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Re: how many "forces" (or better, interactions)?



Jack: I'm only trying to argue for a new (fifth) interaction beyond
the usual four. I called it the "Higgs" interaction for lack of a
better term, but I thought I made it clear in my post that I am not
arguing for any particular model. Don't you have anything better
to do? -dan

Hi Dan Schroeder--
I do not share your enthusiasm for the Higgs model. You writeMessage-Id: <01IQ4G0DHXR68ZL1RK@cc.WEBER.EDU>
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I see. Am I to infer that phenomena at higher energies are not
well modeled by the four interactions known, and that the Higgs
particle's existence is accurately inferred from those higher
energy data? You don't say exactly that.

Leigh

I'm sorry, perhaps I didn't answer your question as directly
as I should have. The phenomena that require the Higgs interaction
are the very existence of nonzero masses for most of the quarks
and leptons as well as the W and Z. Also the various "mixing"
angles which allow, for instance, a strange quark to decay to
an up quark. These phenomena are well modeled by various
terms in the standard model Lagrangian, which I suppose
are somewhat analogous to the old Fermi theory of beta
decay. But just as the Fermi theory was silent on higher-energy
phenomena (like W and Z resonances), so also we expect there
to be a rich set of Higgs interaction phenomena at higher energies
which are not predicted by the "minimal" standard model.
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The Higgs, in the standard model, is a device for breaking the
symmetry of a highly symmetric Lagrangian with all of the particles
being massless. The Higgs mechanism purports to give mass to all
of the particles (except the photon), and breaks the symmetry. It does
not, repeat NOT, predict the values of the particle masses. Nor is there
any specific experimental evidence for the existence of the Higgs.
As an alternative to the Higgs mechanism for the W-Z masses, one
can imagine a bootstrap scheme where the self-interactions of the W-Z's,
and the interaction of the W-Z's with the top quark, give rise to the
W-Z masses and also to a "Higgs" resonance in the WW channel. The
spins of the particles make the calculations quite difficult, an it is
not at all clear that a doable calculation would be free from ambiguity.
The main difficulty with the standard model (it's only a model,
as Weinberg keeps insisting) is that even if a "Higgs" is found, that
will not demonstrate that the "Higgs model" is correct.
The crucial experiments today are those that are attempting to
measure the W-W and W-Z interaction and the magnetic and quadrupole moments
of the W's. These appear to be unambiguously predicted by the standard
model (but that is not the only model that makes the predictions).
Regards,
Jack