1. ATLAS Collaboration, Phys. Lett. B 716, 1 (2012). arXiv:1207.7214
2. CMS Collaboration, Phys. Lett. B 716, 30 (2012). arXiv:1207.7235
3. A. Strumia, J. High Energy Phys. 1104, 073 (2011). arXiv:1101.2195 , see for example
4. R. Barbieri, D. Pappadopulo, J. High Energy Phys. 0910, 061 (2009). arXiv:0906.4546
5. M. Papucci, J.T. Ruderman, A. Weiler, J. High Energy Phys. 1209, 035 (2012). arXiv:1110.6926