- #1
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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AI Thread Summary
There is no systematic method to count all possible Feynman diagrams with vertices less than or equal to n in quantum field theory (QFT). To determine the number of distinct diagrams, one must compute all possible unconnected Green functions using the generating functional approximation. The discussion also clarifies that two specific Feynman diagrams related to Compton scattering are indeed distinct contributions. This highlights the complexity of diagram counting in QFT. Overall, the conversation emphasizes the challenges in quantifying Feynman diagrams systematically.
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- #3
dextercioby
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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.
Neglect gravity other than that of water; neglect friction.
F1=ρgsh=1000*10*1*(1+4)=50000 N;
F1=ρgsh=1000*10*0.1*4=4000 N;
F3=50000-4000=46000 N?
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook.
Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water.
I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system
$$M(t) = M_{C} + m(t)$$
$$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$
$$P_i = Mv + u \, dm$$
$$P_f = (M + dm)(v + dv)$$
$$\Delta P = M \, dv + (v - u) \, dm$$
$$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$
$$F = u \frac{dm}{dt} = \rho A u^2$$
from conservation of momentum , the cannon recoils with the same force which it applies.
$$\quad \frac{dm}{dt}...
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