The Tevatron collider has been shot down last September so the amount of data has not increased since the last Higgs update at the Moriond conference in March. Nevertheless, the collaborations are still able to make adiabatic improvements in the analysis, especially now when they know where the Higgs is. At Moriond, the Higgs-like excess was observed mostly in the b-bbar final state by the CDF collaboration; what changed today is that D0 observes a (somewhat smaller) excess in the same channel, making the claim more credible. All in all, the combined (local) significance of the Higgs excess at the Tevatron reaches the maximum of 3 sigma for mh=120 GeV, although it's more like 2.7 sigma at the true value of mh=125 GeV. 
However, there is an aspect of the data presented today that is more interesting than the sigma pissing contest. The Tevatron experiments are most sensitive to the Higgs boson decaying into a pair of b-quarks and produced in association with a W or Z boson. What they're testing is thus the Higgs couplings to electroweak gauge bosons and to b-quarks, both of which are central to establishing the higgsy nature of the newly discovered particle. In particular, the Tevatron data are suggesting that the particle indeed decays frequently into b-quarks (which, according to the Standard Model, should happen about 60% of the times). Thus, the Tevatron provides an important piece of the puzzle that, at the moment, is not available from the LHC. Actually, the rate observed in the VH→bb channel is 2±0.7 larger than predicted by the Standard Model, adding up to other intriguing hints of a non-standard Higgs behavior.By the end of the year the LHC experiments should reach a comparable sensitivity in the same channel, clarifying whether the Tevatron excess was the real thing, or a classic look-here effect...
I *love* your counter.
ReplyDeleteThe posts are not bad either.
Unfortunately I can never give this result the credit it deserves because of the timing. They have tried too hard to find something, and never found it (except in the wrong place) until the right mass was found at the LHC and it would have been a mystery why it wasn't found here too.
ReplyDeleteNo-one cares what I think, but in my mind, even though a thousand people may have contributed to this result I give it as much weight as if they had just made it up.
@BJ: agreed. It seems to me that they want a piece of the cake. Similarly, I could present my theory on the plausability of a Higgs which comprises of two gluons (on the basis of "it makes sense now") on a press conference later today, but it made sense only after the LHC data, so we're looking forward to tomorrow's event with champagne and all :)
ReplyDeletetricky... how can we accommodate in theory for the diphoton and the bottom branching ratios to be simultaneously enhanced? The top-partner of your day-3 post cannot easily do the job alone, I guess.
ReplyDeleteyeah, no simple model can explain the Tevatron rate twice the SM
ReplyDeleteBJ and Csiki: you're saying you think they falsified their results? That would be quite remarkable!
ReplyDelete