Monday, 25 May 2015

Planck 2015 Liveblog: Day One, Session One

So Planck starts today, with a day full of plenary talks.  It looks like a fairly technical slate, too, but on the other hand I got a good night's sleep last night so I might be able to stay awake.  I could do with another cup of coffee, but that's always true.

The internet here is terrible, so this won't be a true liveblog.  I'll save my updates for the end of each session, because otherwise this just isn't going to work.

09:30 am: "Prospects for Higgs and Supersymmetry at LHC Run 2 and Beyond", John Ellis

We start with John Ellis telling us why SUSY is still true.  I see he's still using the opening slide with the footsteps in the desert.  Though using The World is Not Enough is new.  Seven reasons for new physics:
  • Instability of Higgs vacuum
  • Dark Matter
  • Baryon Asymmetry
  • Neutrino masses
  • Hierarchy Problem
  • Inflation
  • Quantum gravity
One, four and five here are debatable.

Another claim that Run 1 is evidence for SUSY.  Indeed, claimed three new reasons, of which only the stability of the Higgs vacuum is truly evidence (other two arguments very much compatible with SM, to say nothing of non-SUSY models).  Dominant contribution to Higgs instability comes from top Yukawa (no surprise there).  Instability scale is 1010 to 1012 GeV.  Argues that this is a serious problem, in spite of the long decay lifetime, due to inflation.  (I read a recent paper that contests this, I might write a blog post on it later.)

Of course, this problem goes away in composite Higgs models as the Higgs doesn't exist at those scales.

Argument why this needs SUSY: easiest way to stabilise Higgs potential is to add a stop-like scalar.  This works, but now have to worry about all the new quartics; one of them might blow up.  To avoid this, simplest idea is to add Higgsino-like fermions.  But at this point, why are you not doing SUSY?  OK, that's a good argument.

SUSY DM: in MSSM, LSP can be either neutralino or gravitino.  Gravitino LSP understudied?  But having made that point, John decides to focus on neutralino.

Interestingly, John will be talking about pMSSM10.  A couple of years ago in Durham, he seemed less interested in pMSSM approaches.  Also talking about CMSSM.  Muon g-2 comes up as motivation for light SUSY.  Note not possible in CMSSM, but allowed in pMSSM10.

Current best-fit CMSSM: stau-neutralino coannihilation region, ar about 400 GeV.  This could be measured quite well at LHC, suggesting that we have the usual case where SUSY is predicted to be just above the current limits.  Though that doesn't appear to be consistent with some of the plots he's shown.  I should note that the talks are not (yet?) online, which is annoying; I'm used to looking at the slides on my laptop, giving me the chance to check details and ensure I don't miss anything.  There have been a lot of plots that I can't read in this talk.

We finish with a discussion of future colliders, in particular of the FCC-ee (formerly TLEP) proposal.

No, we finish with the parody poster of SUSY 2215.  Did John miss the point of that poster?

What is chi-squared per degree of freedom?  About one in pMSSM, though it's complicated by the Higgs measurements which restrain model without discriminating in parameter space.

10:00 am: "Recent Results with CMS", Niki Saoulidou

The only experimental talk of the day, which tells us what kind of conference this is going to be.  No major results will be announced here, of course.

I can smell coffee, which seems to be nearly an hour early.  I can also hear some less than polite individuals who are talking outside the amphitheatre, which is making it hard for me to follow this talk.

Part One: Standard Model measurements

 Higgs has been found, and it's couplings are all SM-like.  It is spin-0 (presumably compared to spin-2, though I couldn't make out the slide).

Top: mass measured.  Cross section measured.  I have almost nothing to say.

QCD: Cross sections.  αS, measured past 1 TeV (so sensitivity to coloured particles with unusual decays to a similar level).

EW: W/Z cross sections.  V + jets probes pQCD in unexplored region, helps to constrain PDFs.

Part Two: BSM searches

Dark Matter: Mono-X searches.  EFT and simplified models.  Intend to extend with new searches and more use of simplified models in Run 2.

RS Gravitons.  This is the usual experimental model, with SM on the brane so the gravition decays to leptons.  This lets you set good limits but isn't really a theoretically interesting model (you'd expect it to decay to tops instead).

LED: I missed the explanation of what is going on here, and can't read it from the slide.

Quark/Lepton compositeness.

SUSY: "Natural" (light stops).  Looks like they might be filling in the gaps for stop-neutralino degeneracy, but again, I can't see clearly on the plots.

String Resonances? Yes.
Prospects for improving top mass? About 1 GeV with another 30ifb, then smaller improvements at higher luminosities (systematics limited, I guess).

10:30 am: "Deconstructing E0 SCFT to Solve the Orbifold Paradox", Vadim Kaplunovsky

I really have no idea what this talk is going to be about.  This will also be the most challenging of this session's talks to stay awake through.  The noise of people outside the amphitheatre is getting worse.

This is just too much technical string theory for me.

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