Thursday, 2 May 2013

Brookhaven Forum Live Blog IV

First Parallel session.  Conference website

Abhishek Kumar, Searching for Very Light Stops
  • Stops relevant for naturalness, take the case m_stop < m_top.
  • Non-standard stop decays: b-W-neutralino with W on/off shell, c-neutralino.
  • Use MFV to handle the flavour-violating decays.
  • Flavour-violating decay can dominate over four-body decay, even when both are allowed.  Depends on left/right handed nature of lightest stop.
  • ISR needed to account for MET properly.
  • Limits up to ~250 GeV.
Sujeet Akula, Gluino-driven Radiative Breaking in Grand Unified Supergravity
  • Pointed towards Higgs to two photons, among other things, as evidence for light sleptons
  • Of course, also lots of things that push SUSY scale up.
  • Good talk, but too long on the background.  Get to what's new before you run out of time!
  • Basic structure: gluino mass at GUT scale is much larger than the other soft masses.
  • Heavy gluino drives squarks heavy and radiatively breaks EWSB.
  • Higgsino mass mu also driven large.
  • Large seems to mean a factor of 10.
  • Non-universal gaugino masses need non-trivial GUT-scale Higgses.
This is claiming a lot for only tweaking the CMSSM by one number.

Eva Popenda, Squark Pair Production at NLO matched with Parton Showers
  • NLO standard is Prospino, which assumes that all squarks degenerate.
  • Go beyond that for the first time in an event generator.
  • This is all a bit technical for me.
  • Even when squarks degenerate, subchannel cross sections disagree: Prospino assumption (all subchannels identical) not exact.
  • NLO corrections can give ~20% corrections to shapes of distributions.

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