The down quark
[d.sub.0] and the antidown quark [[bar.d].sub.0] completely annihilate into a muon neutrino [v.sub.[mu]] or an antimuon neutrino [[bar.v].sub.u].
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].sup.+], is composed by one up quark and one down antiquark (u[bar.d]); a charmed sigma, [[SIGMA].sup.++.sub.c], is composed by two up quarks and one charm quark (uu[bar.c]); and so on.
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.
Thus, a newly formed pulsar could shed additional energy by turning some of its up and down quarks
into strange ones.
The quark matter would consist not only of the up and down quarks
that make up protons and neutrons, but also strange quarks, which aren't found in ordinary matter.
Protons and neutrons are made of up and down quarks
, the two first-generation quarks.
A neutron (see ) has one Up quark (with the charge of + 2/3 x 1.606 x [10.sup.19] C) and two Down quarks
(each with the charge of -1/3 x 1.606 x [10.sup.19] C), while an antineutron has one anti Up quark (with the charge of -2/3 x 1.606 x [10.sup.19] C) and two anti Down quarks
(each with the charge of + 1/3 x 1.606 x x [10.sup.19] C).
Ordinary matter, such as protons and neutrons, contains only up quarks and down quarks
, whereas the sigma-bs each contain a bottom quark and either a pair of up quarks or a pair of down quarks
The quarks that behaved as expected were down quarks
, and the one that didn't was an up quark.
Ups and downs Landmark particle-accelerator experiments provided physicists with long-sought data needed to better understand up and down quarks
, the building blocks of ordinary matter (163: 227 *).
There are two common types of quarks known as the up and down quarks
. A proton is made up of one down and two up quarks; the neutron reverses those numbers.