Angle-Resolved Loss of Landau Quasiparticles in 2D Hubbard Model

The problem of weakly correlated electrons on a square lattice is studied theoretically. A simple renormalization group scheme for the angle-resolved weight Z of the quasiparticles at the Fermi surface is presented and applied to the Hubbard model. Upon reduction of the cutoff the Fermi surface is progressively destroyed from the van Hove points toward the zone diagonals. Due to the renormalized Z, divergences of both antiferromagnetic and superconducting correlation functions are suppressed at the critical scale, where the interactions diverge.Comment: 13 pages, 2 figures, submitted to Europhysics Letter

Angle-resolved study of density-waves, superconductivity and pseudogap in two dimensions

Weakly correlated electrons on a square lattice are studied by angle-resolved functional renormalization group. Upon renormalization the interaction starts to depend on momenta and has pole-like solutions near a doping-dependent characteristic critical energy scale. Near half-filling this scale is the pseudogap temperature T*. In the overdoped regime the critical scale is the mean-field like critical temperature for d-wave superconductivity.Comment: 4 pages, 2 figure

New SDW phases in quasi-one-dimensional systems dimerized in the transverse direction

The spin density wave instabilities in the quasi-one-dimensional metal (TMTSF)_2ClO_4 are studied in the framework a matrix random phase approximation for intra-band and inter-band order parameters. Depending on the anion ordering potential V which measures the lattice doubling in the transverse direction, two different instabilities are possible. The SDW_0 state at low values of V is antiferromagnetic in b direction and has the critical temperature that decreases rapidly with V. The degenerated states SDW_(+-), stable at higher values of V, are superpositions of two magnetic orders, each one on its subfamily of chains. As V increases the ratio between two components of SDW_(+-) tends to zero and the critical temperature increases asymptotically towards that of SDW instability for a system having perfect nesting and no anion order. At intermediate V the metallic state can persist down to T=0.Comment: Submitted to Europhysics Letter

Colloidal stability of tannins: astringency, wine tasting and beyond

Tannin-tannin and tannin-protein interactions in water-ethanol solvent mixtures are studied in the context of red wine tasting. While tannin self-aggregation is relevant for visual aspect of wine tasting (limpidity and related colloidal phenomena), tannin affinities for salivary proline-rich proteins is fundamental for a wide spectrum of organoleptic properties related to astringency. Tannin-tannin interactions are analyzed in water-ethanol wine-like solvents and the precipitation map is constructed for a typical grape tannin. The interaction between tannins and human salivary proline-rich proteins (PRP) are investigated in the framework of the shell model for micellization, known for describing tannin-induced aggregation of beta-casein. Tannin-assisted micellization and compaction of proteins observed by SAXS are described quantitatively and discussed in the case of astringency

Magnetic oscillations and field induced spin density waves in (TMTSF)_2ClO_4

We report an analysis of the effects of magnetic field on a quasi-one-dimensional band of interacting electrons with a transverse dimerizing potential. One-particle problem in bond-antibond representation is solved exactly. The resulting propagator is used to calculate the spin-density-wave (SDW) response of the interacting system within the matrix RPA for the SDW susceptibility. We predict the magnetic field induced transition of the first order between interband SDW_0 and intraband SDW_(+-) phases. We reproduce the rapid oscillations with a period of 260 Tesla and the overal profile of the TMTSF_2ClO_4 phase diagram.Comment: 6 pages, 3 figure

Pauli and orbital effects of magnetic field on charge density waves

Taking into account both Pauli and orbital effects of external magnetic field we compute the mean field phase diagram for charge density waves in quasi-one-dimensional electronic systems. The magnetic field can cause transitions to CDW states with two types of the shifts of wave vector from its zero-field value. It can also stabilize the field-induced charge density wave. Furthermore, the critical temperature shows peaks at a new kind of magic angles.Comment: 3 pages, 1 figure include

Competing SDW Phases and Quantum Oscillations in (TMTSF)2ClO4 in Magnetic Field

We propose a new approach for studying spin density waves (SDW) in the Bechgaard salt (TMTSF)2ClO4 where lattice is dimerized in transverse direction due to anion ordering. The SDW response is calculated in the matrix formulation that rigorously treats the hybridization of inter-band and intra-band SDW correlations. Since the dimerization gap is large, of the order of transverse bandwidth, we also develop an exact treatment of magnetic breakdown in the external magnetic field. The obtained results agree with the experimental data on the fast magneto-resistance oscillations. Experimentally found 260T rapid oscillations and the characteristic Tc dependance on magnetic field of relaxed material are fitted with our results for anion potential of the order of interchain hopping

The Moving Image and the Time of Prophecy: Trauma and Precognition in L. Von Trier’s Melancholia (2011) and D. Villeneuve’s Arrival (2016)

Both the deferred recurrence of post-traumatic symptoms and the foresight granted by prophetic vision bring about a disruption of temporality and generate a chronological discontinuity which is often formally rendered as narrative discontinuity. This similarity produces an interpretive ambiguity that is central to the films, Melancholia (2011) by Von Trier and Arrival (2016) by Denis Villeneuve. Both movies begin by hinting at the post-traumatic origin of visions and then gradually shift towards a prophetic explanation. In addressing these two case studies, this article approaches prophecy and its temporality from a narratological perspective, integrating the critical parameters of trauma-theory with the contribution of Agamben’s concept of “Messianic time” and of Mahayana Buddhism

U-J Synergy Effect for the High Tc Superconductors

Using renormalization group and exact diagonalization of small clusters we investigate the ground state phase diagram of a two-dimensional extended Hubbard model with nearest-neighbor exchange interaction J, in addition to the local Coulomb repulsion U. The main instabilities are antiferromagnetism close to half-filling and d-wave superconductivity in the doped system. Our results suggest that the combined action of J and U interactions provide a remarkably efficient mechanism to enhance both d-wave superconducting and antiferromagnetic correlations.Comment: Final version, to appear in PR