LHC Detects Evidence of New Physics

[n2doc]

By Lisa Grossman September 21, 2010 | 3:17 pm |



After nearly 6 months of smashing particles, the Large Hadron Collider has seen signs of something entirely new. Pairs of charged particles produced when two beams of protons collide seem to be associated with each other even after they fly apart.

“It is a small effect, but it is very interesting in itself,” said physicist Guido Tonelli, spokesperson for the LHC’s CMS experiment. Tonelli and colleagues announced the results in a seminar at CERN September 21 and in a paper submitted to the Journal of High Energy Physics.

The LHC finally got up and running in March after more than a year of false starts. Beams of protons were smashed together in the 17-mile-long ring at energies of 7 teraelectronvolts (TeV) — three times the energy that had been achieved before.


When two protons collide, they produce a flurry of smaller, short-lived charged particles that fly away from each other at certain angles and speeds. The CMS (Compact Muon Solenoid) experiment at the LHC detects the path each of these particles takes. Physicists can then use those tracks to reconstruct what happened at the heart of the collision, like reassembling shards of glass from a broken window.



Read More http://www.wired.com/wiredscience/2010/09/new-physics-at-lhc/

[Jim__]

1. I have a question on how to read the graphs.

Images: 1) Image of a 7 TeV proton-proton collision in CMS producing more than 100 charged particles. 2) The correlation functions for “minimum bias” collisions (left) and for collisions that produced at least 110 charged particles (right); the new ridge is indicated with an arrow. Credit: CERN/CMS Collaboration

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I assume that the correlation is shown along the vertical axis, the one with the label R(...). When I look at that graph, it looks like the measure of R in both graphs is negative (in the ridge area) and that it's a little bit less negative along the ridge in the graph on the right - I'm following the dotted lines on the vertical axis. Is the graph actually saying that the R function in the left graph is 0, and in the right graph, it's greater than 0 - IOW: Am I misreading the graph?

[Lochloosa]

2. I'm kicking just to see if someone can answer this f**&$(*#) question.

:evilgrin: :evilgrin:

[BadgerKid]

3. The "baselines" look different.

At left, in the ridge area R seems smooth and about -1 or slightly greater than -1. At right, the "baseline" around the ridge seems to drop to around -2.5 to -2, and the peak is about -1.3.

[Jim__]

4. Thanks for the reply.

It's really hard to locate 3-dimensional graphs. We appear to be looking down at this which could be causing a distortion. I wonder if we're missing a piece that uses color to position on the vertical dimension. The reason that I don't think we should be below 0 on the vertical is because this is a correlation function and from reading the article, I really expect this to be a positive correlation.

The -2 in the right-side graph is interesting. It implies that this correlation function is not a pure statistical correlation.