physics electrostatic

Subject: physics electrostatic Sun Jun 21, 2009 11:43 am

what is meant about quarks.please tell me details

Active member

A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the best-known of which are protons and neutrons. They are the only particles in the Standard Model to experience all four fundamental interactions, also known as fundamental forces. Due to a phenomenon known as color confinement, quarks are never found in isolation; they can only be found within hadrons. For this reason, much of what is known about quarks has been drawn from observations of the hadrons themselves.

There are six different types of quarks, known as flavors: up, down, charm, strange, top, and bottom. Up and down quarks have the lowest masses of all quarks. The heavier quarks rapidly change into up and down quarks through a process of particle decay: the transformation from a higher mass state to a lower mass state. For this reason, up and down quarks are generally stable and the most common in the universe, and charm, strange, top and bottom quarks can only be produced in high energy collisions (such as those involving cosmic rays and in particle accelerators).

The quark model was independently proposed by physicists Murray Gell-Mann and George Zweig in 1964.Quarks were introduced as parts of an ordering scheme for hadrons, and there was little evidence for their physical existence until 1968. All six flavors of quark have since been observed in accelerator experiments; the top quark, first observed at Fermilab in 1995, was the last to be discovered