down quark


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down quark

[′dau̇n ‚kwärk]
(particle physics)
A quark with an electric charge of -⅓, baryon number of ⅓, and 0 strangeness and charm.
References in periodicals archive ?
The ground state up quark incompletely annihilates with the ground state anti down quark to form a positron, [u.
If the down quark in the disintegrated electron quark-antiquark pair and the antidown quark in the disintegrated positron quark-antiquark pair are excited, then the annihilations produce leptons [[tau].
As shown in Figure 6a, the excited down quark in the neutron can incompletely annihilate with the ground state antiup quark into a negative tau particle [[tau].
Figure 1 is a schematic diagram that shows formations of four generations of leptons from annihilations of up and down quarks and antiquarks with one excited quantum state for each of them.
For instance, a proton is composed by two up quarks and one down quarks (uud); a neutron is composed by one up quark and two down quarks (udd); a pion, [[pi].
If things go well, in the next several years, the up and down quarks may finally weigh in, van Kolck says.
A neutron, which also has a spin of 1/2, consists of two down quarks and one up quark.
It's also possible that not only up and down quarks but also the other varieties of quarks--strange, charm, bottom and top (SN: 7/1/95, p.
Thus, a newly formed pulsar could shed additional energy by turning some of its up and down quarks into strange ones.
This quark matter would include the so-called up and down quarks of which protons and neutrons are made and also "strange" quarks, which are heavier and not found in ordinary matter.
A theory developed in 1977 suggests that lambdas would readily fuse together into 6-quark particles called H's, each composed of two strange, two up, and two down quarks.
The existence of compact stars containing strange matter hinges on the hypothesis that a quark nugget consisting of roughly equal proportions of up, down, and strange quarks may be more stable than an ordinary atomic nucleus, which contains only up and down quarks (SN: 3/4/89, p.