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So a free neutron will decay into a proton and an electron. This already confuses me because the only difference between the nucleons is an up quark (uud vs ddd

by jmyeet 5y ago

So a free neutron will decay into a proton and an electron. This already confuses me because the only difference between the nucleons is an up quark (uud vs ddd) and an electron an a lepton is a fundamental particle. But an electron in an atom won’t merge with a proton to form a neutron. There seems to be some hand waving here around the strong nuclear force and zero energy state that I don’t really understand. But in a neutron star the forces are so great that I believe this can happen (or how else does neutronium form?). And now we see an antiproton can annihilate a proton. Doesn’t this have the same zero energy problem? Can someone ELI5?

ladams 5y ago
Worth noting that a neutron decays into a proton, an electron, AND an electron anti-neutrino, so that lepton number is conserved (electron is +1 and anti-neutrino is -1). This interaction conserves charge and baryon number as well.
myself248 5y ago
ITYM ELI27....
- vba616 5y ago
  ELITTCCCAHEM Explain-like-I-took-three-college-calc-courses-and-hated-every-minute
deleted 5y ago
[deleted]
vikingerik 5y ago
Electrons in an atom do merge with a proton to form a neutron. https://en.wikipedia.org/wiki/Electron_capture https://en.wikipedia.org/wiki/Electron_capture
- deleted 5y ago
  [deleted]
maxnoe 5y ago
> So a free neutron will decay into a proton and an electron. This already confuses me because the only difference between the nucleons is an up quark (uud vs udd) and an electron an a lepton is a fundamental particle Conversion between different Quarks are mediated ny the weak force. The associated particles of the weak force are three bosons: W+, W- , and Z0. (Positively, negatively and neutrally charged). To convert a neutron into a proton, you convert an up into a down quark. This is done by emitting a W-, carrying away the negative charge. The W- then decays into an electron and an anti-electron neutrino. As noted by parent commenter, the same process can and does happen in reverse, just not for free protons. It happens in Proton rich nuclei and for some is there predominant decay channel, see an table of nuclides: https://en.m.wikipedia.org/wiki/Table_of_nuclides https://en.m.wikipedia.org/wiki/Table_of_nuclides The nuclides above the stable line are Proton rich and thus decay by either electron capture or positron emission.

by jmyeet 5y ago

ladams 5y ago

Worth noting that a neutron decays into a proton, an electron, AND an electron anti-neutrino, so that lepton number is conserved (electron is +1 and anti-neutrino is -1). This interaction conserves charge and baryon number as well.

myself248 5y ago

ITYM ELI27....

vba616 5y ago
ELITTCCCAHEM Explain-like-I-took-three-college-calc-courses-and-hated-every-minute

deleted 5y ago

[deleted]

vikingerik 5y ago

Electrons in an atom do merge with a proton to form a neutron. https://en.wikipedia.org/wiki/Electron_capture https://en.wikipedia.org/wiki/Electron_capture

deleted 5y ago
[deleted]

maxnoe 5y ago

> So a free neutron will decay into a proton and an electron. This already confuses me because the only difference between the nucleons is an up quark (uud vs udd) and an electron an a lepton is a fundamental particle Conversion between different Quarks are mediated ny the weak force. The associated particles of the weak force are three bosons: W+, W- , and Z0. (Positively, negatively and neutrally charged). To convert a neutron into a proton, you convert an up into a down quark. This is done by emitting a W-, carrying away the negative charge. The W- then decays into an electron and an anti-electron neutrino. As noted by parent commenter, the same process can and does happen in reverse, just not for free protons. It happens in Proton rich nuclei and for some is there predominant decay channel, see an table of nuclides: https://en.m.wikipedia.org/wiki/Table_of_nuclides https://en.m.wikipedia.org/wiki/Table_of_nuclides The nuclides above the stable line are Proton rich and thus decay by either electron capture or positron emission.