arXiv subjects

Wen-Hao Bian

Publications and source records attributed to Wen-Hao Bian.

8 recordsLinked to original sources

arXiv2026

Tunable phase transitions from semimetals to Chern insulators in two-dimensional quadratic-band-crossing materials

We systematically investigate how static symmetry-breaking perturbations and dynamic Floquet terms via a polarized light manipulate the topological phase transitions in the two-dimensional quadratic-band-crossing-point (QBCP) materials. The Berry curvature shows distinct behavior in such two situations. It is linearly and quadratically proportional to the product of microstructural parameters $t_{x,z}$ for the former and the latter, respectively. The static perturbation eliminates the QBCP and opens an energy gap, which leads to the momentum-inversion symmetry of Berry curvature. This yields a nontrivial Chern number determined by the microstructural parameters. In contrast, we demonstrate that either a circularly or an elliptically polarized light breaks the time-reversal symmetry, transforming the QBCP semimetal into a Chern insulator with a quantized anomalous Hall conductivity $σ_{xy} = Ce^2/\hbar$, where the Chern number is governed by the polarization angle. Moreover, the linear polarization preserves the central antisymmetry of the Berry curvature, giving rise to a topological trivial insulator. These results establish a tunable topological phase transition from a QBCP semimetal to Chern insulator in the two-dimensional QBCP materials.

cond-mat.mes-hall↗

arXiv2026

Quasinormal modes of coupled metric-dilaton perturbations in two-dimensional stringy black holes

We investigate the quasinormal modes (QNMs) associated with intrinsic metric-dilaton coupled perturbations of the Mandal-Sengupta-Wadia (MSW) black hole in two-dimensional string theory. Through suitable field redefinitions, the gravity-dilaton system is expressed in terms of the conformal factor and a redefined dilaton field, allowing the linear perturbation equations to be reduced to coupled Schrodinger-type eigenvalue equations in the tortoise coordinate. By imposing the standard QNMs' boundary conditions of purely ingoing waves at the horizon and purely outgoing waves at spatial infinity, we numerically determine the complex frequency spectrum. All modes satisfy Im$(ω)<0$, confirming the linear stability of the MSW black hole under intrinsic coupled perturbations. Unlike external scalar-field perturbations, which yield purely imaginary frequencies, the intrinsic perturbations generically exhibit nonvanishing real parts, corresponding to oscillatory modes of the gravity-dilaton sector. The real part of the frequency displays a nonmonotonic dependence on the overtone number, while increasing the central-charge parameter $\sqrt{k}$ systematically decreases the damping rate and prolongs the relaxation time. These results indicate that intrinsic perturbations probe internal dynamical degrees of freedom and reveal characteristic features of the relaxation dynamics of two-dimensional stringy black holes.

gr-qc↗

arXiv2026

Massive scalar field perturbations in noncommutative-geometry-inspired Schwarzschild black hole

In this paper, based on noncommutative-geometry-inspired Schwarzschild black hole, we employ a third-order WKB approximation approach to systematically calculate the quasinormal mode frequencies (QNFs), greybody factors (GFs), and absorption cross section (ACS) under massive scalar field perturbations. The results show that the QNFs satisfy Im($ω$)<0, confirming the stability of the black hole under perturbations. Furthermore, increasing the noncommutative parameter $θ$ reduces the absolute values of both the real and imaginary parts of the frequency, while increasing mass $μ$ increases the real part and reduces the imaginary part. The GFs and ACS increase with increasing $θ$ and decrease with increasing $μ$, indicating opposite modulation effects of these two types of parameters. It is worth emphasizing that the QNFs of the extreme black hole approach the corresponding values of the classical Schwarzschild black hole at angular quantum number $\ell=1$ and large $μ$, suggesting that, the effects of mass and noncommutative geometry quantum corrections cancel each other out to some extent. It is hoped that these results provide a viable theoretical basis for both the theoretical and experimental aspects of the perturbative dynamics of black hole.

gr-qc↗

arXiv2025

Kaon and Pion Fragmentation Functions

The Drell-Levy-Yan relation is employed to obtain pion and kaon elementary fragmentation functions (EFFs) from the hadron-scale parton distribution functions (DFs) of these mesons. Two different DF sets are used: that calculated using a symmetry-preserving treatment of a vector $\times$ vector contact interaction (SCI) and the other expressing results obtained using continuum Schwinger function methods (CSMs). Thus determined, the EFFs serve as driving terms in a coupled set of hadron cascade equations, whose solution yields the complete array of hadron-scale fragmentation functions (FFs) for pion and kaon production in high energy reactions. After evolution to scales typical of experiments, the SCI and CSM FF predictions are seen to be in semiquantitative agreement. Importantly, they conform with a range of physical expectations for FF behaviour on the endpoint domains $z\simeq 0, 1$, e.g., nonsinglet FFs vanish at $z=0$ and singlet FFs diverge faster than $1/z$. Predictions for hadron multiplicities in jets are also delivered. They reveal SU$(3)$ symmetry breaking in the charged-kaon/neutral-kaon multiplicity ratio, whose size diminishes with increasing reaction energy, and show that, with increasing energy, the pion/kaon ratio in $e^+ e^- \to h X$ diminishes to a value that is independent of hadron masses.

hep-ph↗

arXiv2025

Critical fates induced by the interaction competition in three-dimensional tilted Dirac semimetals

The interplay among Coulomb interaction, electron-phonon coupling, and phonon-phonon coupling has a significant impact on the low-energy behavior of three-dimensional type-I tilted Dirac semimetals. To investigate this phenomenon, we construct an effective theory, calculate one-loop corrections arising from all these interactions, and establish the coupled energy-dependent flows of all associated interaction parameters by adopting the renormalization-group approach. Deciphering such coupled evolutions allows us to determine a series of low-energy critical properties for these materials. At first, we present the low-energy tendencies of all interaction parameters. The tilting parameter exhibits distinct tendencies that depend heavily upon the initial anisotropy of fermion velocities. In comparison, the latter is mainly dominated by its initial value but is less sensitive to the former. Variations in these two quantities drive certain interaction parameters toward the strong anisotropy in the low-energy regime, indicating the screened interaction in specific directions, and others toward an approximate isotropy. Additionally, we observe that the tendencies of interaction parameters can be qualitatively clustered into three distinct types of fixed points, accompanied by the potential instabilities that induce an interaction-driven phase transition to a certain superconducting state. Furthermore, approaching these fixed points leads to the critical behavior of physical quantities, such as the density of states, compressibility, and specific heat, which exhibit quite different from their noninteracting counterparts and even deviate slightly from Fermi-liquid behavior. Our investigation sheds light on the intricate relationship between different types of interactions in these semimetals and provides useful insights into their fundamental properties.

cond-mat.str-el↗

arXiv2025

Low-energy critical behavior in two-dimensional tilted semi-Dirac semimetals driven by fermion-fermion interactions

Employing the renormalization group approach, we carefully investigate the critical behavior of two-dimensional tilted semi-Dirac semimetals induced by the fermion-fermion interactions in the low-energy regime. After incorporating all one-loop corrections, we derive the coupled RG equations of all related parameters and introduce two distinct strategies, named as Strategy I and Strategy II, to describe different scenarios. A detailed numerical analysis yields several interesting behavior in the low-energy limit. At first, we notice that the fermion-fermion interactions either vanish or diverge in the Strategy I, depending on the initial values of the tilting parameter and the fermionic couplings, whereas these interactions in the Strategy II always diverge at a certain critical energy scale, which is associated with the initial conditions. Next, the microstructural parameter $α$ and the fermion velocity $v_F$ in the Strategy I share the similar behavior with their Strategy II counterparts. It is observed that fermion-fermion interactions lead to an increase in $α$ while driving a decrease in $v_F$. Furthermore, the system can either be attracted by the Gaussian fixed point (GFP) or certain relatively fixed point (RFP) in the Strategy I. However, it always flow towards the RFP in the Strategy II at the lowest-energy limit. These results would provide helpful insights into the studies on observable quantities and phase transitions in the two-dimensional tilted semi-Dirac semimetals and the analogous semimetals.

cond-mat.str-el↗

arXiv2024

Critical behavior around the fixed points driven by fermion-fermion interactions and disorders in the nodal-line superconductors

We systematically investigate the intricate interplay between short-range fermion-fermion interactions and disorder scatterings beneath the superconducting dome of noncentrosymmetric nodal-line superconductors. Employing the renormalization group that unbiasedly treats all kinds of potential degrees of freedom, we establish energy-dependent coupled flows for all associated interaction parameters. Decoding the low-energy information from these coupled evolutions leads to the emergence of several intriguing behavior in the low-energy regime. At first, we identify eight distinct types of fixed points, which are determined by the competition of all interaction parameters and dictate the low-energy properties. Next, we carefully examine and unveil distinct fates of physical implications as approaching such fixed points. The density of states of quasiparticles displays a linear dependence on frequency around the first fixed point, while other fixed points present diverse frequency-dependent behavior. Compressibility and specific heat exhibit unique trends around different fixed points, with the emergence of non-Fermi-liquid behavior nearby the fifth fixed point. Furthermore, after evaluating the susceptibilities of the potential states, we find that a certain phase transition below the critical temperature can be induced when the system approaches the fifth fixed point, transitioning from the nodal-line superconducting state to another superconducting state. This research would enhance our understanding of the unique behavior in the low-energy regime of nodal-line superconductors.

cond-mat.supr-con↗

arXiv2023

Effects of the interplay between fermionic interactions and disorders in the nodal-line superconductors

We study the interplay between fermion-fermion interactions and disorder scatterings beneath the superconducting dome of noncentrosymmetric nodal-line superconductors. With the application of renormalization group, several interesting low-energy behaviors are extracted from the coupled equations of all interaction parameters. At the clean limit, fermion-fermion interactions decrease with lowering the energy scales but conversely fermion velocities climb up and approach certain saturated values. This yields a slight decrease or increase of the anisotropy of fermion velocities depending upon their initial ratio. After bringing out four kinds of disorders designated by the random charge ($Δ_{1}$), random mass ($Δ_{2}$), random axial chemical potential ($Δ_{3}$), and spin-orbit scatterers ($Δ_{4}$) based on their own unique features, we begin with presenting the distinct low-energy fates of these disorders. For the presence of sole disorder, its strength becomes either relevant ($Δ_{1,4}$) or irrelevant($Δ_{2,3}$) in the low-energy regime. However, the competition for multiple sorts of disorders is capable of qualitatively reshaping the low-energy properties of disorders $Δ_{2,3,4}$. Besides, it can generate an initially absent disorder as long as two of $Δ_{1,2,3}$ are present. In addition, the fermion-fermion couplings are insensitive to the presence of $Δ_4$ but rather substantially modified by $Δ_1$, $Δ_2$, or $Δ_3$, and evolve towards zero or certain finite non-zero values under the coexistence of distinct disorders. Furthermore, the fermion velocities flow towards certain finite saturated value for the only presence of $Δ_{2,3}$ and vanish for all other situations. As to their ratio, it acquires a little increase once the disorder is subordinate to fermionic interactions, otherwise keeps some fixed constant.

cond-mat.supr-con↗