Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.
Well, how do we know that the proton has a fm? When hitting it with a charged particle with a Compton wavelength in the order of 1 fm in a scatter experiment, we start to see a formfactor, e.g. the particle doesn't see the full charge any more.
LEP II had about 100 GeV/c^2 per electron, therefore a Compton wavelength of about 10^(-17)m, and there was not the slightest sign of substructure, we still see absolutely the full structure and one would likely expect already small signs of a formfactor with a somewhat bigger wavelength than the electron size.

I don't know what measurement exactly provides the best measurement, could be a precision measurement of the B sector or whatever, but that's it pretty much.

Der Amerikaner ist die Orchidee unter den Menschen
Volker Pispers

by Martin (weiser.mensch(at)googlemail.com) on Fri Feb 22nd, 2008 at 05:17:09 PM EST
[ Parent ]
There's more than one LEP? that's scary ;-)

Any idiot can face a crisis - it's day to day living that wears you out.
by ceebs (ceebs (at) eurotrib (dot) com) on Fri Feb 22nd, 2008 at 05:32:24 PM EST
[ Parent ]


Occasional Series