Dealing with the signal strength modifier of the Higgs, a few things escape my grasp :
1/ In the PDG booklet the combined result is presented with an uncertainty, although some of the measured signals below are inequalities. How do we combine inequalities and equalities to obtain that result ?
2/ I tried recovering that result using inverse-variance weighting but two problems arise : -some measurements have two unequal uncertainties; for instance, for ZZ* it's +0.12 -0.11.
-the other problem, is that inverse-variance weighting should concern different measurements of the same thing (for instance, combing different measurements of the ZZ signal), here it would be combining measurements of different signals which shouldn't make sens (although I obtained the same result for the combined final states when I ignored the inequalities and chose one uncertainty for each measurement).
3/Last but not least, in this review "Dark Matter through the Higgs portal", by Arcadi, Djouadi and Raidal, they turn a measured result with an uncertainty into an inequality (implication 23). HOW ? I don't even know what to look up to find this :