# Vacuum Instabilities with a Wrong-Sign Higgs-Gluon-Gluon Amplitude

 Title: Vacuum Instabilities with a Wrong-Sign Higgs-Gluon-Gluon Amplitude Author: Reece, Matthew Citation: Reece, Matthew. 2013. Vacuum instabilities with a wrong-sign Higgs-gluon-gluon amplitude. New Journal of Physics 15(4): 043003. Full Text & Related Files: vacuum_instabilities.pdf (1.082Mb; PDF) Abstract: The recently discovered 125 GeV boson appears very similar to a Standard Model Higgs, but with data favoring an enhanced $$h \rightarrow \gamma \gamma$$ rate. A number of groups have found that fits would allow (or, less so after the latest updates, prefer) that the $$ht \bar t$$coupling have the opposite sign. This can be given meaning in the context of an electroweak chiral Lagrangian, but it might also be interpreted to mean that a new colored and charged particle runs in loops and reinforces the W-loop contribution to hFF, while also producing the opposite-sign hGG amplitude to that generated by integrating out the top. Due to a correlation in sign of the new physics amplitudes, when the SM hFF coupling is enhanced the hGG coupling is decreased. Thus, in order to not suppress the rate of $$h \rightarrow WW$$ and $$h \rightarrow Z Z$$, which appear to be approximately Standard Model-like, one would need the loop to “overshoot,” not only canceling the top contribution but producing an opposite-sign hGG vertex of about the same magnitude as that in the SM. We argue that most such explanations have severe problems with fine-tuning and, more importantly, vacuum stability. In particular, the case of stop loops producing an opposite-sign hGG vertex of the same size as the Standard Model one is ruled out by a combination of vacuum decay bounds and LEP constraints. We also show that scenarios with a sign flip from loops of color octet charged scalars or new fermionic states are highly constrained. Published Version: doi:10.1088/1367-2630/15/4/043003 Other Sources: http://arxiv.org/abs/1208.1765 Terms of Use: This article is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#OAP Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:10445584 Downloads of this work: