Particles That Flock: Aczel's Scientific American Article

[gendou2]

"Particles that Flock"

Aczel had an interesting article in Scientific American this month:

http://www.scientificamerican.com/article.cfm?id=particles-that-flock

The article doesn't go into much detail, but I found it odd that the phenomena only occurs when a large number of particles (> 110) are produced in a collision.

I wonder how they ruled out Jets from hadronization? Maybe the energies are too low.
http://en.wikipedia.org/wiki/Jet_(particle_physics)

Has anyone seen any technical articles on the subject?

 

[Vanadium 50]

See http://www.springerlink.com/content/18j075w18321q5h6/".

 

[the_house]

Wow, science journalism is frustrating. The least they could do is link to the paper (see Vanadium's link, or equivalently http://arxiv.org/abs/arXiv:1009.4122). If I wasn't already familiar with it, I would have no idea what they were talking about.

The article doesn't go into much detail, but I found it odd that the phenomena only occurs when a large number of particles (> 110) are produced in a collision.

Yes, and note that these are fairly rare events. Normally there are an order of magnitude fewer particles produced. It also only shows up in a particular range of transverse momentum, which is also interesting.

I wonder how they ruled out Jets from hadronization? Maybe the energies are too low.
http://en.wikipedia.org/wiki/Jet_(particle_physics)

The reason it's so interesting is that it can't be generated from jets. It's not clear in the article, but the correlation in question is between pairs of particles emitted at the same azimuthal angle, but at very different angles with respect to the beam. Jets produce short-range correlations between particles that all go in a similar direction (as well as correlations from back-to-back jets for particles coming out in opposite azimuthal directions.) That's what I would call "flocking", rather than the "ridge" correlation that they seem to be talking about in this article, which is quite different.

 

[gendou2]

Thanks Vanadium, the_house!

 

[gendou2]

Seems like Fermilab has found the something similar:

http://arxiv.org/abs/1104.0699

 

[Vanadium 50]

No, that's totally different.