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)