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The question I want answered is not why a neutron takes so long to decay - that seems understandable as it's mitigated by the weak force - but why is that time of ~14.63 minutes the actual time it is? When the W- boson decays into an electron and antineutrino it happens millions of times faster than the life of the neutron itself. What makes that trigger point happen when it does?
The question I want answered is not why a neutron takes so long to decay - that seems understandable as it's mitigated by the weak force - but why is that time of ~14.63 minutes the actual time it is? When the W- boson decays into an electron and antineutrino it happens millions of times faster than the life of the neutron itself. What makes that trigger point happen when it does?
Nobody knows
Here's a question I was always curious to hear a good intuitive explanation for -- Why does a neutron star not decay, as it is composed of neutrons, and free neutrons should decay in 15 minutes? Is it because the neutrons are in an energetic "well" and to decay out would actually require energy? In collapsing under gravity to neutron degeneracy, did the neutrons say, radiate away their ability to decay any more?
So you can control neutrons with magnetic fields??
Earlier quoted context omitted.
Nobody knows
is the annoying answer "if it were really that much shorter we probably wouldn't exist"?
"Magnetic fields at the bottom of the bottle prevented the neutrons from touching the surface," So you can control neutrons with magnetic fields??
The question I want answered is not why a neutron takes so long to decay - that seems understandable as it's mitigated by the weak force - but why is that time of ~14.63 minutes the actual time it is? When the W- boson decays into an electron and antineutrino it happens millions of times faster than the life of the neutron itself. What makes that trigger point happen when it does?
Fermi's Golden Rule in principle allows you to calculate the decay rate. In practice we dont know how to calculate all the relevant quantities since QCD is hard.
Earlier quoted context omitted.
From skimming the review paper from OP (the "source:" in the caption on that error-bar chart), the neutrons in the beam experiments are thermalized, to a mean velocity of ~2,200 m/s. So, slower than 1e-5 c. https://doi.org/10.3390/atoms6040070 (Thermal meaning the neutrons scatter lots of times against atoms in a solid material, until they reach thermal equilibrium. ~km/s is a typical Boltzmann velocity for atom-size…
How does the scattering affect the neutrons? When do we start the clock for their lifetime anyway? It sounds like they could absorb + reemit sometimes when being scattered.
There is probably a Nobel for whoever solves this.
Capturing some from a beam into a magnetic trap seems like a good start.
It seems like the difference in lifetimes demands new physics. If the magnetically trapped neutron lifetimes match Standard Model predictions, then something involved in getting them into the beam must be changing them, or selecting out longer-lived individuals, both of which seem bonkers. There is probably a Nobel for whoever solves this. Capturing some from a beam into a magnetic trap seems like a good start.
If the discrepancy persists, then there really will be a problem.
There is plenty of theoretical speculation, especially in the last couple of years, about what such a discrepancy, if true, might mean. Again, it would be a real surprise, but if neutrons have another decay pathway other than the known one, then the bottle method measures the total decay rate, while the beam method measures the electron/beta-decay rate only.
The emerging state of the art, should this discrepancy persist, will become experiments that measure both channels simultaneously.