Unparticles: scale invariant particle?

[Koen1]

I was pondering suggested exotic particle concepts recently,
got thinking about the "unparticle" suggested not long ago by
well known physicist Georgi.
For those who haven't heard the term before: the concept of the
"un-particle" appears to arise from certain quantumphysical model
characteristics that appear to allow scale invariant "particles".
In other words, a sort of "particle" is suggested to exist that
is fractal in nature, to a high degree.

Now I'm having a little trouble gettign a good handle on the exact
particle model of these "unparticles", but perhaps some others
in this forum have some more light to shed on the subject?
Of course, of particular interest is the possibility to use these
particles in some energy exchange format, to produce output
of energy in usable form.

Here's a few links:
- http://lanl.arxiv.org/abs/hep-ph/0703260
- http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVN-4RXJYM1-8&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c25cc07f306126427ae609dabf873bc4
- http://backreaction.blogspot.com/2007/09/unparticles.html
- http://www.physorg.com/news100753984.html
- http://nanoscale.blogspot.com/2007/11/unparticles-and-condensed-matter.html

[Feynman]

Thank you very much Koen!  I am going to print and review these papers

[rensseak]

I was pondering suggested exotic particle concepts recently,
got thinking about the "unparticle" suggested not long ago by
well known physicist Georgi.
For those who haven't heard the term before: the concept of the
"un-particle" appears to arise from certain quantumphysical model
characteristics that appear to allow scale invariant "particles".
In other words, a sort of "particle" is suggested to exist that
is fractal in nature, to a high degree.

Now I'm having a little trouble gettign a good handle on the exact
particle model of these "unparticles", but perhaps some others
in this forum have some more light to shed on the subject?
Of course, of particular interest is the possibility to use these
particles in some energy exchange format, to produce output
of energy in usable form.

Here's a few links:
- http://lanl.arxiv.org/abs/hep-ph/0703260
- http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TVN-4RXJYM1-8&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c25cc07f306126427ae609dabf873bc4
- http://backreaction.blogspot.com/2007/09/unparticles.html
- http://www.physorg.com/news100753984.html
- http://nanoscale.blogspot.com/2007/11/unparticles-and-condensed-matter.html

http://www.globalscaling.de/en/index.php

[Feynman]

Okay, I'll first say I have only had time to briefly review the first paper so far (Georgi, Unparticle Physics, Harvard). 

This is very interesting, and unfortunately the math is over my head.  However, I'll comment on the parts I do understand to try to make some sense of the implications.

http://lanl.arxiv.org/abs/hep-ph/0703260

Unparticle stuff with scale dimension dU looks like a
non-integral number dU of invisible particles.

Hmmm this reminds me of the Dirac Sea, the non-material "aether", the open/closed vibrating loops of strings etc.

The way the phase space factors compose in my normalization is...

Personally I am very suspicious of renormalization ,  so I'm not a fan of these sorts of transformations in general. I think it's a bit of a shell game.  (Renormalization are simply any math tricks which get rid of unwanted infinities in quantum electrodynamics and quantum chromodynamics.)  But hey, Los Alamos used it to split the atom so renormalization is a decent swiss army knife even if the ultimate picture of reality is incorrect...

The effective field theory picture above assumes that the unparticle fields do not carry
the standard model gauge interactions. It would be interesting to try to relax this, but
I have no idea whether it is possible.

This is very important implication of the unparticle theory. As my personal opinion of the standard model is I think it's crap, breaking the gauge interactions seems to be a precursor towards a new theory with better (read: more elegant) symmetry transformations.

In (2), (19), (20) and (24), we assumed that the unparticle operator is a bosonic field.
Fermionic fields are possible if the standard model fields include fermions and bosons
with the same gauge couplings, as in SUSY, or if one can makes sense of unparticle
fields with standard model gauge quantum numbers.

This is interesting.  As I understand, bosons are integer spin particles like photons.  Fermions of course are protons , neutrons etc.  What are the significance of using identical gauge couplings?  Are there identity between these (fermionic field and bosonic field)?   I do not know.

I had hoped briefly to make sense of unparticles with dU < 1. However, in the calcu-
lation leading to figure 1 the differential decay rate into unparticles with dU < 1 has a
non-integrable singularity as EU → 0, suggesting that the vacuum might be unstable. This is in accord with the general theorem in [11] that such fields are not possible in a
unitary theory (one of many important contributions by this author to the subject of
conformal field theory).

It's interesting how the author dispenses so quickly with the unstable vacuum!   I think this is a great area of investigation. Let's look at that reference for a moment, the 'general theorem' which says such fields are not possible just for arguments sake.

[11] G. Mack, ?All unitary ray representations of the conformal group su(2,2) with positive
     energy,? Commun. Math. Phys. 55 (1977) 1.

Hmm , okay so we are assuming SU(2,2) for symmetry and only positive energy.  In my personal opinion, I am wary of dispensing with negative energies as an unwanted mathematical byproduct.  Again, the universe is 70% "dark energy" according to cosmologists.  Could this perhaps relate to negative energy?   Also, I do not understand the math well enough here, but perhaps the author is actually looking at broken vacuum symmetry with unparticles dU < 1 .

[Koen1]

Unparticle stuff with scale dimension dU looks like a
non-integral number dU of invisible particles.

Hmmm this reminds me of the Dirac Sea, the non-material "aether", the open/closed vibrating loops of strings etc.

yeah, that's what I thought of as well

The way the phase space factors compose in my normalization is...

Personally I am very suspicious of renormalization ,  so I'm not a fan of these sorts of transformations in general. I think it's a bit of a shell game.  (Renormalization are simply any math tricks which get rid of unwanted infinities in quantum electrodynamics and quantum chromodynamics.)  But hey, Los Alamos used it to split the atom so renormalization is a decent swiss army knife even if the ultimate picture of reality is incorrect...

Again I share your view. Sort of.

The effective field theory picture above assumes that the unparticle fields do not carry
the standard model gauge interactions. It would be interesting to try to relax this, but
I have no idea whether it is possible.

This is very important implication of the unparticle theory. As my personal opinion of the standard model is I think it's crap, breaking the gauge interactions seems to be a precursor towards a new theory with better (read: more elegant) symmetry transformations.

hmm... more complete ones as well, I hope. Describing the often mentioned "asymmetry" in a more elaborate and complete symmetrical system, I would think...?

[This is interesting.  As I understand, bosons are integer spin particles like photons.  Fermions of course are protons , neutrons etc.  What are the significance of using identical gauge couplings?  Are there identity between these (fermionic field and bosonic field)?   I do not know.

Well just to give a quick jab at it here, was the theory not that the Higgs boson could explain the characteristic phenomenon of mass, of which a neutron for example has quite a lot but a proton for example has very little? So there appears to be some form of coupling there... Or maybe I just haven't had enough coffee yet.

Hmm , okay so we are assuming SU(2,2) for symmetry and only positive energy.  In my personal opinion, I am wary of dispensing with negative energies as an unwanted mathematical byproduct.  Again, the universe is 70% "dark energy" according to cosmologists.  Could this perhaps relate to negative energy?   Also, I do not understand the math well enough here, but perhaps the author is actually looking at broken vacuum symmetry with unparticles dU < 1 .

Heh, again I share your view, and I also am not well enough skilled in the math appllied there so with me, like you, it's -whoosh!- "wow did you see that?!"