arXiv subjects

Yi-Li Wang

Publications and source records attributed to Yi-Li Wang.

11 recordsLinked to original sources

arXiv2026

Linear Resistivity from Spatially Random Interactions and the Uniqueness of Yukawa Coupling

Recent studies have shown that a spatially random Yukawa-type interaction between a Fermi surface and critical bosons can produce linear-in-temperature resistivity, the defining signature of strange metals. In this article, we systematically classify all scalar couplings of the form $(ψ^{\dagger}ψ)^nϕ^m$ in arbitrary dimensions to identify possible candidates for strange-metal behaviour within this disordered framework. We find that only spatially random Yukawa-type interaction in $(2+1)$ dimensions can yield linear resistivity. This indicates that linear resistivity is not a universal property of all spatially random scalar coupling, and strange-metal property replies on both dimensions and interaction type.

hep-th↗

arXiv2026

Towards Bulk Locality: A Systematic Construction of Contact Interactions from Chord Diagrams

Chord diagrams encode boundary correlators in the double-scaled holographic Sachdev-Ye-Kitaev model, but currently capture only a limited class of bulk interactions that yield pure power-law correlators. In this article, we investigate a general construction based on Fock-space flux models with arbitrary periodic lattice size, clarifies how lattice dimensions control probe configurations and bulk contact vertices. Developing a systematic matching scheme and using the chord path integral formalism, we compute three- to six-point contact correlators and reproduce a broad class of AdS$_2$ scalar contact Witten diagrams, including those with logarithmic singularities. The results demonstrate that chord diagrams, in full generality, provide a microscopic description of bulk contact interactions and thereby establish a principled framework for reconstructing bulk locality from boundary data.

hep-th↗

arXiv2025

ER=EPR and Strange Metals from Quantum Entanglement: Disorder theory vs quantum gravity

We give an understanding how strange metals arise from the spatially random Yukawa-SYK model based on the wormhole picture and find a parallelism between the disorder theory and quantum gravity. We start from the observation that the Gaussian average over the spatial random coupling gives a wormhole, defined as a mechanism for long range interaction without causal suppression outside the lightcone. We find that the large-$N$ limit equivalence of the quenched and annealed averages provides a field theory version of the ER=EPR. Since the wormhole establishes momentum exchanges over arbitrary distance without causal suppression, it provides a mechanism of the planckian dissipation. It also tells us why SYK-like models describe strongly interacting systems even in the small coupling case. We classify the disorder samples into two classes: I) spatially random coupling with wormholes and no information loss, II) spatially uniform coupling with decoherence.

hep-th↗

arXiv2025

Hall Angle of a Spatially Random Vector Model

Strange metals exhibit linear resistivity and anomalous Hall transport, yet a comprehensive theory that accounts for both phenomena is still lacking. Recent studies have shown SYK-like spatially random couplings between a Fermi surface and a bosonic field, either scalar or vector type, can yield linear-$T$ resistivity. In this paper, we continue the investigation on a vector coupling in the presence of a magnetic field. We compute the fermion and boson propagators, along with the self-energy and polarization functions, and determine their dependence on the magnetic field. Although the Hall angle does not exhibit the signature of strange-metal, the linear-in-temperature resistivity remains at low temperatures. Results indicate that random interactions can robustly support linear transport, though additional ingredients may be required to capture the full phenomenology of strange metals.

hep-th↗

arXiv2025

Linear-T Resistivity from Spatially Random Vector Coupling

Recently, Patel et al. introduced a higher dimensional version of the SYK model with random coupling in a Yukawa interaction to find the linear-$T$ resistivity. We test the universality of the mechanism by replacing the scalar field with a vector field in various dimensions. We find that it works for vector and scalar interactions, although the details are largely different. However, this mechanism for the linear-$T$ resistivity works only in $(2+1)$ dimensions and not in higher dimensions, regardless of the interaction type. Based on these results, we explore the rôle of spatial random disorder and find a simple explanation of how such random scattering converts the Fermi liquid to a strange metal by changing the self-energies of the involved bosons and fermions.

hep-th↗

arXiv2024

Effective anisotropic dynamics in Group Field Theory cosmology

We study the emergent dynamics of an anisotropic universe in the context of Group Field Theory condensate cosmology, with a scalar field playing the role of a relational clock. According to different definitions of ``isotropy'', two anisotropic condensate states are considered and the Bianchi-like dynamics of cosmological anisotropic observables, as well as their quantum fluctuations, are analysed. We find that both anisotropic states become isotropic at late time, reproducing an effective Friedmann dynamics, while anisotropies give small but non-negligible contributions at earlier times, closer to the cosmic bounce.

gr-qc↗

arXiv2023

Spherically-symmetric geometries in a matter reference frame as quantum gravity condensates

Candidate microstates of a spherically symmetric geometry are constructed in the group field theory formalism for quantum gravity, for models including both quantum geometric and scalar matter degrees of freedom. The latter are used as a material reference frame to define the spacetime localization of the various elements of quantum geometry. By computing quantum geometric observables, we then match the quantum states with a spherically symmetric classical geometry, written in a suitable matter reference frame.

gr-qc↗

arXiv2023

Generalised Amit-Roginsky model from perturbations of 3d quantum gravity

A generalised Amit-Roginsky vector model in flat space is obtained as the effective dynamics of pertubations around a classical solution of the Boulatov group field theory for 3d euclidean quantum gravity, extended to include additional matter degrees of freedom. By further restricting the type of perturbations, the original Amit-Roginsky model can be obtained. This result suggests a general link (and possibly a unified framework) between two types of tensorial quantum field theories: quantum geometric group field theories and tensorial models for random geometry, on one hand, and melonic-dominated vector and tensorial models in flat space, such as the Amit-Roginsky model (and the SYK model), on the other hand.

hep-th↗

arXiv2021

Black holes in 4D Einstein-Maxwell-Gauss-Bonnet gravity coupled with scalar fields

Einstein-Maxwell-Gauss-Bonnet-axion theory in $4$-dimensional spacetime is investigated in this paper through a "Kaluza-Klein-like" process. Dual to systems at finite temperature with background magnetic field on three dimensions, the four-dimensional dyonic black hole solution coupled with higher derivative terms is obtained. After the tensor-type perturbation is added, the shear viscosity to entropy density ratio is calculated at high temperature and low temperature separately. The behaviour of shear viscosity to entropy density ratio of uncharged black holes is found to be similar with that in $5$-dimensional spacetime, violating the Kovtun-Starinets-Son bound as well when temperature becomes lower. In addition, the main feature of this ratio remains almost unchanged in $4$ dimensions, which is characterised by $(T/Δ)^2$ at low temperature $T$, with $Δ$ proportional to the coefficient $β$ from scalar fields. The difficulty in causal analysis is also discussed, which is mainly caused by the vanishing momentum term in equations of motion.

hep-th↗

arXiv2020

Violation of the viscosity/entropy bound in translationally invariant non-Fermi liquids

The shear viscosity is an important characterization of how a many-body system behaves like a fluid. We study the shear viscosity in a strongly interacting solvable model, consisting of coupled Sachdev-Ye-Kitaev (SYK) islands. As temperature is lowered, the model exhibits a crossover from an incoherent metal with local criticality to a marginal fermi liquid. We find that while the ratio of shear viscosity to entropy density in the marginal Fermi liquid regime satisfies a Kovtun-Son-Starinets (KSS) like bound, it can strongly violate the KSS bound in a robust temperature range of the incoherent metal regime, implying a nearly perfect fluidity of the coupled local critical SYK model. Furthermore, this model also provides the first translationally invariant example violating the KSS bound with known gauge-gravity correspondence.

hep-th↗

arXiv2016

Shear Viscosity to Entropy Density Ratio in Higher Derivative Gravity with Momentum Dissipation

We investigate $η/s$ in linear scalar fields modified Gauss-Bonnet theory that breaks translation invariance. We first calculate $η/s$ both analytically and numerically and show its relationship with temperature in log-log plot. Our results show that $η/s\sim T^2$ at low temperatures. The causality is also considered in this work. We then find that causality violation still happens in the presence of the linear scalar field and we suggest there is a Gauss-Bonnet coupling dependent lower limit for the effective mass of the graviton. If the effective mass of the graviton is big enough, then there will be no causality violation and hence no constraints for the Gauss-Bonnet coupling.

hep-th↗