Alexander Wowchik | Searcharxiv

arXiv2026

Renormalised thermodynamics for Bose gases from low to critical temperatures

We compute thermodynamic properties of dilute Bose gases using non-perturbative approximations of the two-particle irreducible (2PI) effective action. It is shown how to systematically renormalise the self-consistent descriptions beyond conventional Gaussian approximations such as Hartree-Fock-Bogoliubov theory. This allows us to determine the condensate depletion from low to high temperatures, including its critical behaviour at the phase transition. While the universal anomalous dimension at criticality is vanishing for Gaussian approximations, we determine its non-zero value at next-to-leading order of a self-consistent expansion in the number of field components.

cond-mat.quant-gas↗

arXiv2025

Generic Chiral Anomaly and Planar Hall Effect in a Non-Weyl System

The condensed-matter version of the chiral anomaly describes how electrons are pumped from a Weyl node with negative chirality to a Weyl node with positive chirality using parallel electric and magnetic fields. Key experimental signatures are a negative longitudinal magnetoresistance (LMR) and the planar Hall effect (PHE), both of which have been experimentally observed. Here, we show that the chiral anomaly explains key features of magnetotransport in the nodal-line semimetal ZrTe$_5$ despite the absence of Weyl points. The anomaly physics applies generically to materials in the quantum limit, when electron transport becomes quasi-one-dimensional, provided that Fermi velocities remain sufficiently large. This explains not only the negative LMR but also the PHE with a gigantic Hall angle and a highly unusual magnetic-field-angle dependence in ZrTe$_5$.

cond-mat.mes-hall↗