Could anyone help me to recognize the Atlas results?

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Discussion Overview

The discussion revolves around understanding how to draw Feynman diagrams based on experimental results from the Atlas detector at the LHC. Participants explore the complexities of particle interactions and the representation of these interactions through Feynman diagrams, particularly in the context of proton collisions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses interest in particle physics and seeks guidance on drawing Feynman diagrams for specific experimental results, mentioning the presence of electrons, muons, and hadrons.
  • Another participant suggests looking at Wikipedia for foundational information on Feynman diagrams.
  • A participant questions whether to represent the initial state of the collision as two protons or as W and Z bosons in the Feynman diagram.
  • It is noted that protons are not elementary particles, and the interaction involves partons (quarks and gluons) within the protons, complicating the representation of the interaction in a Feynman diagram.
  • One participant emphasizes that event displays are not practical for studying particle decays and that additional particles can be produced from the remnants of the protons after the hard interaction.

Areas of Agreement / Disagreement

Participants express differing views on how to approach drawing Feynman diagrams for proton collisions, with some emphasizing the complexity of the interactions and the role of partons, while others seek simpler representations. The discussion remains unresolved regarding the best method to depict these interactions.

Contextual Notes

The discussion highlights limitations in understanding the underlying mechanisms of particle interactions and the assumptions involved in representing complex collisions with Feynman diagrams. There is also a dependence on definitions of particles and interactions that may not be universally agreed upon.

kalok87
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Hallo, Dear particle physicist,

Despite I am major in biophysics, the particle physics looks attractive to me... So I just used Atlantis to check some experiments result from internet... Although I can find some resultant particles. I still cannot understand how to draw a Feynman diagram for them, because I have not learned the mechanism about it.

If it is possible, could you please give me some hints to do it? (In the attachment you can find those visualized data.)

For example, in the first picture (No.2 in the Data): I found there are electrons and muons and hadrons (do not know whether neutron or proton, they are in the same path as muons.), what is the Feynman diagram to describe this process?

Thx.
 

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Hi, Jedishrfu

If I want to start to draw a diagram in this case (for Atlas, LHC), what should I draw at left hand side? Should I draw P + P \rightarrow ( because it is the collision of 2 protons) or
W \rightarrow and Z \rightarrow ?
 
It is not possible to write the whole interaction with a Feynman graph.
Protons are not elementary particles (they consist of quarks and gluons). In a typical "interesting" collision, one particle ("parton") with significant energy from one proton collides with a parton from the other proton, releasing a lot of energy. The interesting particles (like W and Z bosons, top-quarks, Higgs and whatever) are produced in that interaction, and that can be written with a Feynman graph (example).
Apart from that hard interaction, you always have the rests of the protons hanging around - they can lead to many new gluons and quarks and those produce additional particles quickly afterwards.

Event displays like your images are not a practical method to study particle decays.
 

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