That's not enough, is it? I thought in particle physics, people wanted 5 standard deviations? Does someone know why this is being published then?
However, all the numbers are, well, arbitrary. By that I mean that there is nothing special about 3 sigma or 5 sigma or p-value less than 0.05. The actual value is arbitrary and used because it has high inertia, i.e. commonly used in literature.
And yes, the exact numbers are arbitrary, but their ballpark isn't. You reduce the necessary certainty if you have confidence on your priors, and increase it if you test many different hypotheses. The target confidence also varies from one discipline to another based on how much data one can realistically gather, but nearly all of physics falls on the "we can gather enough data" category anyway.
How many measurements do they make at CERN? They probably see random 3 sigma measurements fairly often.
On the other hand, almost nobody believed the FTL Neutrino incident was real even if the signal was stronger than 5 sigma. Extraordinary claims still require extraordinary evidence.
IANP and everything.
3.1 is better than 1, so people think about it more than they think about 1, but less than they think about 5. This is how science _actually_ works.
And from a more academic point of view, although this is not a new discovery, it can be an interesting line of research. If they have used all the available data and they could only get sigma 3, I think it makes sense to publish what you got in order to justify spending your time trying to either make that a five or discard the hypothesis.
So while you're correct that the 3 sigma is quite a low significance by particle physics standards, it is consistent with previous measurements which yielded similar anomalies, presumably at lower significance.
