Re: [Phys-l] Question about Quarks and the Standard Model

[Jack Uretsky <jlu@hep.anl.gov>]

Hi Tony-
	Your questions are well-founded and illustrate some important 
misconceptions.
	The electromagnetic force comes in tow varieties, longitudinal and 
transverse.  The transverse forces are mediated by photons, which are 
two-component objects; one for each polarisation of the photon.  The 
longitudinalo component of the electromagnetic interaction - the coulomb 
force - are not thought of as carried by photons (which, after all, are 
transverse objects.)
	So your first question is moot; the photon is not important to the 
force felt by a proton from a nearby nucleon of similar charge.
	The quark view of matter is important to understanding the 
analyses being carried out today in connection with the LHC.  The current 
model is that a proton is a collection of three quarks (and losts of other 
"stuff") and the pp collisions in the LHC can be analyzed as collisions 
between the quarks in the colliding protons.  This type of analysis has 
worked well at Fermilab, and it remains to see how well it will work at 
the LHC.
			Regards,
				Jack

On Wed, 15 Oct 2008, Tony wrote:

> It has been many decades since I've thought in detail about quarks. As a
> high school teacher it has not been part of our state requirements. With the
> LHC coming on line and beginning to make headlines, I thought I'd teach a
> little about quarks and the standard model of particles when I get to
> electromagnetism. I beginning to write my notes out as a handouts with some
> web animations for my students ...(and I'm sure I'm over preparing.)
> However, I've been doing a smattering of reading around the net and have a
> few questions that I can't settle on a clear answer, perhaps someone can
> help.
>
> Question 1 ..with parts
> Protons feel the electromagnetic force due to an exchange of gauge bosons,
> (the photon). Why is this exchange particle important? Is the particle a
> signal to one protion that a like charge is near? And do we know what the
> proton, or any particle, does in response to receiving an "exchange
> particle?"
>
> Question 2
> A couple of sites I ran across, e.g. http://arxiv.org/abs/astro-ph/0606093 ,
> mentioned "Quark Stars." Are there any other applications/explanations using
> quarks? I trying to come up with tangible reasons for studying quarks that
> go beyond their cool strangeness?  ;-)
>
> Question 3
> Finally, I've been reading various edu sites on the net about quarks and the
> standard model. Does anyone have a recommendation of a intro level book or
> article(s) that I could read for more information?
>
> Question 4
> In Your Humble Opinion, what Is the most important "thing" high school
> students should remember about quarks and/or the "standard model?"
>
> Thanks in advance,
> -Tony

--
"Trust me.  I have a lot of experience at this."
		General Custer's unremembered message to his men,
		just before leading them into the Little Big Horn Valley