Detecting Gluons: When & How?

In summary, Gluons were first detected in 1979 in PETRA (DESY, Hamburg, Germany) in 3-jet events resulting from e+e- collisions. This was later confirmed by deep inelastic e p collisions at HERA (DESY) and is supported by the validation of the quark-gluon (DGLAP) evolution equations in multiple high-energy phenomena. However, at lower energies, the models become more controversial due to the non-perturbative behavior of QCD.
  • #1
ghery
34
0
Hi to everyone:

Does anybody of you know when was the gluon detected?, and how do you detect gluons?

I hope you can answer
Thank you
 
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  • #2
You detect gluons with a stick-o-meter of course :tongue:

Seriously, I think it is considered that the first "direct" experimental observation of gluons is the 3-jet events discovered in e+e- collisions at PETRA (DESY, Hamburg, Germany) in 1979. There's a not too bad Wiki entry on it http://en.wikipedia.org/wiki/Three_jet_event

Personally, I find this kind of explanation a bit handwaving of course, but it is the kind of stuff that people tell experimentalist-students when they enter the field. A better explanation is of course that a Monte Carlo simulation based upon QCD containing gluons was statistically in agreement with the data taken there.

After this, there have been several other experimental confirmations of gluons, the most accurate being, I think, deep inelastic e p collisions (again, at DESY but with HERA this time). There are tons of publications by the two collaborations there (H1 and ZEUS).
 
  • #3
I completely agree with vanesh's answer. I only want to add to his last point that the DIS results can be gazed at here. The amount of data is stupendous. The fact that the points are not located on an horizontal line, called scaling violation, is in perfect agreement with QCD. To fully appreciate the extent of this data set, please take time to realize that we have logarithmic scales in two dimensions [itex](x_B,Q^2)[/itex].
 
  • #4
vanesch said:
Personally, I find this kind of explanation a bit handwaving of course, but it is the kind of stuff that people tell experimentalist-students when they enter the field. A better explanation is of course that a Monte Carlo simulation based upon QCD containing gluons was statistically in agreement with the data taken there.

I kind of like the hand-wavy stuff. I think about it this way - suppose QCD were incorrect. Then you wouldn't have this kind of numerical agreement you mention, but you would still need something very much like the gluon to explain the three-jet events. So the observation of these events tells you something about the kinds of theories that are supported by the data.
 
  • #5
vanesch is right. 3-jet events are the first and strongest evidence for the existence of gluons, but certainly aren't the only evidence. Validation of the quark-gluon (DGLAP) evolution equations in multiple high-energy phenomena (to at least 2nd order in perturbative QCD) is pretty solid evidence that the theory is correct, at least at high energy.

Go to lower energies (say, a virtual photon energy of less than 800 MeV), and the models get more controversial, due to the non-perturbative behavior of QCD at low energies. (Things get VERY difficult to calculate in that realm.)
 

1. What are gluons and why are they important in particle physics?

Gluons are subatomic particles that mediate the strong nuclear force, one of the four fundamental forces in nature. They are important in particle physics because they hold quarks together to form protons and neutrons, which are the building blocks of atomic nuclei.

2. How do scientists detect gluons?

Scientists detect gluons indirectly through the effects that they have on other particles. This is done by colliding particles at high energies and studying the resulting particle interactions and decay products.

3. What is the Large Hadron Collider (LHC) and how does it aid in detecting gluons?

The Large Hadron Collider (LHC) is the world's largest and most powerful particle accelerator. It accelerates particles to nearly the speed of light and smashes them together, allowing scientists to study the resulting particle interactions and detect the presence of gluons.

4. Can gluons be detected outside of particle accelerators?

No, gluons cannot be detected outside of particle accelerators. This is because they are constantly interacting with other particles and are only observable in the high-energy collisions produced by accelerators.

5. What are the potential implications of detecting gluons?

Detecting gluons can provide insight into the nature of the strong nuclear force and help us better understand the behavior of particles at the subatomic level. It can also aid in the development of new technologies and potentially lead to advancements in fields such as energy production and medicine.

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