Slashdot Mirror

Charliemopps writes: "Over the past few years, more and more experiments have started to question one of the core assumptions of the standard model: Lepton Universality. Simply put, the weak nuclear force is assumed to work equally on all Leptons (electron, muon and tau). Two years ago The Babar experimental collaboration reported that measurements indicated this may not have been the case. But the measurements were not accurate enough to be definitive.

Now, a report from The LHC shows that they have analyzed their entire dataset of proton-proton collisions and found a rather large discrepancy. These measurements are still not all that accurate. These decays happen so rarely that even with this huge data set there is still about a 1% change they are incorrect. One explanation for such measurements is an as-yet-undiscovered, charged Higgs particle. It would have to be extremely heavy: greater than 109GeV possibly even as high as 150GeV. This is predicted by some models outside of the Standard Model, like Supersymmetry."

TaeKwonDood writes with news from CERN about more results in the search for the Higgs Boson, this time from the ATLAS experiment. Researchers report peaks in the data in accordance with what they'd expect from the Higgs. The curiosity is that the peaks are a couple GeV away from each other. "The ATLAS analyses in these channels return the best fit Higgs masses that differ by more than 3 GeV: 123.5 GeV for ZZ and 126.6 GeV for gamma-gamma, which is much more than the estimated resolution of about 1 GeV. The tension between these 2 results is estimated to be 2.7sigma. Apparently, ATLAS used this last month to search for the systematic errors that might be responsible for the discrepancy but, having found nothing, they decided to go public." Scientific American has a more layman-friendly explanation available. As this work undergoes review, physicists hope more eyes and more data will shed some light on this incongruity. Tommaso Dorigo, a particle physicist working at the CMS experiment at CERN, writes, "Another idea is that the gamma-gamma signal contains some unexpected background which somehow shifts the best-fit mass to higher values, also contributing to the anomalously high signal rate. However, this also does not hold much water — if you look at the various mass histograms produced by ATLAS (there is a bunch here) you do not see anything striking as suspicious in the background distributions. Then there is the possibility of a statistical fluctuation. I think this is the most likely explanation." Matt Strassler provides a broader update to the work proceeding on nailing down the Higgs boson.

gbrumfiel writes "Researchers at two detectors at the Large Hadron Collider are seeing something unusual. The signal is faint, but it could be from the long-sought Higgs particle. The Higgs is part of the mechanism that gives other particles mass, and it also unifies the electromagnetic and electroweak forces. No one is willing to declare it found just yet, but the new data from the CMS and ATLAS detectors are an independent, 'tantalizing' hint of what's to come. The results were presented today at HEP-2011 in Grenoble, France."