SUSY naturalness without prejudice

Who: Dumitru Ghilencea (CERN & NIPNE Bucharest)
When: Monday, November 25, 2013 at 14:15
Where: U49

Unlike the Standard Model, supersymmetric models stabilize the EW scale v and predict that it is function of the SUSY UV parameters (p_i). I provide a comparative study of the EW fine tuning Delta (measuring this stability) in the most popular SUSY models consistent with recent LHC results for the Higgs sector. I show that if one insists on fixing the EW scale v=v(p_i) to its numerical value, the likelihood to fit the EW data is suppressed by Delta (under some assumptions). From this, the condition of a good fit provides an estimate of a model-independent bound for the EW scale fine-tuning: Delta<<exp(d.o.f./2), (d.o.f. = number of the degrees of freedom). Popular SUSY models: CMSSM, NUHM1, NUHM2, NMSSM, and MSSM with non-universal gaugino masses are examined, to see if this bound on Delta is respected. A more general approach shows that the covariance matrix of a model encodes all the information about the EW fine tuning provided that v=v(p_i) and is therefore more fundamental than Delta. The latter may thus be less relevant for the viability of a model, as long as with v=v(p_i) a good fit of the data is still possible.

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