The timeline of particle physics lists the sequence of particle physics theories and discoveries in chronological order. The most modern developments follow the scientific development of the discipline of
particle physics.
1927 –
Charles Drummond Ellis (along with
James Chadwick and colleagues) finally establish clearly that the beta decay spectrum is in fact continuous and not discrete, posing a problem that will later be solved by theorizing (and later discovering) the existence of the
neutrino.
1964 –
François Englert,
Robert Brout,
Peter Higgs,
Gerald Guralnik,
C. R. Hagen, and
Tom Kibble postulate that a fundamental quantum field, now called the
Higgs field, permeates space and, by way of the
Higgs mechanism, provides mass to all the elementary subatomic particles that interact with it. While the Higgs field is postulated to confer mass on quarks and leptons, it represents only a tiny portion of the masses of other subatomic particles, such as protons and neutrons. In these, gluons that bind quarks together confer most of the particle mass. The result is obtained independently by three groups: François Englert and Robert Brout; Peter Higgs, working from the ideas of Philip Anderson; and Gerald Guralnik, C. R. Hagen, and Tom Kibble.[1][2][3][4][5][6][7]
1964 –
Sheldon Glashow and
James Bjorken predict the existence of the charm quark. The addition is proposed because it allows for a better description of the
weak interaction (the mechanism that allows quarks and other particles to decay), equalizes the number of known
quarks with the number of known
leptons, and implies a mass formula that correctly reproduced the masses of the known
mesons.
1968 –
Stanford University:
Deep inelastic scattering experiments at the
Stanford Linear Accelerator Center (SLAC) show that the
proton contains much smaller, point-like objects and is therefore not an elementary particle. Physicists at the time are reluctant to identify these objects with
quarks, instead calling them partons — a term coined by Richard Feynman. The objects that are observed at SLAC will later be identified as
up and
down quarks. Nevertheless, "parton" remains in use as a collective term for the constituents of
hadrons (quarks,
antiquarks, and
gluons). The existence of the
strange quark is indirectly validated by the SLAC's scattering experiments: not only is it a necessary component of Gell-Mann and Zweig's three-quark model, but it provides an explanation for the
kaon (K) and
pion (π) hadrons discovered in cosmic rays in 1947.
1970 – Glashow,
John Iliopoulos and
Luciano Maiani predict the charmed quark that is subsequently found experimentally and share a Nobel prize for their theoretical prediction.
1973 –
Frank Anthony Wilczek discover the quark asymptotic freedom in the theory of strong interactions; receives the
Lorentz Medal in 2002, and the Nobel Prize in Physics in 2004 for his discovery and his subsequent contributions to
quantum chromodynamics.[8]
1974 –
Burton Richter and
Samuel Ting: Charm quarks are produced almost simultaneously by two teams in November 1974 (see
November Revolution) — one at
SLAC under Burton Richter, and one at
Brookhaven National Laboratory under Samuel Ting. The charm quarks are observed bound with charm
antiquarks in
mesons. The two discovering parties independently assign the discovered meson two different symbols, J and ψ; thus, it becomes formally known as the
J/ψ meson. The discovery finally convinces the physics community of the quark model's validity.
1975 –
Martin Lewis Perl, with his colleagues at the
SLAC–
LBL group, detects the
tau in a series of experiments between 1974 and 1977.
1977 –
Leon Lederman observes the
bottom quark with his team at
Fermilab.[9] This discovery is a strong indicator of the
top quark's existence: without the top quark, the bottom quark would be without a partner that is required by the mathematics of the theory.
1995 – The
top quark is finally observed by a team at
Fermilab after an 18-year search.[9] It has a mass much greater than had been previously expected — almost as great as a gold atom.
The timeline of particle physics lists the sequence of particle physics theories and discoveries in chronological order. The most modern developments follow the scientific development of the discipline of
particle physics.
1927 –
Charles Drummond Ellis (along with
James Chadwick and colleagues) finally establish clearly that the beta decay spectrum is in fact continuous and not discrete, posing a problem that will later be solved by theorizing (and later discovering) the existence of the
neutrino.
1964 –
François Englert,
Robert Brout,
Peter Higgs,
Gerald Guralnik,
C. R. Hagen, and
Tom Kibble postulate that a fundamental quantum field, now called the
Higgs field, permeates space and, by way of the
Higgs mechanism, provides mass to all the elementary subatomic particles that interact with it. While the Higgs field is postulated to confer mass on quarks and leptons, it represents only a tiny portion of the masses of other subatomic particles, such as protons and neutrons. In these, gluons that bind quarks together confer most of the particle mass. The result is obtained independently by three groups: François Englert and Robert Brout; Peter Higgs, working from the ideas of Philip Anderson; and Gerald Guralnik, C. R. Hagen, and Tom Kibble.[1][2][3][4][5][6][7]
1964 –
Sheldon Glashow and
James Bjorken predict the existence of the charm quark. The addition is proposed because it allows for a better description of the
weak interaction (the mechanism that allows quarks and other particles to decay), equalizes the number of known
quarks with the number of known
leptons, and implies a mass formula that correctly reproduced the masses of the known
mesons.
1968 –
Stanford University:
Deep inelastic scattering experiments at the
Stanford Linear Accelerator Center (SLAC) show that the
proton contains much smaller, point-like objects and is therefore not an elementary particle. Physicists at the time are reluctant to identify these objects with
quarks, instead calling them partons — a term coined by Richard Feynman. The objects that are observed at SLAC will later be identified as
up and
down quarks. Nevertheless, "parton" remains in use as a collective term for the constituents of
hadrons (quarks,
antiquarks, and
gluons). The existence of the
strange quark is indirectly validated by the SLAC's scattering experiments: not only is it a necessary component of Gell-Mann and Zweig's three-quark model, but it provides an explanation for the
kaon (K) and
pion (π) hadrons discovered in cosmic rays in 1947.
1970 – Glashow,
John Iliopoulos and
Luciano Maiani predict the charmed quark that is subsequently found experimentally and share a Nobel prize for their theoretical prediction.
1973 –
Frank Anthony Wilczek discover the quark asymptotic freedom in the theory of strong interactions; receives the
Lorentz Medal in 2002, and the Nobel Prize in Physics in 2004 for his discovery and his subsequent contributions to
quantum chromodynamics.[8]
1974 –
Burton Richter and
Samuel Ting: Charm quarks are produced almost simultaneously by two teams in November 1974 (see
November Revolution) — one at
SLAC under Burton Richter, and one at
Brookhaven National Laboratory under Samuel Ting. The charm quarks are observed bound with charm
antiquarks in
mesons. The two discovering parties independently assign the discovered meson two different symbols, J and ψ; thus, it becomes formally known as the
J/ψ meson. The discovery finally convinces the physics community of the quark model's validity.
1975 –
Martin Lewis Perl, with his colleagues at the
SLAC–
LBL group, detects the
tau in a series of experiments between 1974 and 1977.
1977 –
Leon Lederman observes the
bottom quark with his team at
Fermilab.[9] This discovery is a strong indicator of the
top quark's existence: without the top quark, the bottom quark would be without a partner that is required by the mathematics of the theory.
1995 – The
top quark is finally observed by a team at
Fermilab after an 18-year search.[9] It has a mass much greater than had been previously expected — almost as great as a gold atom.