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I'm a physics grad student just trying to figure out all this stuff like everyone else.


Mar
7
comment Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
I disagree that you take $\epsilon\rightarrow 0$ only after you have defined your counter terms. At least if we restrict ourselves to $\bar{MS}$- this prescription you are asking about is defined as subtracting off $\frac{1}{\epsilon}$ plus some finite stuff. You are only going to get a $\frac{1}{\epsilon}$ after expanding in small $\epsilon$. That is, you should expand everything that has a $\epsilon$ in it, and collect powers of $\epsilon$. I am thinking about how to answer this any better.
Mar
7
comment Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
I am not sure what you mean by `dimensionful logarithm' - are you referring to the argument of the logarithm, or the dimensions of the prefactor?
Mar
7
comment Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
OK, I can come back to that if you want. I edited again, let me know if this clarifies things at all.
Mar
7
revised Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
added 612 characters in body
Mar
7
comment Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
If I understand you correctly, there just isn't anything to protect you from getting $\mu^2$ terms in your 2 point function for a scalar. A scalar mass is susceptible to quadratic corrections to any mass scale you have that enters your loops. So, dimensionally we expect them.
Mar
7
comment Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
@alexarvanitakis - I edited as per your $\mu^{2 \epsilon}$ comment, let me know if I still didn't answer it. As for the $\phi^3$ model, I am a little unclear what you are asking - are you asking why you get a factor of $\mu^2$ left over in the 1 loop correction to the 2 point function in this case? Please elaborate.
Mar
7
revised Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
addressing comment
Mar
7
answered Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
Mar
7
revised Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
Fixed the mass term of the Lagrangian
Mar
7
suggested suggested edit on Can't find the mass scale; calculation using the modified minimal subtraction scheme and dimensional regularisation
Mar
5
answered Calculating force of impact
Mar
5
comment Can black holes be created on a miniature scale?
@RonMaimon - thanks for taking the time for the thorough comments- much appreciated!
Mar
5
comment A man running on the treadmill
I think you should clarify by what you mean by 'the man doesn't fall' when the treadmill stops. I think you mean he doesn't stop running? Whether the man stops running or falls or changes speed critically depends on what the man does, not just whether the treadmill stops.
Mar
5
comment Can black holes be created on a miniature scale?
@RonMaimon - does the Goldberger-Wise mechanism not adress stabilizing the extra dimension in a natural way?
Mar
4
comment If you had two “perfectly” flat surfaces of the same material?
I don't know about diamond, but for some materials friction might be a moot point. See en.wikipedia.org/wiki/Cold_welding
Mar
4
comment Gradient of the electric potential
+1 - Thanks for fleshing this out.
Mar
3
comment Evaluate Commutator with Partial Derivatives
Have you worked with partial derivatives before? I would say just keep expanding out the expression you have.
Mar
3
comment Gradient of the electric potential
You can ask all the questions you want. The electric field doesn't depend on your choice for zero potential since the electric field is the gradient of the potential. Only differences in potential energy are meaningful, and electric potential is just electric potential per unit charge, so only differences in electric potential are meaningful.
Mar
3
comment Gradient of the electric potential
The electric field will always point in the direction of maximum decrease. This direction will depend on the sign of the charge, so they will be opposite for oppositely charged objects. But it still points in the direction of maximum decrease.
Mar
3
revised Differences between orthogonality and Kronecker delta function?
Cleaned it up a bit