It is always good to see science covered in the mainstream media. It is equally disheartening to see misinterpretation of scientific results. I am sure you’ve been hearing a lot about the “discovery” of the Higgs Boson particle, also (unfortunately) coined as the “God particle”. If you are not a physicist, you might find difficulty in interpreting the results. So, here is a particle physics 101 so that you can make your own opinion about the results.

In particle physics (as in some other fields), results are statistical and are always presented with a “sigma” or standard deviation(s) away from the expected result (given by models). A higher value of sigma indicates a higher certainty of a given measurement. So, a six sigma signal is very promising and a two sigma signal is of almost no significance. So, a 3-sigma result, which means it has one in 740 chance of being a false signal, 4-sigma has one is 32, 000 and 5-sigma has one in 3.5 million.

With experience from past discoveries and false signals, some standards have been adopted in order to judge the value of a result. Here is the key:

3-sigma: some evidence/promising hint

4-sigma: likely discovery

5-sigma and higher: confirmed discovery

Yesterday, US based Tevatron, which has been unfortunately decommissioned, announced a 2.9 sigma Higgs signal based on their analysis of archival data. Tomorrow, we are going to hear from CMS and ATLAS groups at CERN about their findings. I will let you make your own opinion!