Wednesday, 28 August 2013

SUSY 2013 Live Blog: Day Two Session 4

For the last session of the day I've returned to the SUSY phenomenology parallel talks.

4:30pm: Diego Redigolo, "Phenomenology of general gauge mediation in light of a 125 GeV Higgs"

GGM always has gravitino LSP.  Follows that NLSP has universal decays.  Assuming R-parity, all events at LHC contain either high pT objects plus MET or heavy long-lived particles.  How does this change with the Higgs discovery?

In GGM, A-terms are loop suppressed in the UV.  This causes problems for light SUSY and a 125 GeV Higgs.  Simplest case, large stop scale, means squarks cannot be NLSP.  Gluinos can be but very constrained by jets + MET/R-hadron searches.  Any non-coloured superpartner may still be NLSP.

This set-up is a GGM realisation of the Mini-Split scenario.

A possible extension of GGM involves couplings of Higgs to hidden sector.  This raises the Higgs soft masses over the slepton masses, which in GGM are equal.  This can make selectron/smuon NLSP possible, by modifying the Yukawa contribution to the running.

Comparison to slepton co-NLSP case; signal of two leptons plus MET, with limits of 200-300 GeV on the sleptons.  With staus heavier than the the other sleptons, when it is produced it can decay to the lighter sleptons.  Our signal now has more leptons; four leptons plus two taus.  (Again, compare to staus lightest; get two leptons plus four taus.)  Limits in progress; nicer signal but lack of optimised searches.

4:50pm: Farvah Nazila Mahmoudi, "Status of MSSM after the LHC 8 TeV run"

Two important points in interpreting SUSY limits from LHC.  First, most limits given in terms of simplified models that do not represent all SUSY possibilities.  Second lower limits are not conclusive.  Ultimately must combine sectors to draw conclusions.

pMSSM is the framework here, which is the obvious choice given the first comment above.  This particular project uses 200 million model points in general analyses, over one billion(!) in dedicated analyses.

Squarks and gluinos below a TeV still survive.

Now consider interplay with other sectors.  Higgs mass is obviously constraining, but pMSSM has enough space to get by.  Searches for other Higgs, esp. pseudoscalar, can be important.  Data points to decoupling regime even within the pMSSM.

5:10pm: Sho Iwamoto, "Muon g-2 vs LHC in supersymmetric models"

MSSM can solve the muon g-2 anomaly, which is another albeit less-common motivation.  Can we use it to motivate the SUSY spectrum?  What then can we say about the LHC searches?

We need light sleptons and charginos.  We push the squarks heavy to avoid limits.  We also put make the staus heavy for convenience and impose unified gaugino mass relations.  This leads to a TeV gluino  with uncoloured superpartners lighter than that.  We can also reduce the parameter space to four; two slepton masses, one gaugino mass (M2 is obvious choice) and ยต parameter.

LHC searches do cut into parameter space.  However, 1-sigma region still allowed for Wino ~ 400 GeV, slepton ~ 600 GeV.  Entire parameter space can be probed by LHC if we impose the gaugino mass relations (gluino limits) but without them there will be gaps in the excluded regions.

5:30pm: Alexander Morena Briceno, "CP-violation in top quark pair production at hadron colliders in the complex MFV-MSSM"

Complex MFV: complex phases come from soft parameters.

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