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From: JGA%MIT-MC@sri-unix.UUCP
Newsgroups: net.physics
Subject: Massive fermions - minor quibble.
Message-ID: <13411@sri-arpa.UUCP>
Date: Mon, 7-Nov-83 13:18:00 EST
Article-I.D.: sri-arpa.13411
Posted: Mon Nov  7 13:18:00 1983
Date-Received: Wed, 9-Nov-83 07:39:59 EST
Lines: 38

From:  John G. Aspinall <JGA @ MIT-MC>

    --------
    Date: 2 Nov 83 5:19:17-PST (Wed)
    From: ihnp4!houxm!houxz!halle1 at Ucb-Vax
    To:   physics at Sri-Unix
    Re:   Massive fermions - minor quibble.
    Article-I.D.: houxz.568

    Obviously, massive was meant to be massless.  However, protons and
    neutrons are not fermions, massive or otherwise.  They are BOSONS.
    --------

Oh dear.  Perhaps we'd better make some definitions.

Bosons : - Obey Bose-Einstein statistics
         - Integral spin
         - Do NOT obey an exclusion principle

Fermions : - Obey Bose-Einstein statistics
           - Half-integral spin
           - Do obey an exclusion principle

Using the spin property and the type of interaction we can also classify

Leptons : Half-integral spin, electro-weak interaction
Mesons  : Integral spin, strong and other interactions
Baryons : Half-integral spin, strong and other interactions

(This is not all-inclusive, for instance the photon doesn't fit in any of these.)

There are "shells" and energy levels in nuclear structure, just as there are
in atomic structure.  Strong evidence of an exclusion principle at work.
Evidence of shell structure in nuclei includes gamma decay, large numbers of
nuclei with "magic number" N and Z - such as 20, 28, 50, 82, ground-state
angular momenta of nuclei, and hyperfine splitting of atomic spectra.

John Aspinall.