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Higgs Signal Gains Strength
ananyo writes "Today the two main experiments at the Large Hadron Collider, the world's most powerful particle accelerator, submitted the results of their latest analyses. The new papers (here here and here) boost the case for December's announcement of a possible Higgs signal. Physicists working on the In the case of the Compact Muon Solenoid experiment, have been able to look at another possible kind of Higgs decay, and that allows them to boost their Higgs signal from 2.5 sigma to 3.1 sigma. Taken together with data from the other detector, ATLAS, Higgs' overall signal now unofficially stands at about 4.3 sigma."
Certainty ? from a scientific point of view ? infinite! Sigmas in a way tells how probable is to get these results, the more sigmas you have means that the more improbable to get these results without invoking some other model/theory etc etc. So 4.3 is good but not good enough, we need at least 5 sigmas. (What said is not 100% correct, but a rough explanation) http://en.wikipedia.org/wiki/Standard_deviation
4.3 sigma corresponds to a confidence level of 99,998292% (credit to Wolfram|alpha). This is about as certain as death and taxes if compared to “everyday” events, but maybe it's not enough for theoretical physicists (I'm not one).
I think they usually require 5 sigma (99.9999426697%) for it to be official.
Stupidly assuming you're talking American "football", 119.99993120364 yards, or 0.00247666896 inches from the line.
You managed to get the values for both 3 sigma, and 5 sigma wrong
+/- 3 sigma = 1 in 370 (which is what clued me into them being wrong, 1/81 + 0.997 isn't close to 1)
+/- 5 sigma = 1 in 1,744,278
All this is under pure mathematician's "null-hypothesis" assumptions. That is, we have a 99.999999999% confidence level of being right, unless we are making any mistake in our set of thousands of assumptions, there is any miscalibration, any fundamental error, systematic errors, ...
But this is not a mathematical exercise. It is a physics experiment. Knowing how the CMS/ATLAS collaboration works and how politized it is, If there is a (subtle but likely) mistake, then this number means nothing.
The correct reading would be: "we are 99.99999999% (or whatever) sure that if we are wrong it is not due to a purely random statistic fluctuation"
Other than that 5-sigma is a mere convention on when to trigger a press conference to declare "discovery"