The charm quark, charmed quark or c quark (from its symbol, c) is the third-most massive of all

quark A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly ...

s, a type of

elementary particle In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions ( quarks, leptons, ...

. Charm quarks are found in

hadron In particle physics, a hadron (; grc, ἁδρός, hadrós; "stout, thick") is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules that are held together by the ...

s, which are

subatomic particle In physical sciences, a subatomic particle is a particle that composes an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a p ...

s made of quarks. Examples of hadrons containing charm quarks include the J/ψ meson (),

D meson The D mesons are the lightest particle containing charm quarks. They are often studied to gain knowledge on the weak interaction. The strange D mesons (Ds) were called "F mesons" prior to 1986. Overview The D mesons were discovere ...

s (),

charmed Sigma baryon ''Charmed'' is an American fantasy drama television series created by Constance M. Burge and produced by Aaron Spelling and his production company Spelling Television, with Brad Kern serving as showrunner. The series was originally broadcas ...

s (), and other charmed particles. It, along with the

strange quark The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons ( ...

, is part of the second generation of matter, and has an

electric charge Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons res ...

of + ''e'' and a

bare mass In quantum field theory, specifically the theory of renormalization, the bare mass of an elementary particle is the limit of its mass as the scale of distance approaches zero or, equivalently, as the energy of a particle collision approaches infini ...

of . Like all

s, the charm quark is an

elementary Elementary may refer to: Arts, entertainment, and media Music * ''Elementary'' (Cindy Morgan album), 2001 * ''Elementary'' (The End album), 2007 * ''Elementary'', a Melvin "Wah-Wah Watson" Ragin album, 1977 Other uses in arts, entertainment, a ...

fermion In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Generally, it has a half-odd-integer spin: spin , spin , etc. In addition, these particles obey the Pauli exclusion principle. Fermions include all quarks and ...

with

spin Spin or spinning most often refers to: * Spinning (textiles), the creation of yarn or thread by twisting fibers together, traditionally by hand spinning * Spin, the rotation of an object around a central axis * Spin (propaganda), an intentionally ...

, and experiences all four fundamental interactions:

gravitation In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stron ...

electromagnetism In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions o ...

weak interaction In nuclear physics and particle physics, the weak interaction, which is also often called the weak force or weak nuclear force, is one of the four known fundamental interactions, with the others being electromagnetism, the strong interaction ...

s, and

strong interaction The strong interaction or strong force is a fundamental interaction that confines quarks into proton, neutron, and other hadron particles. The strong interaction also binds neutrons and protons to create atomic nuclei, where it is called th ...

s. The antiparticle of the charm quark is the charm antiquark (sometimes called ''anticharm quark'' or simply ''anticharm''), which differs from it only in that some of its properties have equal magnitude but opposite sign. The existence of a fourth quark had been speculated by a number of authors around 1964 (for instance by James Bjorken and Sheldon Glashow), but its prediction is usually credited to Sheldon Glashow, John Iliopoulos and

Luciano Maiani Luciano Maiani (born 16 July 1941, in Rome) is a Sammarinese physicist best known for his prediction of the charm quark with Sheldon Glashow and John Iliopoulos (the "GIM mechanism"). Academic history In 1964 Luciano Maiani received his degree in ...

in 1970 (see GIM mechanism). Glashow is quoted as saying, "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it brought to the subnuclear world." The first charmed particle (a particle containing a charm quark) to be discovered was the J/ψ meson. It was discovered in 1974 by a team at the

Stanford Linear Accelerator Center SLAC National Accelerator Laboratory, originally named the Stanford Linear Accelerator Center, is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S. Departme ...

(SLAC), led by Burton Richter, and one at the Brookhaven National Laboratory (BNL), led by

Samuel Ting Samuel Chao Chung Ting (, born January 27, 1936) is a Chinese-American physicist who, with Burton Richter, received the Nobel Prize in 1976 for discovering the subatomic J/ψ particle. More recently he has been the principal investigator in res ...

. The 1974 discovery of the (and thus the charm quark) ushered in a series of breakthroughs which are collectively known as the '' November Revolution''.

Hadrons containing charm quarks

Some of the

s containing charm quarks include: *

s contain a charm quark (or its antiparticle) and an up or

down quark The down quark or d quark (symbol: d) is the second-lightest of all quarks, a type of elementary particle, and a major constituent of matter. Together with the up quark, it forms the neutrons (one up quark, two down quarks) and protons (two up ...

. * mesons contain a charm quark and a

. * There are many

charmonium In particle physics, quarkonium (from quark and -onium, pl. quarkonia) is a flavorless meson whose constituents are a heavy quark and its own antiquark, making it both a neutral particle and its own antiparticle. Light quarks Light quarks ( up ...

states, for example the particle. These consist of a charm quark and its antiparticle. * Charmed baryons have been observed, and are named in analogy with strange baryons (e.g. ).

Hadrons containing charm quarks

See also

References

Further reading