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


Feb
17
comment Can dimensional regularization solve the fine-tuning problem?
For example: take the toy $\phi^4$ model you describe above - I would say this model is not fine tuned. However, this is only a toy model. A real particle of interest is the Higgs and this is only a $\phi^4$ model in the low energy limit. It is extremely likely there is new physics that talks to the Higgs that will result in a fine tuning of its mass. At the very least there is gravity and would expect new particles of the planck mass.
Feb
17
comment Can dimensional regularization solve the fine-tuning problem?
@innisfree I get what you are saying that $\Lambda$ does not have to correspond to a massive particle and I agree. I would go even further and say the following: Say you have a model with a light scalar field. And say there are no new massive particles that are being ignored and no new physics of scale M that creates perturbative OR non-perturbative corrections to your light scalar. Then I would say your model is absolutely not fine tuned.
Feb
15
comment Wald General Relativity, Chap 7.1
I think you might need to flesh this out for those of us without Wald sitting in front of us...
Feb
15
comment Can dimensional regularization solve the fine-tuning problem?
@JeffDror - what I mean is that even dim reg won't hide tuning against a physical scale like that of a massive particle, and that is the fine tuning that matters. That is, start with a model that has some heavy particles coupled to some light scalar fields and integrate out the heavy fermions - then you will see the fine tuning in any regularization procedure, dim reg or otherwise.
Feb
15
comment Can dimensional regularization solve the fine-tuning problem?
@innisfree : It is like JeffDror said above - $\Lambda$, the cutoff, is the energy scale at which our model fails and new physics comes in. The energy scale at which our model fails is that one at which there are new particles of mass $\Lambda$ that we were otherwise ignoring.
Feb
14
comment Can dimensional regularization solve the fine-tuning problem?
I really disagree with this answer but I am not going downvote because I find it a bit antagonistic in this situation. I posted my answer below, please feel free to comment and we can discuss.
Feb
14
answered Can dimensional regularization solve the fine-tuning problem?
Jan
1
comment Polarization vectors of massive and massless particles
Related:physics.stackexchange.com/questions/31143/…
Dec
31
comment Electromagnetic duality
Potentially worth a read: maths.ed.ac.uk/~jmf/Teaching/Lectures/EDC.pdf Definitely worth a read:users.ictp.it/~pub_off/lectures/lns007/Strassler/Strassler.pdf
Dec
18
comment How do you define a reversible path for general processes?
hwlau - I am not sure what you mean by "...(sub)system, not path..." - Since $\delta Q$ is a path dependent quantity, don't I have to, in practice, specify what path I am taking in order to use the equation $dS = \frac{\delta Q}{T}$?
Dec
18
comment How do you define a reversible path for general processes?
+1 - thanks for taking the time to answer.
Dec
17
asked How do you define a reversible path for general processes?
Oct
27
comment Finding out the potential
I think you should think about what the meaning of the 'distance' in the denominator is.
Aug
22
awarded  Nice Question
Aug
2
comment Large and small gauge transformations?
pg 23 of this reference talks a little bit about this lepp.cornell.edu/~pt267/files/documents/A_instanton.pdf
Jul
10
comment Is the Higgs field really disconnected from gravity?
Related: physics.stackexchange.com/questions/54415/higgs-boson-graviton
Jul
6
comment What exactly are we doing when we set $c=1$?
@dimension10 - Thanks for the correction regarding $ d \tau $ verse $ds$. As far as the metric signature goes, I am an unapologetic particle physicist.
Jul
6
revised What exactly are we doing when we set $c=1$?
deleted 5 characters in body
Jul
3
comment Cutoff regularization: Why not cutoff exactly at the momentum reached in an experiment?
I am not quite sure where you are confused. Let me just add this - this is a quantum mechanical system so we need to add all possible 'paths' between the in and out state. One of the things we need to sum over is the loop momentum, which ends up just being the momentum integral. In other words, no experimentalist can say what the loop momentum will be. This is the same way no experimentalist can say which slit the electron goes through in the double slit experiment. Does this clarify?
Jul
3
comment Cutoff regularization: Why not cutoff exactly at the momentum reached in an experiment?
The fact that we are integrating over all loop momentum to begin with means that these momenta are not constrained to a maximum value by momentum conservation.