A Predicted Hadron Has Been Found

A Hadron is a kind of particle, made of quarks. There are two kinds of hadrons, baryons (made out of three quarks) and mesons (made out of a quark and a quirky quark known as an antiquark).

The particle of interest is made up of an up quark, a strange quark, and a heavy bottom quark. I’ve known a few bluegrass bands that fit that description, but this particle is called the Xi-sub-b baryon.

The observation was made at the Collider Detector at Fermilab (CDF) .

The neutral Xi-sub-b belongs to the family of bottom baryons, which are about six times heavier than the proton and neutron because they all contain a heavy bottom quark. The particles are produced only in high-energy collisions, and are rare and very difficult to observe*.


  1. #1 surgoshan
    July 22, 2011

    So… mass?

  2. #2 Greg Laden
    July 22, 2011


  3. #3 Eric Lund
    July 22, 2011

    @1: The link gives a mass of 5.7878 GeV/c2. That’s a bit more than six times the mass of the proton.

  4. #4 bks
    July 22, 2011

    Unfortunately, no news on Higgs this year. Particle physics *appears* to be in a foundational crisis, but I freely admit that it is outside my area of expertise.


  5. #5 josh
    July 22, 2011

    For perspective, assuming the mass @3 is correct, that’s not much heavier than the b-quark itself (~4.7 GeV) and much lighter than the top quark (~173 GeV). The Higgs is thought to be in the range greater than but close to 114 GeV, although there are some ways to get around this. Supersymmetric partners are theoretically in the 100-1000s GeV range. The proton however (~1 GeV as mentioned above) is made of up and down quarks which are < 0.01 GeV.