Since the late 1980s, experiments have revealed that no more than 20 to 30 percent of a nucleon's spin comes from the spin of its valence quarks
The discovery of yet other combinations of quarks
and antiquarks could illuminate the force that binds quarks
and antiquarks together.
Physicists expect others in the new particle family, like these initial two members, to consist of four quarks
and one antiquark.
Theorists have calculated just how different the decay rates of b and anti-b quarks
The find also underscores the possibility of discovering particles with four or six quarks
That process would briefly liberate the quarks
and gluons that make up protons and neutrons.
Racing to explain the mass discrepancies, some theorists have proposed that the newfound Ds particles are not just mesons but elaborate subatomic "molecules" that include other quarks
, as well.
Besides settling basic quantitative facts about matter, gauging those masses may grant physicists a glimpse within the quarks
themselves to learn what, if anything, lurks there--perhaps more fundamental entities known as strings (SN: 9/22/01, p.
There are currently six known types, or flavors, of quarks
- three light and three heavy.
Until recently, quarks
had been found only in pairs or trios.
It is inappropriate to correspond the three generations of leptons to the three generations of quarks
because all these three generations of leptons are formed or produced directly in association with only the first generation of quarks
e]) and quarks
) come into the consideration.
By now it was well established that quarks
(see 1961) combine two at a time (a quark
and an anti-quark
) to form mesons and three at a time to form protons, neutrons, and other hadrons.
The rediscovery of an exotic particle provides the best evidence yet that quartets of quarks
exist in a universe dominated by two-and three-quark
LR]-type interaction can arise at the tree level in models containing a new charged gauge boson with right-handed couplings to the quarks
(as in left-right symmetric models), in the SM model if it is extended to contain new heavy "exotic" quarks
which have right-handed couplings to the W and which mix with the known quarks
, and in models with leptoquarks.