Galileo’s abjuration


Next year there will be a great chance in Rome to take a look to an important part of Vatican Secret Archives. These archives span almost two thousand years of history with the most part of them being part of the build up of Western civilization. Vatican made available a hundred documents that will be exposed from February to September 2012 at Musei Capitolini. You can see a correspondence between the Church of England and the Pope at the time of Henry the Eighth but what is more interesting for us as physicists is the Galileo’s signature in the abjure document. I give you here the picture of this fundamental aspect of the History and I hope it will convey you some of the feelings I experienced. Of course, being here in Rome, I will take the chance to visit this museum and see directly this exceptional witness.

Paper on critical temperature revised


Yesterday, I have uploaded a new version of my paper on the critical temperature of chiral symmetry breaking in QCD (see here). The reason for this was that there are some points in need for a better clarification. The main of these is the mapping theorem: I have added a sketch of a proof. The reason for this is that there is a common misunderstanding about it and that some people think  that this theorem is for quantum field theories. Indeed, it just establishes a map between classical solutions of a scalar field and a Yang-Mills field but in the asymptotic limit of a coupling going to infinity. Quantum theory does not enter at all here but these classical asymptotic solutions can be used to build up a perturbation theory for quantum field theory in the infrared, that is for low-energies, that is the range of interest for all the phenomenology we would like to understand.

Another recurring question is if this mapping breaks in some way gauge invariance. The answer is a resounding no as the proof does not select a gauge at the start but anyhow if one wants quantization a gauge must be selected.

Finally, I have better clarified the derivation of the critical temperature and added some more relevant references. I hope in this way that my arguments can be better understood. Indeed, presentation is one of the most difficult aspects of scientific communication and sometime it is a sound explanation of attrition between authors and referees.

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