up quark
Americannoun
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A quark with a charge of +2/3. Its mass is approximately 10 times the electron mass and is the least mass of all quarks.
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See Table at subatomic particle
Etymology
Origin of up quark
First recorded in 1975–80
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
In 2017, the LHCb experiment announced that it had discovered a similar particle, made of two "charmed" quarks and one "up" quark.
From Barron's • Mar. 17, 2026
Physicists are also reassessing particle flavor, a quantum property that defines the species of fermion: up quark, down quark, electron, muon, and so on.
From Scientific American • Sep. 8, 2022
An experiment at CERN, within the behemoth Large Hadron Collider, counted more 300 Xi-cc++ baryons, each consisting of two heavy charm quarks and one up quark.
From New York Times • Jul. 6, 2017
A proton consists of two up quarks and one down quark, while a neutron contains one up quark and two down quarks.
From New York Times • Jul. 6, 2017
Each neutron is made of charged quarks: two down quarks that each carry a negative charge one-third as strong as an electron's; and an up quark that carries a two-thirds positive charge.
From Scientific American • Feb. 1, 2012
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
