#1 Non-Hermitian free-fermion critical system and Logarithmic conformal field theory
Iao-Fai Io
Logarithmic conformal field theory (LCFT) describes critical phenomena in non-Hermitian systems. In this work, we study a (1+1)D non-Hermitian massless free-fermion field theory and confirm its conformal invariance. We construct an infinite set of operators that satisfy the Virasoro algebra and identify the central charge c = −2. The spectrum of this model exhibits an indecomposable Jordan-cell structure, indicating that it is an LCFT. We compute the indecomposability parameters β and find that they coincide with those of the symplectic fermion theory, suggesting a close connection between the two theories.
#2 Anomalous Chiral Anomaly in Spin-1 Fermionic Systems
Shantonu Mukherjee
Chiral anomaly is a key feature of Lorentz-invariant quantum field theories: in presence of parallel external electric and magnetic fields, the number of massless Weyl fermions of a given chirality is not conserved. In condensed matter, emergent chiral fermions in Weyl semimetals exhibit the same anomaly, directly tied to the topological charge of the Weyl node, ensuring a quantized anomaly coefficient. However, many condensed matter systems break Lorentz symmetry while retaining topological nodes, raising the question of how chiral anomaly manifests in such settings. In this work, we investigate this question in spin-1 fermionic systems and show that the conventional anomaly equation is modified by an additional nontopological contribution, leading to a nonquantized anomaly coefficient. This surprising result arises because spin-1 fermions can be decomposed into 2-flavor Weyl fermions coupled to a Lorentz-breaking, momentum-dependent non-Abelian background potential. The interplay between this potential and external electromagnetic fields generates the extra term in the anomaly equation. Our framework naturally generalizes to other Lorentz-breaking systems beyond the spin-1 case.
#3 Entanglement in gapless topological phases in a p-wave superconductor
Jayendra Nath Bandyopadhyay
We investigate gapless topological phases of a p-wave superconductor using entanglement-based diagnostics. Despite the absence of a full bulk gap, the entanglement spectrum exhibits bulk–boundary correspondence. For contractible bipartitions, the entanglement entropy shows nonmonotonic behavior with peaks at bulk gap closings, indicating topological phase transitions that persist in the thermodynamic limit. For noncontractible bipartitions, the entanglement entropy follows a volume law in the gapless phase. These results highlight the interplay between symmetry, entanglement, and topology and demonstrate the effectiveness of entanglement measures in identifying unconventional gapless topological phases.
#4 Information-theoretic principle of emergent 1-form symmetries
Wen-Tao Xu
#5 Lattice Translation Modulated Symmetries and TFTs
Ching-Yu Yao
Modulated symmetries are internal symmetries that are dependent to their position. Recent studies show that some of the symmetry-protected topological (SPT) phases fail to survive in the presence of the modulation. I generalize the discussion to the lattice translation modulated symmetries beyond invertible symmetries in 1+1D via the tensor network language. Although the topological behaviors are broken because of the presence of modulations, I construct the modulated version of the symmetry TFT bulks, and recover some known results in invertible cases.
#6 Boundary critical phenomena in the quantum Ashkin-Teller model
Yifan Liu
We investigate the boundary critical phenomena of the one-dimensional quantum Ashkin-Teller model using boundary conformal field theory and density matrix renormalization group (DMRG) simulations. Based on the \mathbb{Z}_2-orbifold of the c=1 compactified boson boundary conformal field theory, we construct microscopic lattice boundary terms that renormalize to the stable conformal boundary conditions, utilizing simple current extensions and the underlying \mathrm{SU}(2) symmetry to explicitly characterize the four-state Potts point. We validate these theoretical identifications via finite-size spectroscopy of the lattice energy spectra, confirming their consistency with D_4 symmetry and Kramers-Wannier duality. Finally, we discuss the boundary renormalization group flows among these identified fixed points to propose a global phase diagram for the boundary criticality.
#7 Non-orientable surfaces for non-Hermitian systems
Haruki Shimizu
The Klein bottle ratio provides universal values other than the central charge. Here, we extend the Klein bottle ratio and the $\mathrm{RP}^2$ ratio to non-Hermitian systems with periodic boundary conditions. Using the Yang-Lee model, we confirm the behavior of these ratios, as well as the generalized entanglement entropy. We also observe universal behaviors of these ratios for the non-Hermitian critical 5-state Potts model.
#8 Leading all-loop quantum contribution to the effective potential in general scalar field theory
Vladislav Filippov
We calculate the leading divergences of the effective potential for an arbitrary scalar theory on a curved spacetime background. Based on the recurrence relation between the leading poles following from the locality condition, we obtain a system of generalised renormalisation group equations that can be studied numerically or analytically in some special cases. We study the simplest effective potentials for power-like models and give a comparison of them in the framework of cosmological phenomenology.
#9 Emergent geometry from the entanglement of fractional charges of zigzag graphene nanoribbon
Hoang-Anh Le
The topological order in zigzag graphene nanoribbons arises from the interplay between edge termination, electron–electron interactions, and disorder. The topological order manifests in several ways, including a universal value of the topological entanglement entropy and the presence of e-/2 fractional charges localized at the zigzag edges. In this work, we investigate the long-range entanglement between these fractional charges. We embed the ribbon into an AdS-like bulk geometry and employ the mutual information to quantify the entanglement. We demonstrate the geometric emergence in the entanglement where the edge-to-edge mutual information plays a role as geodesic distance in hyperbolic space. Our results offer a holographic picture of fractionalized degrees of freedom in quasi-one-dimensional systems.