Latest from the LHC

[bing434]

Interesting little article from the BBC about the latest success from the Large Hadron Collider at CERN:

BBC World Service - News - Cern Scientists celebrate Large Hadron Collider success

It also has a short extract from a telephone interview with our favourite popstar come physicist Dr Brian Cox

[CharmQuark]

The LHC has now reached their target for this year just a little bit of an update for you all

In 3 weeks time they are going to be starting the Heavy Ion collisions I wish them luck there is quite a few scared out there of Strangelets and false Vacuum. I also wish them luck in getting over their fear

For i was terrified of Micro Black Holes being made......I am now thankfully over this fear and loving learning about Black Holes

Charms

[toml42]

Recent results from the LHC suggest that Quarks are not the fundamental building blocks of all matter any more, and probably have their own components. Gentlemen, things are about to get messy...

[George Jones]

Recent results from the LHC suggest that Quarks are not the fundamental building blocks of all matter any more, and probably have their own components. Gentlemen, things are about to get messy...

I have heard the opposite.

The LHC is looking for quark substructure in at least two different ways.

1) The LHC looks for excited quark states. If a quark actually consists of several more elementary particles, then there should be excited quark states. As an analogy, consider a hydrogen atom, which consists of a proton and an electron. A hydrogen atom can exits in lowest (ground) state, or it can exist in excited, higher energy states.

2) The LHC tries to probe inside quarks. If stuff is shot at particles that contains quarks (for example, protons), then the stuff that is shot scatters in different ways depending on whether quarks are elementary or composite. As an analogy, consider the experiments performed by Rutherford that that demonstrated that nuclei are composite particles (i.e., they are made up of protons and neutrons).

Recently published papers claims that methods 1) and 2) at the LHC show no signs of quark substructure, and that the LHC has used methods 1) and 2) in a more sensitive fashion than experiments done elsewhere.

Method 1). From

[1008.2461] Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton Collisions with the ATLAS Detector at the LHC

These data exclude at the 95% CL excited-quark masses from the lower edge of the search region, 0.30 TeV, to 1.26 TeV for a standard set of model parameters and using the ATLAS default MC09 tune [27]. This result extends the reach of previous experiments and constitutes the first exclusion of physics beyond the Standard Model by the ATLAS experiment.

Method 2). From

[1009.5069] Search for Quark Contact Interactions in Dijet Angular Distributions in pp Collisions at sqrt(s) = 7 TeV Measured with the ATLAS Detector

Using 3.1 pb^−1 of data, quark contact interactions with a scale below 3.4 TeV are excluded at the 95% CL. The sensitivity of this analysis extends significantly beyond that of previously published studies.

[toml42]

ah, looks like i was a little out of date, i heard that there was evidence of excited quark states a few months ago, but this obviously supersedes that. Cheers for the links!