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Article
Open AccessS-matrix positivity without Lorentz invariance: a case study
We investigate the analytic structure of scattering amplitudes in theories in which Lorentz invariance is spontaneously broken. We do so by computing and studying the S-matrix for a simple example: a superflui...
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Article
Open AccessApparently superluminal superfluids
We consider the superfluid phase of a specific renormalizable relativistic quantum field theory. We prove that, within the regime of validity of perturbation theory and of the superfluid effective theory, ther...
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Article
Open AccessA technical analog of the cosmological constant problem and a solution thereof
The near vanishing of the cosmological constant is one of the most puzzling open problems in theoretical physics. We consider a system, the so-called framid, that features a technically similar problem. Its st...