New Particle Discovered At Fermilab; Existence Confirmed

This time it appears to be genuine. Fermilab has indeed detected a new particle the Xi-sub-b baryon.

A few days ago Fermilab got the entire physics community excited by announcing that it was almost sure of a discovery of a new particle the W/Z-bar boson. We covered the sensational news here. It turns out that it was not the case.

The CDF detector, where the new particle was detected

The particle

A baryon is a particle (technically, a bound state’) of three quarks. A proton is an example and is made up of two up and one down quark. Apart from these two types, there are four more types of quarks top(some people call it truth’), bottom (some prefer beauty’), strange and charm. The top quark is the most massive, followed by bottom, charm and strange in that order. The Xi-sub-b baryon has an up quark, a strange quark and a bottom quark. The discovery was made yesterday and reported today in Fermilab’s press release.

The standard model list for the quarks and all other fundamental particles.

The Xi-sub-b baryon is extremely unstable, being able to travel just a fraction of a millimetre before disintegrating into lighter particles. The particle was detected in the CDF detector.

Confidence levels

There have been 25 isolated detections, or events, that confirm the existence of the new particle. As we mentioned in earlier posts, the criteria for a discovery is confidence level’. We need a minimum of five-sigma confidence level, or a confidence of more than 99.997% that a certain detection is genuine. Here, Fermilab, after data analysis, puts the confidence level at seven sigma, much higher than the threshold!

The details of the discovery have been sent to Physical Review Letters (PRL) for publication.

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