Physicists had expected to find the particle after a 1977 Fermilab experiment turned up evidence for the bottom quark
, a particle that needed a partner.
Seven other baryons containing a single bottom quark
have been confirmed so far, including a sibling of the new particle with a down quark instead of an up quark, found by Fermilab scientists in 2007.
The standard model of particle physics predicts the existence and mass of this particle, which is a baryon, like protons and neutrons, and is made up of two strange quarks and a bottom quark
Proton's cousin Physicists discover omega-b-minus, a particle made of two strange quarks and a bottom quark
(SN: 9/27/08, p.
Physicists had long conjectured that a down quark could combine with a strange and a bottom quark
to form the three-generation cascade baryon.
Ordinary matter, such as protons and neutrons, contains only up quarks and down quarks, whereas the sigma-bs each contain a bottom quark
and either a pair of up quarks or a pair of down quarks.
The fireball of electron-positron annihilation spat out a particle that promptly decayed into a bottom quark
and its antimatter counterpart.
The newly discovered top quark is the long-sought partner of the bottom quark
With the 1977 discovery at Fermilab of the bottom quark
, the search was on for the top quark.
Discovered in 1977, B mesons consists of a bottom quark
paired with an anti-up or an andi-down quark.
The theory requires that quarks come in pairs, and only the bottom quark
has no partner so far.
Their result for the mass of the bottom quark
is only a few percent away from the experimentally determined value.
Other answers may come from renewed efforts to understand the behavior of the bottom quark
. And particle physicists are pushing forward their search for the still-undiscovered top quark and a fifth force of nature required by the standard model to determine the masses of the elementary particles.
The strange quark has a mass of about 0.5 GeV, the charm quark about 1.5 GeV and the bottom quark
about 4.5 GeV.