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A very effective Hamiltonian in nuclear physics
Atomic nuclei are complex quantum many-body systems. Effective theories have helped provide a better understanding of them. The best-known a...
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Is it something to do with breakdown of the Born-Oppenheimer approximation? In molecular spectroscopy you occasionally hear this term thro... -
If you look on the arXiv and in Nature journals there is a continuing stream of people claiming to observe superconductivity in some new mat...
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I welcome discussion on this point. I don't think it is as sensitive or as important a topic as the author order on papers. With rega...
Just to verify that I understand (roughly) the origin of the "rigidity" of the order parameter… In the "mexican hat" picture, where the symmetry is broken by a free energy that goes as power 2n>2 in the (complex) order parameter, the order parameter for the ground state moves off the top of the hat and into the brim. Out on the brim, the powers 4 and over will begin to dominate the free energy, leading to a greater second derivative at the ground state, hence more "rigidity" in the modulus of the order parameter. Is this a good way to understand?
ReplyDeleteNo. This is not what the rigidity is about.
DeleteThe rigidity refers to spatial variations of the order parameter. The Mexican hat has many degenerate minima. At any one point in space the order parameter may have one of these values. I can have a slow spatial variation of the order parameter across the system. The rigidity refers to the total energy cost associated with these slow spatial variations.