# CERN quark experiments

1. Feb 17, 2015

### StephvsEinst

Hi! Does anyone know the most fundamental experiments that CERN did involving the discover of anything related to quarks? What is the most recent and important discover of CERN about quarks (heavy quarks)?

Thank you.

2. Feb 17, 2015

### Staff: Mentor

Nearly all CERN high-energy physics experiments after ~1970 relied on the concept of quarks and the results cannot be understood without.
The heavy quarks were all discovered at other sites, but CERN contributed to their study.

It is hard to rank discoveries by their importance and the relationship to quarks.

3. Feb 17, 2015

### StephvsEinst

Ok, I guess my question was wrongly formulated. Do you know/have you read some interesting papers about experiments with quarks written by someone from CERN?

4. Feb 17, 2015

### Staff: Mentor

I think the question is still too broad. All LHC experiments analyze proton-proton collisions, which involve quarks. The same applies to the old SPS experiments. It is like asking for astronomy observations using telescopes: sure there are some that did not use telescopes, but those are the exception.
LHCb is a whole experiment dedicated to studies of hadrons with heavy quarks. ALICE is specialized on quark/gluon plasmas.

All ATLAS papers (minus a few papers with "M. Atlas" as author)
All CMS papers
All LHCb papers
ALICE papers

5. Feb 18, 2015

### vanhees71

If there's one single experiment in history of science related to quarks, the first thing coming to my mind is the socalled "November revolution", where the charm quark was discovered, or more precisely put, charmonium has been found, the particle which we call $J/\psi$ since then. However, it was not discovered at CERN but in parallel at the same time in 1974 at the Stanford Linear Accelerator Center (SLAC) and at the Brookhaven National Laboratory (BNL). It was one of the triumphes of theory, having predicted the existence of a fourth quark flavor in order to explain the suppression of flavor-chaning neutral currents (Bjorken, Glashow 1964 and Glashow, Iliopoulus, Maiani 1970; nowadays known as the GIM mechanism and one of the cornerstones of the electroweak sector of the Standard Model, Quantum Flavor Dynamics).

Somwhat later, a 3rd generation of quarks has been predicted in order to explain CP violation (Kobayashi, Maskawa 1973). The bottom quark was discovered in 1977 at Fermilab, and the top quark, the hitherto last guy in the club, also at Fermilab in 1995.

CERN is most famous for the discovery of the gauge bosons of the weak interaction, the W- and Z0 bosons in 1983 and, of course, more recently the discovery of the Higgs boson (2012).

6. Feb 18, 2015

### ChrisVer

About quarks? I think the last I read was the confirmation of the $Z(4430)$ candidate tetraquark state ($c\bar{c} d \bar{u}$) with $\sim 14 \sigma$. However the particle was observed in Belle around 7 years prior to CERN's discovery/confirmation.
Also I haven't been updated whether it's really an exotic tetraquark state or any other kind of resonance/bound state.

7. Feb 18, 2015