"Antidown" redirects here. For the EP by Burial, see Antidawn.
Down quark
Composition
elementary particle
Statistics
fermionic
Family
quark
Generation
first
Interactions
strong, weak, electromagnetic, gravity
Symbol
d
Antiparticle
down antiquark ( d )
Theorized
Murray Gell-Mann (1964) George Zweig (1964)
Discovered
SLAC (1968)
Mass
4.7+0.5 −0.3 MeV/c2[1]
Decays into
stable or up quark + electron + electron antineutrino
Electric charge
−1/3e
Color charge
Yes
Spin
1/2ħ
Weak isospin
LH: −1/2, RH: 0
Weak hypercharge
LH: +1/3, RH: −2/3
The down quark (symbol: d) is a type of elementary particle, and a major constituent of matter. The down quark is the second-lightest of all quarks, and combines with other quarks to form composite particles called hadrons. Down quarks are most commonly found in atomic nuclei, where it combines with up quarks to form protons and neutrons. The proton is made of one down quark with two up quarks, and the neutron is made up of two down quarks with one up quark. Because they are found in every single known atom, down quarks are present in all everyday matter that we interact with.
The down quark is part of the first generation of matter, has an electric charge of −1/3e and a bare mass of 4.7+0.5 −0.3 MeV/c2.[1] Like all quarks, the down quark is an elementary fermion with spin 1/2, and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the down quark is the down antiquark (sometimes called antidown quark or simply antidown), which differs from it only in that some of its properties have equal magnitude but opposite sign.
Its existence (along with that of the up and strange quarks) was postulated in 1964 by Murray Gell-Mann and George Zweig to explain the Eightfold Way classification scheme of hadrons. The down quark was first observed by experiments at the Stanford Linear Accelerator Center in 1968.
^ ab
M. Tanabashi et al. (Particle Data Group) (2018). "Review of Particle Physics". Physical Review D. 98 (3): 1–708. Bibcode:2018PhRvD..98c0001T. doi:10.1103/PhysRevD.98.030001. hdl:10044/1/68623. PMID 10020536.
The downquark (symbol: d) is a type of elementary particle, and a major constituent of matter. The downquark is the second-lightest of all quarks, and...
observable matter is composed of up quarks, downquarks and electrons. Owing to a phenomenon known as color confinement, quarks are never found in isolation;...
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...
matter. It, along with the downquark, forms the neutrons (one up quark, two downquarks) and protons (two up quarks, one downquark) of atomic nuclei. It...
bottom quark, beauty quark, or b quark, is an elementary particle of the third generation. It is a heavy quark with a charge of −1/3 e. All quarks are described...
The top quark, sometimes also referred to as the truth quark, (symbol: t) is the most massive of all observed elementary particles. It derives its mass...
the first fermion generation. The first generation consists of up and downquarks which form protons and neutrons, and electrons and electron neutrinos...
the individual neutrons break down into their constituent quarks (up quarks and downquarks), forming what is known as quark matter. This conversion may...
The charm quark, charmed quark, or c quark is an elementary particle found in composite subatomic particles called hadrons such as the J/psi meson and...
In particle physics, the quark model is a classification scheme for hadrons in terms of their valence quarks—the quarks and antiquarks that give rise to...
mass). Neutrons are made up of one up and two downquarks, while protons are made of two up and one downquark. Since the other common elementary particles...
valence quarks, and together with neutrons are now classified as hadrons. Protons are composed of two up quarks of charge +2/3e each, and one downquark of...
particle physics, isospin (I) is a quantum number related to the up- and downquark content of the particle. Isospin is also known as isobaric spin or isotopic...
up quark has T3 = ++1/2 and the downquark has T3 = −+1/2. A quark never decays through the weak interaction into a quark of the same T3: Quarks with...
their corresponding antiquarks replace quarks. For example, a proton is made of two up quarks and one downquark; and its corresponding antiparticle, the...
first-generation quarks. In the quark model, an up quark and an anti-downquark make up a π+ , whereas a downquark and an anti-up quark make up the π−...
example, a neutron, composed of two downquarks and an up quark, decays to a proton composed of a downquark and two up quarks. Electron capture is sometimes...
(usually three quarks) and mesons, made of an even number of quarks (usually two quarks: one quark and one antiquark). Protons and neutrons (which make the...
up quark and two downquarks. Quarks are held together by the strong force, or equivalently, by gluons, which mediate the strong force at the quark level...
equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles,...
three positively charged quarks are called "up-type quarks" while the three negatively charged quarks are called "down-type quarks". Leptons do not interact...
less. A proton is made of two up quarks and one downquark, while the neutron is made of two downquarks and one up quark. These commonly bind together into...
built out of up and downquarks), and with non-strange quark matter, which is a quark liquid that contains only up and downquarks. At high enough density...
of a W− boson from one of the downquarks hidden within the neutron, thereby converting the downquark into an up quark and consequently the neutron into...
of protons, save for the difference in quark composition with a downquark in the neutron replacing an up quark in the proton. The neutron magnetic moment...
up and downquarks. Quark matter is a condensed form of matter composed entirely of quarks. When quark matter does not contain strange quarks, it is sometimes...
family of subatomic hadron particles containing one up quark, one downquark, and a third quark from a higher flavour generation, in a combination where...
particles called quarks. The two most common types of quarks are up quarks, which have a charge of +2⁄3, and downquarks, with a −1⁄3 charge. Quarks arrange themselves...
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