Two things are 100% certain because they appeared in an official statement from CERN:
- Neither experiment will announce the discovery of the Higgs, in the sense of a signal with a significance of 5 sigma.
- Neither experiment will exclude the Standard Model Higgs over the whole low-mass range.
- The Standard Model Higgs boson is excluded down to approximately 130 GeV, but not below.
- As already reported widely on blogs, both experiments have an excess of events consistent with the Higgs particle of mass around 125 GeV.
- The excess is larger at ATLAS, where it is driven by the H→γγ channel, and supported by 3 events reconstructed in the H→ZZ*→4l channel at that mass. The combined significance is around 3 sigma, the precise number depending on statistical methods used, in particular on how one includes the look-elsewhere-effect.
- CMS has a smaller excess at 125 GeV, mainly in the H→γγ channel. They have 3 events in H→4l as well, but they are oddly shifted to somewhat lower masses of order 119 GeV. All in all, the significance at 125 GeV in CMS is only around 2 sigma.
- With some good faith, one could cherish other 2-sigmish bumps in the γγ channel, notably around 140 GeV. Those definitely cannot be the signal of the Standard Model Higgs, but could well be due to Higgs-like particles in various extensions of the Standard Model.
You're of course welcome to fill in more details or paste an excerpt of the ATLAS or CMS draft into the comment section ;-)