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I'm currently studying at the spectra of some supersymmetric models, and would like to know whether the parameter points I'm looking at are ruled out due to excessive CP violation.

I am using SPheno, which allows me to test my spectra against various other experimental bounds. It provides a Block SPhenoLowEnergy in its SLHA output that has, for example, the predicted branching ratio $B_s \rightarrow \mu\mu$, or the anomalous muon $g-2$.

What's the variable to look for when one colloquially says "ruled out because of CP violation"? How to get it in SPheno (or with any other spectrum generator / event generator, I can switch)? I feel like the answer is obvious but I'm missing the forest for the trees.

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Why do you anticipate extra sources of CP violation? Are you using complex Lagrangian parameters? If so, the best experimental limits might be contributions to electric dipole moments, permitted only at three-loops in the SM, and possibly limits on CP violation in the Higgs sector.

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Thanks. I have some negative mass parameters at the GUT scale (e.g. $M2$), but not negative squared masses, so I don't believe I have complex parameters - at least it was not my intention to introduce them. I was just told in passing by a colleague "Negative mass parameters? That's bad, you'll have too much CP violation!", although he couldn't tell me how exactly, or where he got that. –  jdm Apr 20 '13 at 17:48
Even negative squared masses don't need count as complex parameters. Cf. the normal EWSB Lagrangian with negative $\mu^2$ - that's a perfectly reasonable, unitary theory, it's just that $\mu^2$ cannot be interpreted as a mass. –  Vibert Apr 21 '13 at 11:26
Complex soft-breaking gaugino masses, trilinears, or $\mu$ could lead to CP violation, though not all complex phases are physical - only combinations. Other soft-breaking terms are not permitted complex phases, because the Lagrangian must be real. I agree that e.g. $m_{H_u}^2$ could be considered a parameter unto itself, rather than the square of a real number. But $\mu^2<0$ is typically considered unphysical in programs that calculate the MSSM mass spectrum. Can $\mu^2<0$ models be phenomenologically acceptable? Even with no other complex phases? I appreciate that it needn't lead to tachyons –  innisfree Apr 21 '13 at 16:21

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