Tuesday, 24 May 2016

Planck 2016 Liveblog: Day Two Session Two

The first of three parallel sessions today, and I've decided on the SUSY 2 session.  Though looking at the talks, there seems to be more of a DM theme with two talks not necessarily being supersymmetric.

11:30 am: Relic density of wino-like dark matter in the MSSM, Pedro Ruiz-Femenia

Study of Sommerfeld effect away from pure wino/Higgsino limits.  Eh.  Some mixing weakens ID constraints.

11:50 am: Blind spots and their impact on neutralino relic abundance in the NMSSM, Pawel Szczerbiak


12:10 pm: Simplified DM models with the full gauge symmetry, Alexander Natale

Prior effective operator studies of DM models at LHC/DD have limitations.  LHC models that do not respect full EW symmetry can lead to spurious contributions from longitudinal polarisations of gauge bosons.  DD must be concerned about running from EW scale to low-energy scattering scale, which will generally mix operators and can lead to important effects.

Simplified models written in full EW phase look to avoid this.  Model involves multiple scalar mediators allowing variable couplings to different chirality/flavour quarks.  DM then excluded by DD unless it is light, < 10 GeV.

12:30 pm: Right-handed sneutrino dark matter in the mSUGRA, Shankha Banerjee

Add right-handed neutrino superfields for neutrino masses.  Take limit where superpotential respects lepton number, so sneutrinos are light and can effect EW scale pheno; right-handed sneutrinos can be LSP.

12:50 pm: The Coannihilation Codex, Anna Kaminska

Complete classification of coannihilating simplified models, within moderate assumptions.  In turn allows a classification of LHC processes searching for coannihilating states, in particular identify unused search strategies.

Assumptions are that DM is usual thermal WIMP, coannihilation involves only 2 to 2 processes, and no new fields with spins larger than 1.  Classification is then a simple matter of enumerating all possible SM quantum numbers.  List consists of finite set of families characterised by free hypercharge and isospin quantum numbers.  Distinct classification of models by s-channel, t-channel and hybrid coannihilation.

At LHC, can pair produce coannihilating partners/mediator states with gauge interactions.  Can also produce states directly through coannihilation couplings, directly probing those processes.  The same diagrams lead to decays of the partner states, giving a general signal.

s-channel models have interesting complementarity between resonance searches for mediators, and production of resonance final states plus MET from decays of coannihilating partners.  Allows complete test of paradigm.

t-channel models more SUSY-like, with compressed spectra and always some MET.

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