This article provides insufficient context for those unfamiliar with the subject.(January 2023) |
When embedded in an atomic nucleus, neutrons are (usually) stable particles. Outside the nucleus, free neutrons are unstable and have a mean lifetime of 877.75+0.50
−0.44 s[1] or 879.6±0.8 s[2] (about 14 min and 37.75 s or 39.6 s, respectively). Therefore, the half-life for this process (which differs from the mean lifetime by a factor of ln(2) ≈ 0.693) is 611±1 s (about 10 min, 11 s).[3][4]
The beta decay of the neutron described in this article can be notated at four slightly different levels of detail, as shown in four layers of Feynman diagrams in a section below.
The hard-to-observe
W−
quickly decays into an electron and its matching antineutrino. The subatomic reaction shown immediately above depicts the process as it was first understood, in the first half of the 20th century. The boson (
W−
) vanished so quickly that it was not detected until much later.
Later, beta decay was understood to occur by the emission of a weak boson (
W±
), sometimes called a charged weak current. Beta decay specifically involves the emission of a
W−
boson from one of the down quarks hidden within the neutron, thereby converting the down quark into an up quark and consequently the neutron into a proton. The following diagram gives a summary sketch of the beta decay process according to the present level of understanding.
3 quark composite neutron ( n0 ) |
3 quark composite proton ( p+ ) |
||||||
︷ | ︷ | ||||||
( u d d ) |
→ | ( u d u ) |
+ | W− |
|||
⤷ | e− |
+ ν e | |||||
︸ | |||||||
subsequent W− decay |
For diagrams at several levels of detail, see § Decay process, below.
Gonzalez-2021
was invoked but never defined (see the help page).PDG-2020-n-life
was invoked but never defined (see the help page).Beringer-etal-2012-PDG-010001
was invoked but never defined (see the help page).PDG-2007-baryons-LPL
was invoked but never defined (see the help page).