Eur. Phys. J. C (2013) 73: 2563
https://doi.org/10.1140/epjc/s10052-013-2563-y

Regular Article - Theoretical Physics

Should we still believe in constrained supersymmetry?

¹ School of Physics, Monash University, Melbourne, Victoria, 3800, Australia
² ARC Centre of Excellence for Particle Physics at the Tera-scale, Monash University, Melbourne, Victoria, 3800, Australia
³ Monash Centre for Astrophysics, Monash University, Melbourne, Victoria, 3800, Australia
⁴ School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3JZ, UK
⁵ School of Physics, The University of Melbourne, Melbourne, Victoria, 3010, Australia
⁶ ARC Centre of Excellence for Particle Physics at the Tera-scale, The University of Melbourne, Melbourne, Victoria, 3010, Australia

^* e-mail: benjamin.farmer@monash.edu

Received: 7 February 2013
Revised: 14 August 2013
Published online: 1 October 2013

Abstract

We calculate partial Bayes factors to quantify how the feasibility of the constrained minimal supersymmetric standard model (CMSSM) has changed in the light of a series of observations. This is done in the Bayesian spirit where probability reflects a degree of belief in a proposition and Bayes’ theorem tells us how to update it after acquiring new information. Our experimental baseline is the approximate knowledge that was available before LEP, and our comparison model is the Standard Model with a simple dark matter candidate. To quantify the amount by which experiments have altered our relative belief in the CMSSM since the baseline data we compute the partial Bayes factors that arise from learning in sequence the LEP Higgs constraints, the XENON100 dark matter constraints, the 2011 LHC supersymmetry search results, and the early 2012 LHC Higgs search results. We find that LEP and the LHC strongly shatter our trust in the CMSSM (with M ₀ and M _1/2 below 2 TeV), reducing its posterior odds by approximately two orders of magnitude. This reduction is largely due to substantial Occam factors induced by the LEP and LHC Higgs searches.