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vincentchan
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Is there a systematical way to count all the possible feynman diagram with vertices less than or equal to n...
Counting Feynman Diagrams with n Vertices
- Thread starter vincentchan
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In summary, Feynman diagrams are graphical representations used to describe particle interactions in quantum field theory. They are important in physics for their ability to visually depict complex calculations and make predictions. The number of diagrams with n vertices can be calculated using a formula, and the process of counting involves considering all possible arrangements of lines. These diagrams can also be used to calculate physical quantities, but they have limitations in their use for high energies and do not account for all interactions.
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They're not.There are the 2 (distinct) contributions to the Compton scattering of electrons (if i saw well,or positrons in the other case).
To the first question:nope,in general u cannot tell how many distinct Feynman diagrams a QFT has in a certain order.U have to compute all possible unconnected Green functions,using the approximation for the generating functional.
Daniel.
To the first question:nope,in general u cannot tell how many distinct Feynman diagrams a QFT has in a certain order.U have to compute all possible unconnected Green functions,using the approximation for the generating functional.
Daniel.
1. What are Feynman diagrams and why are they important in physics?
Feynman diagrams are graphical representations of mathematical expressions that are used to describe interactions between particles in quantum field theory. They are important in physics because they provide a visual tool for understanding complex calculations and making predictions about the behavior of particles in subatomic interactions.
2. How many Feynman diagrams are there with n vertices?
The number of Feynman diagrams with n vertices is given by the formula (2n)!/[(n+1)!n!], where n is the number of vertices. For example, there are 24 Feynman diagrams with 3 vertices and 1260 diagrams with 5 vertices.
3. How do you count Feynman diagrams with n vertices?
The process of counting Feynman diagrams with n vertices involves identifying all possible ways in which the vertices can be connected by lines representing particle interactions. This can be done systematically by considering different arrangements of lines and applying the rules of the specific theory being studied.
4. Can Feynman diagrams with n vertices be used to calculate physical quantities?
Yes, Feynman diagrams with n vertices can be used to calculate physical quantities such as cross sections and decay rates. This is because the diagrams represent the mathematical expressions that describe particle interactions, and these can be used to calculate observable quantities.
5. Are there any limitations to using Feynman diagrams with n vertices?
While Feynman diagrams are a powerful tool for understanding and calculating particle interactions, there are some limitations to their use. They are most commonly used in perturbative calculations, which means they are not suitable for describing interactions at very high energies or in extreme conditions such as black holes. Additionally, they only represent a simplified version of reality and do not take into account all possible interactions between particles.
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