Experimental verification of QFT?

In summary, important experimental verifications of QFT that someone studying QFT should be familiar with include the anomalous magnetic moment of the electron, the Lamb shift, the Higgs mechanism, the Casimir effect, and spontaneous emission of atoms in excited states. These experiments provide evidence for the existence of short-range forces with massive quanta and are consistent with the predictions of the Standard Model of Particle Physics with a single, real scalar field (a.k.a. "Higgs boson"). Famous experiments that have contributed to these verifications include LEP-I at CERN, experiments at Fermilab and SLAC, and smaller experiments at BNL, JLab, DESY, KEK, etc. The Particle Data Group's website is
  • #1
pellman
684
5
What are the important experimental verifications of QFT that someone studying QFT should be familiar with?

The wikipedia QED article mentions the anomalous magnetic moment of the electron and the Lamb shift.

The Higgs Mechanism article states "Although the evidence for the Higgs mechanism is overwhelming, accelerators have yet to produce a Higgs boson". The evidence is overwhelming? Ok, what is that evidence? From what I can tell by the description in the article, it just seems that, given our understanding of how QFT's work, the existence of short range forces with massive quanta requires there to be a Higgs mechanism within the theory. So the "evidence" might simply be that it is logically necessary within the theory, e.g., there exist massive force carriers --> there must be a Higgs mechanism.

Anyway, the Higgs question is somewhat secondary. If you know of experiments that strongly support it, please include them here.


Even better, if you can give the name of scientists who performed the experiment, that would be great. And if you know of any textbooks which summarize such experiments, that would be supercalifragilisticexpialidocious.
 
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  • #2
Two more come to mind, spontaneous emission of atoms in excited states is a prediction of QED not of ordinary QM, and the Casmir effect has been experimentally verified several times.
 
  • #3
AstroRoyale said:
Two more come to mind, spontaneous emission of atoms in excited states is a prediction of QED not of ordinary QM, and the Casmir effect has been experimentally verified several times.

Casimir effect, yes. Good one. Emission though I would say is the sort of thing which any QED candidate would have to incorporate. It is the very thing which the theory was developed to explain, so of course it has to do that much.
 
  • #4
pellman said:
The Higgs Mechanism article states "Although the evidence for the Higgs mechanism is overwhelming, accelerators have yet to produce a Higgs boson". The evidence is overwhelming? Ok, what is that evidence? From what I can tell by the description in the article, it just seems that, given our understanding of how QFT's work, the existence of short range forces with massive quanta requires there to be a Higgs mechanism within the theory. So the "evidence" might simply be that it is logically necessary within the theory, e.g., there exist massive force carriers --> there must be a Higgs mechanism.

Anyway, the Higgs question is somewhat secondary. If you know of experiments that strongly support it, please include them here.

The reason we say that the usual Standard Model of Particle Physics with a single, real scalar field (a.k.a. "Higgs boson") is very well-supported by the evidence comes from precision measurements. People have calculated (to at least one loop, sometimes two) the contributions such a particle would make to various physical quantities such as the left-right asymmetries of electroweak gauge boson decays, g-2 of the electron/muon, etc. This list is quite extensive. The measurements that have been made to date agree remarkably well with the predictions that follow from a Higgs boson being there with a mass right around 114 GeV. Of course, this evidence must be taken with a grain of salt, and it typically is in the particle physics community, since just because it's "consistent" doesn't mean it must be that way. But that is what people mean.

Even better, if you can give the name of scientists who performed the experiment, that would be great. And if you know of any textbooks which summarize such experiments, that would be supercalifragilisticexpialidocious.

There are many (very large) experiments that have carried out these measurements. The most famous is the LEP-I experiment at CERN in the 1980's and early 90's. The many experiments at Fermilab and SLAC have also contributed significantly, as well as smaller experiments at BNL, JLab, DESY, KEK, etc. For a great summary of all of this, you can look up "Electroweak Precision" on the Particle Data Group's website (www-pdg.lbl.gov)
 
  • #5
Well, I was just saying that spontaneous emission is a feature of QFT (QED) that is experimentally known to happen of course, and is a feature exclusive to QFT and not ordinary QM.
 
  • #6
AstroRoyale said:
Well, I was just saying that spontaneous emission is a feature of QFT (QED) that is experimentally known to happen of course, and is a feature exclusive to QFT and not ordinary QM.

I know. And thanks for replying.
 
  • #7
Thanks, Blechman.
 
  • #8
pellman said:
Casimir effect, yes. Good one. Emission though I would say is the sort of thing which any QED candidate would have to incorporate. It is the very thing which the theory was developed to explain, so of course it has to do that much.

As a historical note, the first drive towards QED was made by Bethe as an explanation of the Lamb shift.
 

1. What is QFT?

QFT stands for Quantum Field Theory, which is a theoretical framework used to describe the behavior of subatomic particles and their interactions. It combines principles from quantum mechanics and special relativity to provide a complete understanding of the microscopic world.

2. Why is experimental verification of QFT important?

Experimental verification of QFT is important because it allows us to test the predictions and assumptions made by the theory. This helps to validate the theory and ensure that it accurately describes the behavior of particles in the real world. It also allows us to discover new phenomena and expand our understanding of the universe.

3. How is QFT experimentally verified?

There are several ways in which QFT can be experimentally verified. One method is through particle accelerators, where high-energy particles are collided and their interactions are observed. Another method is through precision measurements of particle properties, such as mass and charge, which can be compared to the predictions of QFT. Additionally, experiments involving quantum entanglement and quantum teleportation can also provide evidence for QFT.

4. What are some examples of experiments that have verified QFT?

Some examples of experiments that have verified QFT include the Large Hadron Collider (LHC) at CERN, which confirmed the existence of the Higgs boson, a fundamental particle predicted by QFT. Other experiments, such as the Double-Slit Experiment and the Stern-Gerlach Experiment, have also provided evidence for the principles of QFT.

5. Are there any current challenges in experimentally verifying QFT?

While QFT has been successfully verified in many experiments, there are still some challenges that researchers are working to overcome. One challenge is the reconciliation of QFT with general relativity, which describes gravity on a large scale. Another challenge is the search for new particles and interactions that are not yet accounted for in QFT. Additionally, the precise measurement of certain particle properties, such as the mass of the neutrino, is still an area of active research.

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