Thread #59418 Message #1931587

Posted By: Rapparee

09-Jan-07 - 01:58 PM

Thread Name: BS: The Mother of all BS threads

Subject: RE: BS: The Mother of all BS threads

Fermilab may be close to finding Higgs particles (Higgs boson) and the Higgs field:

In the GWS model, the spontaneous breakdown is brought about the introduction of an elementary scalar field. This leads to the prediction of (at least) an additional spin-zero particle, the Higgs boson. With the discovery of the W± and Z0 bosons at the CERN pp collider, and the top quark at the FERMILAB, only the Higgs boson

remains to be discovered to complete the particle content of the GWS electroweak theory. It should be pointed out that no elementary spin-zero particles have ever been found. In fact, the ad hoc introduction of these considered by many theorists to be an

unpleasant feature of the standard model.

The problem is the instability of the scalar particles masses under radiative corrections. For example, one-loop radiative corrections to these diverge quadratically, leading to corrections of the form:

δm2 = O(α/π)2

where is a cut-off parameter representing the scale of the theory and

α = e2/hc

≈ 1

is the fine structure constant. The parameter may be the Grand Unified Theory (GUT) scale O(1015GeV/c2), or the Plank scale O(1019GeV/c2) if we believe there is no new physics all the way up to the scale associated with quantum gravity. On the other hand, we know that for the scalar self-couplings to be sensibly treated within perturbation theory, the scalar mass

m2 6 O(m2

W/α) ∼ 1TeV/c2

In other words, either the Higgs sector is strongly interacting, or δm2 ≫,m2.

Such theories (where δm2 ≫,m2) have been technically referred to as

"unnatural", because the parameters have to be tuned with unusual precision in order to preserve the lightness of the Higgs mass compared to the GUT scale ˜O(1TeV/c2).

One possible solution to the problem of naturalness is to imagine that the quarks, leptons and gauge bosons are all composites with associated scale ˜O(1TeV/c2). While these solve the problem at present energies, it does not really represent a solution as we could ask the same questions of any underlying theory. Moreover, it would be difficult to understand why the gauge principle seems to work so well at least up to this point.