Detailed balance is a simple and powerful rule to describe the dynamics of two-state systems.

If you know the probability of a transition from a state A to the other state B of a physical system (in some appropriate time unit), and you also know the probability of the reverse reaction , then you automatically know what is equilibrium condition for N bodies distributed in the two states:

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Besides the usual share of random readers who google something and get directed here by mere chance (to be read: by the sheer amount of valuable information I have posted here), this blog is read by an interesting mix of particle physicists, students, experts in other fields of Physics, and Science amateurs -plus a small number of science reporters looking for news.

Of course I love each and every one of my faithful readers like good teachers love their pupils, but among the varied crowd, the readers which I am most happy to host here are students and amateurs, because they provide me with true motivation for spending my time writing popularization articles. Without them, many of my posts would lose their meaning.

One year ago, a paper by a distinguished group of theorists announced first evidence of new physics from measurements of the properties of B_s mesons performed at the Tevatron by the CDF and DZERO experiments. They had combined all the available information, obtaining a result which disagreed with the Standard Model (SM) prediction by more than three standard deviations.

A new paper on the ArXiV caught my attention this evening for several reasons. First of all, because two of its five authors (J.Ellis, J.R.Espinosa, G.F.Giudice, A.Hoecker, and A.Riotto) are (or have been) my colleagues in Padova University; second, because the title is quite catchy; third, because indeed the results it presents are valuable food for thought.