The vertical axis shows the number of events – where each event is the production of a W boson and a pair of particle jets – in proton-antiproton collisions at the Tevatron. The horizontal axis shows the mass of the pair of jets. Physicists expected the number of events to fall off as the mass of the jet pairs rose (red), but instead they observed a bump. The extra events may have been created by mysterious new particles (Image: CDF collaboration)
We propose that the 3.2 standard deviation excess at about 150 GeV in the dijet mass spectrum of W + jets reported by CDF is the technipion Xt of low-scale technicolor. Its relatively large cross section is due to production of a narrow Wjj resonance, the technirho, which decays to W *T . We discuss ways to enhance and strengthen the technicolor hypothesis and suggest companion searches at the Tevatron and LHC.
New Scientist – the physics world is buzzing with news of an unexpected sighting at Fermilab’s Tevatron collider in Illinois – a glimpse of an unidentified particle that, should it prove to be real, will radically alter physicists’ prevailing ideas about how nature works and how particles get their mass.
Physicists are 99.9 per cent sure it is not a fluke, so they are understandably anxious to pin down the particle’s identity.
Most agree that the mysterious particle is not the long-sought Higgs boson, believed by many to endow particles with mass. “It’s definitely not a Higgs-like object,” says Rob Roser, a CDF spokesperson at Fermilab. If it were, the bump in the data would be 300 times smaller. What’s more, a Higgs particle should most often decay into bottom quarks, which do not seem to make an appearance in the Fermilab data.
In a new paper, Lane, Eichten and Fermilab physicist Adam Martin suggest that a technipion with a mass of about 160 GeV could be the mysterious particle producing the two jets. “If this is real, I think people will give up on the idea of looking for the Higgs and begin exploring this rich world of new particles,” Lane says.
We report a study of the invariant mass distribution of jet pairs produced in association with a W boson using data collected with the CDF detector which correspond to an integrated luminosity of 4.3 fb^-1. The observed distribution has an excess in the 120-160 GeV/c^2 mass range which is not described by current theoretical predictions within the statistical and systematic uncertainties. In this letter we report studies of the properties of this excess.