Speaker
Description
In this work (arXiv:2405.09450), we study the low-energy effective field theory of the full Fermi surface at the Ising-nematic quantum critical point using the recently developed field-theoretic functional renormalization group (RG). Given that the theory is strongly coupled in two spatial dimensions, we employ dimensional regularization to systematically access the theory in a controlled manner, beginning at d = 5/2. Our analysis reveals that the Fermi momentum, when measured in units of the low-energy scale, continuously grows under RG. Consequently, the space of IR fixed points can only be described projectively. We illustrate the non-trivial implications of this projective nature through two key examples. First, it leads to a discrepancy between the scaling dimension and the relevance of coupling functions. Second, there is no single dynamical critical exponent that universally governs the scaling between energy and momentum across all low-energy observables. Moreover, we identify another critical dimension, dsc, below which superconducting instabilities emerge in the true low-energy limit. Above this dimension, the projective fixed point remains stable and we establish that two marginal coupling functions—the Fermi surface shape function and the Fermi velocity—determine all the coupling functions that define the space of projective fixed points.
| Keywords | Non-Fermi liquid theory, Renormalization group, Quantum criticality |
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| Submitter's Email Address | [email protected] |
| Recording Permission | YES |
| Virtual Audience Permission | YES |
| Photography Permission | YES |
