Wednesday, 27 May 2015

Planck 2015 Liveblog: Day Three Session Two

The second session today is ahead of the curve, with two talks I'm somewhat interested in.  Unfortunately the exception is the middle talk.  We are, of course, almost 30 minutes over time.

11:56 am: "Selected Physics Highlights from ATLAS", John Parsons

We had CMS on Monday.  It would have been stupid to put the two collaborations together.  LHCb is tomorrow.

Run 1 was great, pile up, blah blah blah.  The usual experimentalist black magic.

Standard Model cross section plot.  Add a new column to it for Higgs.  Higgs plots we've all seen many times by now.  Higgs mass still statistics-dominated, at 0.25 GeV uncertainty or so.

Higgs as (new) tool for BSM.  Invisible width; bound of 30% from VBF, looks stronger than I remember.  Resonance decaying to Higgs pairs, small excess at 300 GeV (2.4 σ).  Substructure used to set limits in the high-mass regime, with sub-jet b-tagging.  Exclude RS KK graviton to 900 GeV in this channel.

Searches for additional Higgs bosons.  New results for SM Higgs decaying to light pseudoscalars, looking for muon resonances.  Excluded BR > few % in most interesting, few GeV regime.

SUSY searches.  Degenerate gluino-LSP limit at 600-800 GeV.  Gaps still there in stop constraints, due to different and complex decay modes.  Electroweak gaugino production, limits in non-degenerate regime up to 700 GeV.

Interesting excess in lljj + MET search.  I've seen a number of papers interpreting this as leptoquarks, but I shouldn't be surprised to see this as SUSY.  Excess is mostly in electron channel; some excess in muon but less significant and spectrum not as suggestive.

Non-standard searches.  Nonpointing/delayed photons, e.g. from delayed NLSP decay to gravitino (among other channels).  Relies on fine segmentation of EM calorimeter, plus timing resolution; remember absurd pileup problem.  Calibrate with beam spread (distance), W/Z decays (timing).  No excess seen.  A lot of searches of this kind have apparently been done.

Dark Matter mono-X searches.  Still based on EFT, but with momentum transfer truncation to avoid breakdown of EFT validity.  Theoretical uncertainty introduced in this way.  Push towards benchmark mediator models to avoid this, joint ATLAS-CMS effort.

Lepton jets.  Develop specialised reconstruction algorithms.  Candidate events observed, but no excess over expected background.  Also search for displaced LJs.

Various non-SUSY searches.  These all look standard.  T, B limits at 600-800 GeV.  Search for diboson resonance (WW or similar).  3-ish σ excess at 2 TeV.  tt resonances, actually stronger for broader resonances.

The future: Run 2 to start in just a few days at 13 TeV, run for three years before second long shutdown.  Run 3 cover 2020 to 2022, reach 300 ifb.  Run 2 has new layer of silicon pixel detector.

What assumptions in EW gaugino production case? Work is in simplified model (obviously).  Does not rule out g-2 in (at least) pMSSM.
Official combination of h to γγ with CMS?  No, and now more focused on Run 2.
Limits on Sphaleron-induced processes?  Limits on high-mulitplicity from BH searches, but it would need to be reinterpreted.

12:30 pm: "Radiative Corrections in non-Supersymmetric Heterotic Vacua", Carlo Angelantonj 

This talk I'm not really interesting in.

1:05 pm: "Holography and Localisation of Gravity", Costas Bachas

 Okay, this is about exact solutions of type-IIB supergravity.  This is not as interesting as I thought it would be.

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