If Yukawas are real?)  Not possible with simplest two- or three-Higgs doublet models, need larger symmetry group.

Interesting example of 2HDM with tree-level FCNC but all such couplings are controlled by the CKM matrix, and so are under control.  Not nearly enough details here for me to understand the model at any more than the most superficial level.  Controlled by an abelian symmetry; proven that this is the only such example.  Non-abelian symmetries are an open question.

Summary: Will Higgs particles play an important role in flavour?  Gustavo is optimistic, and says yes.  It's an interesting question, actually, that I haven't seen phrased so explicitly.

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