From: Michael S. Lorrey (mike@lorrey.com)
Date: Tue Aug 17 1999 - 08:22:27 MDT
John Clark wrote:
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Joseph C Fineman <jcf@world.std.com> Wrote:
>
> >Antineutrinos exist in any case.
>
> Yes, they were actually discovered experimentally before neutrinos were.
>
> >They are distinguished from neutrinos by their helicity (direction
> >of spin relative to their direction of motion). When a neutron decays,
> >for example, it yields a proton, an electron, and an antineutrino.
> >However, it seems to me that if neutrinos have rest mass, this
> >distinction must in principle lapse, since you can then choose a
> >frame of reference in which the helicity is reversed.
>
> You can't turn a right hand glove into a left one in any frame of
> reference, at least not if you stay in 3 dimensions; you'd have to
> flip it around in the fourth spatial dimension. Besides, the two
> particles act differently. A antineutrino is absorbed (rarely) by a
> proton which turns into a neutron and a positron (also called a
> anti electron), a neutrino is absorbed (rarely) by a neutron which
> turns into a proton and a electron.
Which if you put on a Feynman chart are the same reaction when you
reverse the time component. In reverse, the neutrino will seem to be
absorbed by the proton while emitting a neutron and an anti-electron
(the eletron going backwards in time).
Mike Lorrey
This archive was generated by hypermail 2.1.5 : Fri Nov 01 2002 - 15:04:47 MST