rjnoe@ihlts.UUCP (06/10/83)
I heard a very brief mention on the radio not very long ago that European researchers (at CERN?) had confirmed discovery of the Z0 particle. I am not terribly well informed when it comes to this specific inmate of the subatomic zoo, but I recall hearing predictions quite some time ago that if this particle were discovered to actually exist, much theory of atomic structure would be "proven" and it would lead to a unification of the weak and strong nuclear forces with the electromagnetic force. I think the reason it took so long to discover is that it is VERY massive. Does anyone know anything else on the topic? If so, please post it. Roger Noe ...ihnp4!ihlts!rjnoe
yin@megatest.UUCP (06/15/83)
#R:ihlts:-14600:megatest:10300001:000:2178
megatest!yin Jun 14 19:13:00 1983
The Z0 particle is the neutral intermediate vector boson. It, along with
the W+ and W- particles (the charged IVB's), are believed to be mediators
of the weak force (one example of the weak force in action is beta decay).
The Glashow-Salam-Weinberg (GSW) theory of electroweak interactions, whose
originators won the Nobel Prize back in 1980(?), along with other theories,
predicts the existence of Z0, W+ and W- and gives some of their expected
physical characteristics. By considerations of beta decay amplitudes and
widths, a lower bound of 30 Gev can be put on the mass of these particles.
If the additional constraints of the GSW theory are considered as well,
then the predicted mass of these particles is -
M(Z0) = 90 Gev
M(W+) = M(W-) = 80 Gev
As you can see, these are very massive particles. Their large mass accounts
for the weakness of the weak force as well as for their rare appearances,
which had to wait for the recent generation of particle accelerators to come
on line. The existence of the Z0 particle is a major step in the verification
of these electroweak theories.
The GSW theory is a gauge field theory that attempts to unify the weak force
and the electromagnetic force, much the same way that quantum electrodynamics
(QED) unified quantum mechanics and electrodynamics. It is a major step
toward grand unified field theories, which would include the strong force.
I do not believe that the existence of Z0 helps the grand unified theories
as much as it does the electroweak theories, beyond the verification gained
because grand unified theories tend to build on electroweak theories. An
interesting prediction of the grand unified theories is that hadron number
should not always be conserved. Since protons are known to have a lifetime
>10^30 years, it is necessary to postulate the existence of a proton decay
mediator with extremely large mass, i.e. the X particle where -
M(X) = 10^14 to 10^15 Gev
It will be a while before a particle accelerator exists which can produce
something that massive.
yin shih, megatest corp (...!lbl-csam!megatest!yin)rh@mit-eddi.UUCP (Randy Haskins) (06/26/83)
How plausible is a grand unified field theory? I know that the weak-electro theory has been doing well, and the Z0 particles makes it almost iron-clad. But the strong force? From what I learned in an intro-to-quantum course, we can solve the electro-magnetic interactions explicitly only because the Fine Structure Constant is less than 1 (~ 1/137). The weak force just happens to be obviously tied to E&M. But the strong force has a constant (analogous to the FSC) that is quite a bit greater than 1 (I don't remember what it is). And don't even talk about tying in gravity. Nobody knows what a 'graviton' looks like. Anybody care to respond? --Randy