up quark

American  

noun

Physics.

1. the quark having electric charge 2/3 times the elementary charge and strangeness and charm equal to 0.

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up quark Scientific  

/ ŭp /

1. 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.

2. See Table at subatomic particle

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Etymology

Origin of up quark

First recorded in 1975–80

Example Sentences

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

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

In the new particle, the up quark circulates around the two heavy charm quarks at the center.

From New York Times • Jul. 6, 2017

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

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