Related Links  (Outside this Site)

A strength test for the strong force.  Sarah Charley  (Symmetry, 2017-03-10)
Who proposed the  color  charge?   (StackExchange, 2017-07-12)
Fundamental forces  by  Rod Nave  (Hyperphysics).

In 1968,  James D. Bjorken (1934-)  found the first convincing evidence of the composite nature of  hadrons  in  deep inelastic scattering expriments.  The components were called partons by Richard Feynman  and are now known as quarks, antiquarks and gluons.  Supervised by  Sydney Drell (1926-2016),  Bjorken conjectured that those particles behave in the main like free particles with respect to high-momentum exchanges.  An idea on which Feynman insisted as he presented his  parton  model and which would eventually become known as  asymptotic freedom  (an expression coined by Gross and Wilczek in 1973).
 
The term "quark" was famously coined by  Murray Gell-Mann.  The word "gluon" was first used by  Edward Teller (1908-2003)  for something entirely different.
 
Asymptotic freedom  was the cornerstone of the theory of strong nuclear interactions for which the  2004 Nobel prize in physics  was awarded to  David Gross (1941-)  and  Frank Wilczek (1951-)  along with  David Politzer (1949-)  who came to the same conclusions independently.

(2018-06-27)  The Birth of Color   (1966)
Preludes to  quantum chromodynamics.

Yoichiro Nambu (1921-2015)   |   Moo-Young Han (1934-2016)   |   Oscar Greenberg (1932-)

(2018-07-18)  Isospin   (Isotopic Spin)
It resembles  (quantized)  spin  in a  disembodied  Hilbert space.

Isospin

(2018-08-11)  Bootstrap Theory   (1961)
Nuclear Democracy :  No hadron is more elementary than any other...

When Gell-Mann later introduced quarks as constituents of all observable hadrons, p; he remarked in jest that the hadronic bootstrap principle still holds:  No  observable  hadron is more elementary than any other  (vacuously so,  since none of them are elementary).  Gell-Mann liked the bootstrap principle but remarked that it need not be confined to a purported opposition between QFT and dispersion methods  (S-matrix theory).

S-Matrix   |   Bootstrap model (1961)   |   Geoffrey Chew (1924-;  Ph.D. 1948)   |   Steve Frautschi (1933-)
New discoveries using bootstrap  by  Natalie Wolchover  (Quanta, 2017-02-23).
 
The bootstrap theory (2:20)  by  Murray Gell-Mann  (1998).

(2018-06-23)  The  8  Gell-Mann  unitary matrices.
Traceless  and  Hermitian.  The  eightfold way  (1961).

The  Gell-Mann matrices  are to SU(3) what  Pauli matrices  are to SU(2).

l1  =

0  1 0

1  0 0

0  0 0

l2  =

0  i 0

-i  0 0

0  0 0

l3  =

1  0  0

0  -1  0

0  0 0

l4  =

0  0  1

0  0  0

1  0 0

l5  =

0  0 i

0  0 0

-i  0 0

l6  =

0  0 0

0  0 1

0  1 0

l7  =

0  0 0

0  0 i

0  -i 0

l8  =

1 Ö3

1  0  0

0  1  0

0  0 -2

Gell-Mann had tried to brute-force his way into a suitable group with up to 7 generators during his 1959-60 stay at the  Collège de France,  especially in the fall of 1959. 

In the Fall of 1960,  Dick Block  (Richard Earl Block,  b. 1931,  Ph.D. 1956)  was a young assistant professor of mathematics at Caltech,  who had recently completed his Ph.D. dissertation on Lie Algebras at  Chicago,  under A. Adrian Albert (1905-1972).  Block pointed out to Gell-Mann that he was re-inventing the wheel:  The problem was about simple Lie groups in canonical form and the solution was well-known...

Therefrom came Gell-Mann's interest in SU(3) which  worked beautifully  [sic].  Gell-Mann was the first to call  gluons  the  8  vector bosons associated to the above generators  (the word itself had been introduced by  Edward Teller (1908-2003)  in an unrelated context). 

At the time,  George Zweig (1937-)  was working at CERN,  just after getting his doctorate,  on a similar scheme based on four  aces  rather than three  quarks.

Yuval Ne'eman (1925-2006)  also came to the same conclusion around the same time,  as he obtained his Ph.D. under Abdus Salam (1926-1996) at  Imperial College London  (Ne'eman was  military attaché  at the nearby Israeli embassy).

The discovery of the  W^-,  in February 1964,  can be construed as the experimental confirmation of  SU(3)  symmetry in hadrons.  Both Gell-Mann and Ne'eman were involved.  This paved the way for the  quark  proposal shortly thereafter.

Noble Eightfold Path (Buddhism)   |   Gell-Mann matrices
Groping for SU(3) (4:02)  by  Murray Gell-Mann  (1998).
Most-Cited Rewritten Eightfold-Way Paper of 1962 (3:53)  by  Murray Gell-Mann  (1998).
 
Numericana :   Pauli matrices   |   Laws of Nature

(2018-06-19)  Quantum  Chromodynamics   (QCD)
SU(3):  The unbroken symmetry of  color charges.

Murray Gell-Mann (1929-2019)   |   Harald Fritzsch (1943-)   |   George Zweig (1937-)

(2023-07-28)  Deep Inelastic Scattering  (SLAC-MIT, 1967)
Electrons probing protons (and bound neutrons) at high energies.

This was the first direct experimental evidence for  quarks.

Nobel 1990  |  Henry W. Kendall (1926-1999)  |  Richard E. Taylor (1929-2018)  |  Jerome I. Friedman (1930-)

(2023-07-28)  Renormalization of Yang-Mills Theories ('t Hooft, 1971)
The Higgs field helps renormalize weak and strong nuclear forces.

Nobel 1999   |   Martinus Veltman (1931-1921)   |   Gerard 't Hooft (1946-)

(2018-06-19)  Asymptotic  Freedom (Gross & Wilczek, 1973)
The  strong force  vanishes at very small distances.

The principle is also valid for weak interactions but it's far more noticeable with high-energy strong interactions.  (A quark of one flavor can transform into a quark of another flavor only through a weak interaction.)

David Gross (1941-)   |   H. David Politzer (1949-)   |   Frank Wilczek (1951-)   |   Nobel 2004
 
Asymptotic freedom (2:03)  by  Murray Gell-Mann  (1998).
Quantum Chromodynamics (11:45)  by  David Gross  (2014-07-24).
Kavli Institute for Theoretical Physics (28:25)  by  David Gross   2009-04-29).
Frank Wilczek (1:22:47)  The Accent Podcast   (2023-03-25).