On a scale of 1 to String, how speculative is this?

[BiGyElLoWhAt]

http://arxiv.org/abs/1503.09158
Is this a legitimite thing? I've never heard of 4th color charge or quark-lepton unification.

 

[marcus]

Just for a little extra perspective, here is the author's profile:
http://inspirehep.net/author/profile/C.Xiong.2

 

[BiGyElLoWhAt]

Nothing really stood out to me, other than Citation count, affilliations, and the lack of collaboration. His fields of study seemed to be all semi-related. Is there something that I should be looking at specifically here?

 

[David Horgan]

This paper is legitimate in the context of the Pati–Salam model see for example:http://puhep1.princeton.edu/~mcdonald/examples/EP/pati_prd_10_275_74.pdf

http://arxiv.org/pdf/hep-ph/0310006

andhttp://www.physics.ohio-state.edu/~raby/raby.world.summit.2006.preprint.pdf

 

[BiGyElLoWhAt]

Man, so much stuff to go through. Thanks for the links, hopefully I can make it through them. Normally anything in this realm leads me down a trail of breadcrumbs in order to understand one paper. It'd be so cool to know stuff and not have to look it up everytime haha.

 

[BiGyElLoWhAt]

I don't understand this on the princeton link:
"3)If appropriate spontaneous-symmetry breaking is postulated, there is the (logically independant) possibility of baryonic quarks transforming into leptons, with a violation of baryon and lepton number conservation"

They say previously that all models of gauge interactions share these qualities. Isn't the standard model a gauge theory? If not then I suppose my question is irrelevant. This seems like a contradiction, since, I believe, SM predicts these 2 conservations.

 

[BiGyElLoWhAt]

So upon some google searching, yes it is a gauge theory. So I guess my question really is what is the "appropriate spontaneous symmetry breaking" to violate this conservation? In undergrad terms would be great!

 

[arivero]

I don't understand this on the princeton link:
"3)If appropriate spontaneous-symmetry breaking is postulated, there is the (logically independant) possibility of baryonic quarks transforming into leptons, with a violation of baryon and lepton number conservation".

In ttyplical 4th colour models, two things happen when going down from SU(4) to SU(3): the diagonal traceless matrix (-1, +1/3, +1/3, + 1/3) is assigned to represent a quantum number that is the difference between Barion and Lepton number of a particle. We call it B-L. And we are still left with 14 "4th-gluons" that we need to reduce to 8... the other 6 are the ones changing from quark to lepton and back, so violating the previous quantum number.

 

[BiGyElLoWhAt]

That kind of reminds me of a commutator, at least in the way that you explained it. Does that stem from the same principles, by any chance?

 

[arivero]

Well, it is a U(1) generator that is expected to conmute with the broken group. Usually they break SU(4) down to SU(3) x U(1) but the U(1) is not electromagnetism (can not be, as EM comes from the electroweak force) but is is still a U(1), and works as a "B-L" label to separate quarks from leptons. I believe to remember that there was different positions about if it should be considered a gauge group generator or simply a global symmetry, and there was some attempts to mix it with the U(1) from the electroweak part.

 

[ohwilleke]

http://arxiv.org/abs/1503.09158
Is this a legitimite thing? I've never heard of 4th color charge or quark-lepton unification.

It is an idea that has been around for a long time and is much less ambitious than supersymmetry or string theory, for example. There isn't any positive empirical evidence for it, but it is a way to play with numbers that seems to provide some unification. One of the motivations for it is to explain baryongenesis and the matter-antimatter asymmetry of the universe. But, there isn't really any consensus on when this BSM physics would start to manifest itself.

 

[BiGyElLoWhAt]

I just find it really attractive because everythin ultimitely ends up getting broken down into 2 types of parties in the preon theories theyre talking about. I find the fact that quarks are fundamental hard to believe.

 

[BiGyElLoWhAt]

What do you mean it usually gets broken down versus built up? If I understood what I read out of the article and links provided, they're building SU (4)

 

[BiGyElLoWhAt]

Ok, after a shower and some coffee, I think I see what you both are saying. So with regards to the assymetry,

One of the motivations for it is to explain baryongenesis and the matter-antimatter asymmetry of the universe. But, there isn't really any consensus on when this BSM physics would start to manifest itself.

https://en.wikipedia.org/wiki/Rishon_model
This seems to not so much explain it, but discount it, as electrons are made up of anti-Thirds.

With respect to the U(3)xU(1), are you referencing this:
$\left ( \begin{array}{c} F_1 \\ F_2 \\ F_3 \\ F_4 \\ \end{array} \right )$ $\otimes \left ( \begin{array}{cccc} B_1 & B_2 & B_3 & B_4 \\ \end{array} \right )$

Spoiler

Alright, I'm sorry, I know this is just a box of code, but I can't seem to find what's wrong with it. Hopefully this makes sense...


HOLY CRAP... that one \...

Also, slightly off topic, but not necessarily:
Is the difference between U(n) and SU(n) just the determinant? Or is there more to it?