Down quark

The down quark is a first-generation elementary particle with electric charge −⅓ of the elementary charge. It combines with up quarks to form protons and neutrons.

Quark: A quark is an elementary fermion that participates in the strong interaction and combines into hadrons. The down quark is one of six quark flavors.
Proton: The proton is a positively charged baryon made principally of two up quarks and one down quark. One down quark supplies part of the proton's quark content and charge.
Strange quark: The strange quark is a second-generation quark with electric charge −⅓ and greater mass than the down quark. It shares the down quark’s charge but is heavier and belongs to another generation.
Beta decay: Beta decay is radioactive decay in which a nucleus emits an electron or positron and a neutrino or antineutrino. In beta-minus decay, a neutron’s down quark changes into an up quark.
Up quark: The up quark is a first-generation elementary particle with electric charge +⅔ of the elementary charge. Together, two up quarks and one down quark form a proton.
Neutron: The neutron is a neutral baryon made principally of one up quark and two down quarks. Its two down quarks help give the neutron zero net electric charge.
Bottom quark: The bottom quark is a third-generation quark with electric charge −⅓ and much greater mass than the down quark. It shares the down quark’s charge while occupying the heaviest generation.
Weak interaction: The weak interaction is a fundamental force responsible for processes that change quark flavor and for certain radioactive decays. It permits down quarks to transform into up quarks.
Electric charge: Electric charge is a conserved property that determines how particles interact electromagnetically. Its fractional charge helps distinguish the down quark from the up quark.
Quantum chromodynamics: Quantum chromodynamics is the theory of the strong interaction between quarks and gluons. It describes the forces binding down quarks inside protons and neutrons.

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