Why was Higgs not discovered at Tevatron?

[Silversonic]

As far as I can tell Tevatron was able to identify relative to background an excess in decay processes in the range from 105 to 145 GeV. But what was different with Tevatron that didn't allow it to discover the Higgs before the LHC? The LHC had double the CM-energy but the Higgs could've still been produced at Tevatron. Was the Higgs cross section at Tevatron's 2TeV too low to produce statistically significant results to confirm the Higgs? I have looked around but haven't come across a straight up answer.

 

[jtbell]

The Tevatron results for the Higgs were at only the 2.9 sigma (= 2.9 standard deviations) level of statistical significance. A long-standing convention in experimental HEP is that you need at least 5 sigma in order to claim a discovery.

They didn't have enough events either because the cross-section was too low at their energy, as you suggest, or the luminosity (basically the number of collisions per second that could lead to Higgs production) was too low. I don't know which factor was more important.

 

[Vanadium 50]

See https://www.physicsforums.com/showthread.php?t=717524

 

[mfb]

The Tevatron results for the Higgs were at only the 2.9 sigma (= 2.9 standard deviations) level of statistical significance. A long-standing convention in experimental HEP is that you need at least 5 sigma in order to claim a discovery.

5 sigma ("there is something unless we made a measurement error") is usually called an observation, 3 sigma ("there could be something but we are not sure") is often called discovery.