Genus two partition functions of chiral conformal field theories

A systematic analysis of the genus two vacuum amplitudes of chiral self-dual conformal field theories is performed. It is explained that the existence of a modular invariant genus two partition function implies infinitely many relations among the structure constants of the theory. All of these relations are shown to be a consequence of the associativity of the operator product expansion, as well as the modular covariance properties of the torus one-point functions. U sing these techniques we prove that for the proposed extremal conformal field theories at c = 24k a consistent genus two vacuum amplitude exists for all k, but that this does not actually check the consistency of these theories beyond what is already testable at genus one

A new 'normal'

In a recent piece, Jon Bebb (2023) has argued that we have no reason to believe, contrary to what is often assumed, that ‘normal’ is ambiguous between a statistical and a normative sense. I argue that his case rests on two false premisses, and that we have very good reasons to believe that ‘normal’ is, in fact, ambiguous in this way. As part of my argument, I will go on to suggest that if ‘normal’ is ambiguous between a statistical and a normative sense, that is because of the deep but seldom recognised connection between regularities and rules. This suggestion, if correct, will in turn help us elucidate three familiar thoughts about normality

Resonant Raman scattering on single crystals of (BEDT-TTF)2Cu(NCS)2

Resonant Raman spectra of the organic superconductor (BEDT-TTF)2Cu(NCS)2 have been measured at 1.3 K as well as at 120 K. The Raman data do not show a superconducting gap opening in the investigated two dimensional superconducting system. The vibrational modes found in the Raman spectra are discussed and assigned. Possible mechanisms for resonance conditions in such two-dimensional organic superconducting systems are proposed

Raman investigations on single crystals and polycristalline pressed samples of organic superconducters

The investigation of molecular vibrations is a powerful tool which can increase our knowledge on structures and on electron molecular vibrations, which are due to charge oscillation between dimerized moIecuIes,coupled with totally symmetric intramolecular modes. Raman scattering studies account for totally symmetric vibrations. In addition, Raman spectroscopy can take advantage of resonant effects. In fact, when resonant conditions are fulfilled, selected molecular vibrations are obtained as well as information on the electronic manifold involved in the resonance process. In this paper, we report on Raman investigations of polycrystalline pressed materials of superconducting tempered -α(BEDT-TTF)2I3, called in the following, αt-{BEDT-TTF)2I3 and on untempered α(BEDT-TTF)2I3. Furthermore we report on the polarized resonant Raman scattering in the superconducting regime of (BEDT-TTF)2Cu(NCS)2 single crystals