What is beta decay in terms of quarks?

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Answer 1 · 2016-06-06T02:03:03

In β-decay, a quark decays into another type of quark, releasing a β particle and a neutrino.

Protons and neutrons consist of quarks.

A proton consists of two up quarks and a down quark (#"p = uud"#).

In positron (#β^+#) decay, an up quark changes to a down quark, with the release of a positron and a neutrino.

#"u → d" color(white)(l)+ β^+ + ν#

The overall result us that a proton becomes a neutron:

#"p → n"color(white)(l) + β^+ + ν#

A neutron consists of two down quarks and a up quark (#"n = ddu"#).

In beta (#β^"-"#) decay, a down quark changes to an up quark, with the release of an electron (#β^"-"#) and an antineutrino.

#"d → u"color(white)(l) + β^"-" + bar(ν)#

The overall result us that a neutron becomes a proton:

#"n → p"color(white)(l) + β^"-" + bar(ν)#

In pictures, β-decay looks like this:

β decay
(from schoolphysics.co.uk)