Almost quantum correlations.

@article{Navascus2015AlmostQC,
  title={Almost quantum correlations.},
  author={Miguel Navascu{\'e}s and Yelena Guryanova and Matty J. Hoban and Antonio Ac{\'i}n},
  journal={Nature communications},
  year={2015},
  volume={6},
  pages={
          6288
        }
}
Quantum theory is not only successfully tested in laboratories every day but also constitutes a robust theoretical framework: small variations usually lead to implausible consequences, such as faster-than-light communication. It has even been argued that quantum theory may be special among possible theories. Here we report that, at the level of correlations among different systems, quantum theory is not so special. We define a set of correlations, dubbed 'almost quantum', and prove that it… 
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