- #1
nonequilibrium
- 1,439
- 2
Hello,
I'm taking a particle physics class and we're using Griffiths' book "Introduction to Elementary Particles". I was reading in it but two statements in it (on the same page, for reference p33 in the second edition) struck me as weird, and as I would greatly appreciate if anyone could clarify them for me:
Statement A
(regarding the non-decay of protons)
Statement B
(after introducing the law of conservation of baryon number)
* this last remark is applicable to any particle and isn't proton-specific
I'm taking a particle physics class and we're using Griffiths' book "Introduction to Elementary Particles". I was reading in it but two statements in it (on the same page, for reference p33 in the second edition) struck me as weird, and as I would greatly appreciate if anyone could clarify them for me:
Statement A
(regarding the non-decay of protons)
We know free neutrons have a finite lifetime, but they are stable in nuclei (due to the Pauli principle, if I understand correctly). Why wouldn't the same logic apply to protons (well I suppose I get why it doesn't work for hydrogen)?Needless to say, it would be unpleasant for us if this reaction were common (all atoms would disintegrate) [...]
Statement B
(after introducing the law of conservation of baryon number)
But if that is the logic, isn't it possible to just send a very high energy photon onto a proton to get a neutron (to make up for the relatively low rest mass of the proton)? Or for example can't a really fast moving proton (= high kinetic energy) decay into another (necessarily more massive) baryon (with by-products, to make the mechanical conservation laws work out)? Then again that wouldn't make sense for any particle, from a relativistic stand point (i.e. the decay can't happen from the proton's reference frame, not having the kinetic energy), however it seems there is nothing that forbids the decay from happening in the certain reference frame in which the proton is going near the speed of light(?)*But the proton, as the lightest baryon, has nowhere to go; conservation of baryon number guarantees its absolute stability.
* this last remark is applicable to any particle and isn't proton-specific