Tevatron - Discoveries

Discoveries

The Tevatron confirmed the existence of several subatomic particles that were predicted by theoretical particle physics, or gave suggestions to their existence. In 1995, the CDF experiment and DØ experiment collaborations announced the discovery of the top quark, and by 2007 they measured its mass to a precision of nearly 1%. In 2006, the CDF collaboration reported the first measurement of B_s oscillations, and observation of two types of sigma baryons. In 2007, the DØ and CDF collaborations reported direct observation of the "Cascade B" (Ξ−
b) Xi baryon.

In September 2008, the DØ collaboration reported detection of the Ω−
b, a "double strange" Omega baryon with the measured mass significantly higher than the quark model prediction. In May 2009 the CDF collaboration made public their results on search for Ω−
b based on analysis of data sample roughly four times larger than the one used by DØ experiment. The mass measurements from the CDF experiment were 6,054.4±6.8 MeV/c2 and in excellent agreement with Standard Model predictions, and no signal has been observed at the previously reported value from the DØ experiment. The two inconsistent results from DØ and CDF differ by 111±18 MeV/c2 or by 6.2 standard deviations. Due to excellent agreement between the mass measured by CDF and the theoretical expectation, it is a strong indication that the particle discovered by CDF is indeed the Ω−
b. It is anticipated that new data from LHC experiments will clarify the situation in the near future.

On July 2, 2012, two days before a scheduled announcement at the Large Hadron Collider (LHC), scientists at the Tevatron collider from the CDF and DØ collaborations announced their findings from the analysis of around 500 trillion collisions produced since 2001: They found that the existence of the Higgs boson was likely with a mass in the region of 115 to 135 GeV. The statistical significance of the observed signs was 2.9 sigma, which meant that there is only a 1-in-550 chance that a signal of that magnitude would have occurred if no particle in fact existed with those properties. The final analysis of data from the Tevatron did however not settle the question of whether the Higgs particle exists. Only when the scientists from the Large Hadron Collider announced the more precise LHC results on July 4, 2012, with a mass of 125.3 ± 0.4 (CMS) or 126 ± 0.4 (ATLAS) respectively, was there strong evidence through consistent measurements by the LHC and the Tevatron for the possible existence of a Higgs particle at that mass range.