One of the things that I gained a bit more understanding of during the course of this Nuclear conference that is going on now is the issue of the scattering and bound states, which I am going to say here in a very hand-waving way.
The point is the issue that the S-matrix of a QFT that you calculate on the lattice is very different from the one that in continuum. For sure. But then, how can we get information about the continuum S-matrix. The seminal work of Luscher showed how this can be done. He argued this information lies in how the energy levels scale. If it is a bound state then there is scaling by exp(-m*L) where m is the mass of the bound state and L the lattice size. On the other hand, if it is a scattering state then it will scale by 1/L^3. Thus, a S-matrix with only poles gives the information about the full spectrum of the continuum theory with both the bound and scattering states. There's some bit about the momentum dependence of the phase shifts that come in somewhere, but I dont know that yet. Will hopefully learn that while doing this project with Nilmani, Anyi and Shailesh.
Another nice movie: Udaan. Watched it yesterday. Somehow it resonated with me for obious reasons. If only I could get free like that right now. But alas, no! Only an ominous patience for me.
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