[bjornsing]

Thanks again. But in my mind that doesn’t really explain the Higgs mass prediction/estimate going from 126 +/- 2.2 GeV to 130 GeV… The reason you have that +/- 2.2 GeV is (among other things) that the mass of the top quark mass is uncertain, right? So how could a new measurement of the top quark mass make the prediction for the Higgs mass jump so far (unless the new top quark mass was wildly unexpected)?

[sigmoid10]

I think you misunderstand the way the Higgs mass is calculated here. This is a highly non-linear relationship that is extremely sensitive to the top quark mass. In fact the second most massive quark would only contribute a fraction of one thousandth to the result (which is why it was ignored in the paper).

Consider this toy example: The mass m is calculated from some parameter like m~=b^4 and that parameter b was measured b=2.0±0.1. Using Gaussian error propagation, m would be 16±3.2. Now update the measurement of b just slightly to b=2.1±0.05. That 5% change in b changes the result to m=19.45±1.85 -> more than 20%, and with just one standard deviation of difference in b. The relationship is not linear.

[bjornsing]

That’s a clarifying example. But note that what happened with the Higgs mass was significantly more extreme than your example. All I’m saying is that I found that surprising. But you’re right, it could potentially be an extreme non-linearity that caused the surprise.