🚀 go-pugleaf

In article <1992Nov6.020022.29066@murdoch.acc.Virginia.EDU>, crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes...

>      How can one make definitive statements about GUT's *requiring*
>      new massive particles without there existing a tenable GUT?
>      After all, I am reasonably sure that there are infinite possible
>      theories that do not require new particles.  In fact, there are 
>      probably potential GUTs that do not even use the concept of particles.
>      I am not so confident as to the suitability nor the uniqueness of
>      our representations as you appear to be.

Every GUT in the standard panoply of GUT's requires new heavy particles.  
One of the nice things about the simplest GUT, SU(5), is that it requires 
no new fermions, just a few very heavy IVBs to mediate lepton-quark 
transformations.  For more complicated choices of gauge group you start 
getting all sorts of wierd "extraneous" particles, none of which have ever 
been seen.  

The speculation that some future hypothetical "GUT" might not even use the 
notion of particles is is totally groundless, and not useful.  Anything
is possible.  So what?  You have to use the clues you have.  Every theory
we try to build which extends the SM in what seems to be a natural way
inevitably includes additional particles.  Sometimes we discover these 
particles, and someone becomes famous.  More often, they just fade away.

And what exactly do you mean by "tenable"?  There are plenty of GUT choices
which are consistent with all the available data.  (Of course, there is 
little available data.) 

-Scott
--------------------
Scott I. Chase			"It is not a simple life to be a single cell,
SICHASE@CSA2.LBL.GOV		 although I have no right to say so, having
				 been a single cell so long ago myself that I 
				 have no memory at all of that stage of my 
				 life." - Lewis Thomas