down quark

American  

noun

Physics.

1. the quark having electric charge −1/3 times the elementary charge, with strangeness, charm, and other quark quantum numbers equal to 0.

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Etymology

Origin of down quark

First recorded in 1975–80

Example Sentences

While a proton contains two up quarks and one down quark, the Ξcc⁺ replaces the up quarks with heavier charm quarks.

From Science Daily • Mar. 19, 2026

Normal protons have two "up" quarks and one "down" quark.

From Barron's • Mar. 17, 2026

For instance, the electron has heavier versions called muons and taus, the up quark has heavier relatives named charm and top quarks, and the down quark is followed by strange and beauty quarks.

From Scientific American • Nov. 14, 2022

Dr. Spradlin said he and his colleagues are searching the same data that revealed the Xi-cc++ for the baryon with two charm quarks and one down quark.

From New York Times • Jul. 6, 2017

A proton contains two up quarks and one down quark; a neutron contains two down and one up.

From "A Brief History of Time: And Other Essays" by Stephen Hawking