Friday, June 10, 2011

Things that go bump in the data, and live computing

It is time to report again on the bump in the Tevatron data at Fermilab. In April, Fermilab had reported that there was an unexpected bump in the total number of events that produce a W boson and two jets. This bump could not be explained by the standard model. The data was greeted with enthusiasm by some model builders, who rushed to build theories, and scepticism by others, who pointed out that it could be explained by a simple miscalibration of jet energies. However, it was universally agreed that the effect, which was a 3-sigma effect, needed further data before it could be supported or dismissed. Well, further data is now in from the CDF experiment at Fermilab, and the effect hasn't gone away. Instead, it is now a 5-sigma effect (well, 4.8-sigma, if you want to be picky). While the hard headed await further data from other sources like the LHC, phenomenologists have not found it too hard to come up with models that account for the bump. Some of the attempts include the proposal of a new vector boson Z', that needs to be leptophobic (i.e. not decay into leptons, but only into quarks). Aficionados of supersymmetry have come up with a sbottom decaying into a stop, but there are numerous other contenders. Here are the references for the technically inclined.

Theorists versus the CDF bump;

CDF: Wjj bump almost 5 sigma!!!

Meanwhile, at the other end of the spectrum, researchers at Caltech have managed to manipulate strands of DNA into computing a square root. There's a really cute video at

DNA takes square roots

It looks like there are exciting times ahead for scientists of varied interests. It makes for a pleasant change from the days of the doldrums.

Update (11/06/11): Whoops! This is a real roller-coaster ride. The D0 data at the Tevatron, now finds no bump at the earlier reported energies. More info on this when it comes out.

(12/6/11) Here is the way it pans out, as of today. The CDF data shows a clear bump in the distribution of events in the neighbourhood of 150 GeV. The D0 data, carrying out similar analysis shows no bump in this range. The clearest discussion that I found of this is here. The rest awaits further data and analysis.

This blog post is by Neelima Gupte and Sumathi Rao.

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