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 Feb 29 awarded Popular Question Nov 7 awarded Nice Question Oct 8 awarded Popular Question Mar 19 awarded Yearling Sep 24 awarded Autobiographer Jul 2 awarded Curious Mar 19 awarded Yearling Dec 29 awarded Taxonomist Mar 19 awarded Yearling Jul 29 awarded Popular Question Mar 19 awarded Yearling Mar 4 comment Instantons and Borel Resummation @SidiousLord: good point. But I'm more interested in seeing an application in a specific problem, which Weinberg's book hasn't done. Mar 4 asked Instantons and Borel Resummation Jan 15 comment How to prove equivalence of RG flow of QFT coupling constant and diagrammatic resummation at fixed renormalization scale? I think the diagrams not only need to look like a series of loops, one encircling each others, but also need to be strongly ordered in loop momenta, with inner loops having much less momenta so appear as effective vertices to outer loops. In other words, we are looking at a reduced part of the phase space. The question is then how to prove it's this part of the phase space that gives leading behaviour. Another question is how to show that a generic N-loop diagram is "sub-leading" compared with diagrams that are reducible to N successive 1-loop diagrams. Jan 14 asked How to prove equivalence of RG flow of QFT coupling constant and diagrammatic resummation at fixed renormalization scale? Jan 6 asked Is the axial gauge with a $\xi$ term useful in Yang-Mills theory? Dec 25 accepted Do people confuse all-order perturbation theory with non-perturbative physics in QFT? Dec 17 comment Dimensional Regularization Integral Formula I have an example where $\Delta$ is negative. Consider the one-loop EM vertex correction for fermion-fermion scattering in QED. Ignoring fermion masses, we have $\Delta=-x(1-x)q^2$, where $q^2$ is the photon virtuality. Now $q^2$ is -ve for t-channel elastic scattering, but +ve for s-channel scattering, so $\Delta$ may have either signs. Dec 17 asked Dimensional Regularization Integral Formula Dec 16 accepted Which collision energy at LHC is better for hunting 125 GeV Higgs, 7 TeV, 8 TeV or 14 TeV?