Chern-Simons Gauge Fields Research Articles

A kinetic description for the electromagnetic response of the charged particles to Chern–Simons gauge fields

In this paper, we introduce the Vlasov–Chern–Simons (VCS) equation, a Vlasov-type equation that describes the two-dimensional dynamics of charged particles affected by the Chern–Simons electromagnetic potentials. First, we derive the VCS equation from the Chern–Simons–Schrödinger equations, a quantum mechanical model for the particle affected by Chern–Simons gauge fields, via the Wigner transform. Subsequently, we study the local-in-time well-posedness for the strong solution and the global-in-time existence for weak solutions to the VCS equation, respectively. Additionally, we propose a simple numerical scheme of the semi-Lagrangian type for solving the VCS equation and provide numerical validation for the conservation of moments and Lp-norms.

Holographic dual of a quantum spin chain as a Chern-Simons-scalar theory

We construct a holographic dual theory of one-dimensional anisotropic Heisenberg spin chain, which includes two Chern-Simons gauge fields and a charged scalar field. Thermodynamic quantities of the spin chain at low temperatures, which are exactly calculated from the integrability, are completely reproduced by the dual theory on three-dimensional black hole backgrounds and the exact matching of the parameters between the dual theory and the spin chain is obtained. The holographic dual theory provides a new theoretical framework to analyze the quantum spin chain and one-dimensional quantum many-body systems. Published by the American Physical Society 2024

Fermions Coupled to Chern-Simons Gauge Field or Imaginary Chemical Potential and the Bloch Theorem

Fermions Coupled to Chern-Simons Gauge Field or Imaginary Chemical Potential and the Bloch Theorem

Emission distribution for the quantas of Maxwell–Chern–Simons gauge field coupled to external current

In this paper, we have investigated the nature of emission distribution of the Maxwell–Chern–Simons (MCS) theory in [Formula: see text] dimensions. The distribution of the topologically massive quanta seems to be Poissionian in nature just like the Maxwell field theory in [Formula: see text] dimensions but with a condition, without which the distribution takes an indeterminate form when we make the coupling term approach 0.

Two-Dimensional Electron-Hole System under the Influence of the Chern–Simons Gauge Field Created by the Quantum Point Vortices

In the present work the Chern-Simons(C-S) gauge field theory developed by Jackiw and Pi [1] and widely used to explain the fractional quantum Hall effects, was applied to describe the two-dimensional (2D) electron-hole (e-h) system in a strong perpendicular magnetic field under the influence of the quantum point vortices creating the Chern-Simons(C-S) gauge field. The composite particles formed by electrons and by holes with equal integer positive numbers of the attached quantum point vortices are described by the dressed field operators, which obey to the Fermi or to the Bose statistics depending on the even or odd numbers . It is shown that the phase operators as well as the vector and the scalar potentials of the C-S gauge field depend on the difference of the electron and of the hole density operators. They vanish in the mean field approximation, when the average values of the electron and of the whole densities coincide. Nevertheless, even in this case, the quantum fluctuations of the C-S gauge field lead to new physics of the 2D e-h system.

A two–dimensional electron–hole system under the influence of the Chern–Simons gauge field created by quantum point vortices

In the present work, the Chern–Simons (CS) gauge field theory developed by Jackiw and Pi [8] and widely used to interpret the fractional quantum Hall effects, is applied to describe a two-dimensional (2D) electron–hole (e–h) system in a strong perpendicular magnetic field and under the influence of quantum point vortices creating the CS gauge field. Composite particles formed by electrons and holes with equal integer positive numbers Ø of attached quantum point vortices are described by dressed field operators, which obey the Fermi or Bose statistics depending on even or odd numbers Ø . It is shown that the phase operators, as well as the vector and scalar potentials of the CS gauge field, depend on the difference between the electron and hole density operators. They vanish in the mean field approximation, when the average values of electron and hole densities coincide. Nevertheless, even in this case, the quantum fluctuations of the CS gauge field lead to new physics of the 2D e–h system.

Classification of solutions for self-dual Chern–Simons CP(1) model

In this paper, we consider the nonlinear equation arising from the Chern–Simons theory of planar matter fields interacting with the Chern–Simons gauge field in a CP(1) invariant fashion. Then, we establish the sharp region of flux for non-topological solutions and prove the classification of solutions of all types in the case of one vortex point. Moreover, we also give the complete result of Theorem 1.3 in the work by Choe et al. [J. Differ. Equations, 255, 2136 (2013)] from Theorem 1.4(ii) as follows.

Synthetic flux attachment

Topological field theories emerge at low energy in strongly-correlated condensed matter systems and appear in the context of planar gravity. In particular, the study of Chern-Simons terms gives rise to the concept of flux attachment when the gauge field is coupled to matter, yielding flux-charge composites. Here we investigate the generation of flux attachment in a Bose-Einstein condensate in the presence of non-linear synthetic gauge potentials. In doing so, we identify the U(1) Chern-Simons gauge field as a singular density-dependent gauge potential, which in turn can be expressed as a Berry connection. We envisage a proof-of-concept scheme where the artificial gauge field is perturbatively induced by an effective light-matter detuning created by interparticle interactions. At a mean field level, we recover the action of a "charged" superfluid minimally coupled to both a background and a Chern-Simons gauge field. Remarkably, a localised density perturbation in combination with a non-linear gauge potential gives rise to an effective composite boson model of fractional quantum Hall effect, displaying anyonic vortices.

Statistical physics of flux-carrying Brownian particles

Chern–Simons gauge field theory has provided a natural framework to gain deep insight about many novel phenomena in two-dimensional condensed matter. We investigate the nonequilibrium thermodynamics properties of a (two-dimensional) dissipative harmonic particle when the Abelian topological gauge action and the (linear) Brownian motion dynamics are treated on an equal footing. We find out that the particle exhibits remarkable magneticlike features in the quantum domain that are beyond the celebrated Landau diamagnetism: this could be viewed as the non-relativistic Brownian counterpart of the composite excitation of a charge and magneticlike flux. Interestingly, it is shown that the properties of such flux-carrying Brownian particle are in good agreement with the classical statistical mechanics at sufficient high temperatures, as well as are widely consistent with the Third Law of thermodynamics in the studied dissipative scenarios. Our findings also suggest that its ground state may be far from trivial, i.e. it is a seemingly degenerate state.

Holographic dual to charged SYK from 3D gravity and Chern-Simons

In this paper, we obtain a bulk dual to the low energy sector of the SYK model, including SYK model with U(1) charge, by Kaluza-Klein (KK) reduction from three dimensions. We show that KK reduction of the 3D Einstein action plus its boundary term gives the Jackiw-Teitelboim (JT) model in 2D with the appropriate 1D boundary term. The size of the KK radius gets identified with the value of the dilaton in the resulting near-AdS2 geometry. In presence of U(1) charge, the 3D model additionally includes a U(1) Chern-Simons (CS) action. In order to describe a boundary theory with non-zero chemical potential, we also introduce a coupling between CS gauge field and bulk gravity. The 3D CS action plus the new coupling term with appropriate boundary terms reduce in two dimensions to a BF-type action plus a source term and boundary terms. The KK reduced 2D theory represents the soft sector of the charged SYK model. The pseudo-Nambu-Goldstone modes of combined Diff/SL(2, ℝ) and U(1)local/U(1) transformations are represented by combined large diffeomorphisms and large gauge transformations. The effective action of the former is reproduced by the action cost of the latter in the bulk dual, after appropriate identification of parameters. We compute chaotic correlators from the bulk and reproduce the result that the contribution from the “boundary photons” corresponds to zero Liapunov exponent.

Flows, fixed points and duality in Chern-Simons-matter theories

It has been conjectured that 3d fermions minimally coupled to Chern-Simons gauge fields are dual to 3d critical scalars, also minimally coupled to Chern-Simons gauge fields. The large N arguments for this duality can formally be used to show that Chern-Simons-gauged critical (Gross-Neveu) fermions are also dual to gauged ‘regular ’ scalars at every order in a 1/N expansion, provided both theories are well-defined (when one fine-tunes the two relevant parameters of each of these theories to zero). In the strict large N limit these ‘quasi-bosonic’ theories appear as fixed lines parameterized by x6, the coefficient of a sextic term in the potential. While x6 is an exactly marginal deformation at leading order in large N, it develops a non-trivial β function at first subleading order in 1/N. We demonstrate that the beta function is a cubic polynomial in x6 at this order in 1/N, and compute the coefficients of the cubic and quadratic terms as a function of the ’t Hooft coupling. We conjecture that flows governed by this leading large N beta function have three fixed points for x6 at every non-zero value of the ’t Hooft coupling, implying the existence of three distinct regular bosonic and three distinct dual critical fermionic conformal fixed points, at every value of the ’t Hooft coupling. We analyze the phase structure of these fixed point theories at zero temperature. We also construct dual pairs of large N fine-tuned renormalization group flows from supersymmetric mathcal{N}=2 Chern-Simons-matter theories, such that one of the flows ends up in the IR at a regular boson theory while its dual partner flows to a critical fermion theory. This construction suggests that the duality between these theories persists at finite N, at least when N is large.

Bose-Fermi Chern-Simons dualities in the Higgsed phase

It has been conjectured that fermions minimally coupled to a Chern-Simons gauge field define a conformal field theory (CFT) that is level-rank dual to Chern-Simons gauged Wilson-Fisher Bosons. The CFTs in question admit relevant deformations parametrized by a real mass. When the mass deformation is positive, the duality of the two deformed theories has previously been checked in detail in the large N limit by comparing explicit all orders results on both sides of the duality. In this paper we perform a similar check for the case of negative mass deformations. In this case the bosonic field condenses triggering the Higgs mechanism. The effective excitations in this phase are massive W bosons. By summing all leading large N graphs involving these W bosons we find an all orders (in the ’t Hooft coupling) result for the thermal free energy of the bosonic theory in the condensed phase. Our final answer perfectly matches the previously obtained fermionic free energy under the conjectured duality map.

Boson–fermion duality in a gravitational background

We study the 2+1 dimensional boson–fermion duality in the presence of background curvature and electromagnetic fields. The main players are, on the one hand, a massive complex |ϕ|4 scalar field coupled to a U(1) Maxwell–Chern–Simons gauge field at level 1, representing a relativistic composite boson with one unit of attached flux, and on the other hand, a massive Dirac fermion. We show that, in a curved background and at the level of the partition function, the relativistic composite boson, in the infinite coupling limit, is dual to a short-range interacting Dirac fermion. The coupling to the gravitational spin connection arises naturally from the spin factors of the Wilson loop in the Chern–Simons theory. A non-minimal coupling to the scalar curvature is included on the bosonic side in order to obtain agreement between partition functions. Although an explicit Lagrangian expression for the fermionic interactions is not obtained, their short-range nature constrains them to be irrelevant, which protects the duality in its strong interpretation as an exact mapping at the IR fixed point between a Wilson–Fisher–Chern–Simons complex scalar and a free Dirac fermion. We also show that, even away from the IR, keeping the |ϕ|4 term is of key importance as it provides the short-range bosonic interactions necessary to prevent intersections of worldlines in the path integral, thus forbidding unknotting of knots and ensuring preservation of the worldline topologies.

Topological phase transition of the anisotropic XY model with Dzyaloshinskii-Moriya interaction

Within the real space renormalization group we obtain the phase portrait of the anisotropic quantum XY model on square lattice in presence of Dzyaloshinskii-Moriya (DM) interaction. The model is characterized by two parameters, $\lambda$ corresponding to XY anisotropy, and $D$ corresponding to the strength of DM interaction. The flow portrait of the model is governed by two global Ising-Kitaev attractors at $(\lambda=\pm1,D=0)$ and a repeller line, $\lambda=0$. Renormalization flow of concurrence suggests that the $\lambda=0$ line corresponds to a topological phase transition. The gap starts at zero on this repeller line corresponding to super-fluid phase of underlying bosons; and flows towards a finite value at the Ising-Kitaev points. At these two fixed points the spin fields become purely classical, and hence the resulting Ising degeneracy can be interpreted as topological degeneracy of dual degrees of freedom. The state of affairs at the Ising-Kitaev fixed point is consistent with the picture of a p-wave pairing of strength $\lambda$ of Jordan-Wigner fermions coupled with Chern-Simons gauge fields.

Chern-Simons fermionization approach to two-dimensional quantum magnets: Implications for antiferromagnetic magnons and unconventional quantum phase transitions

We develop an approach to describe antiferromagnetic magnons on a bipartite lattice supporting the N\'{e}el state using fractionalized degrees of freedom typically inherent to quantum spin liquids. In particular we consider a long-range magnetically ordered state of interacting two-dimensional quantum spin$-1/2$ models using the Chern-Simons (CS) fermion representation of interacting spins. The interaction leads to Cooper instability and pairing of CS fermions, and to CS superconductivity which spontaneously violates the continuous $\mathrm{U}(1)$ symmetry generating a linearly-dispersing gapless Nambu-Goldstone mode due to phase fluctuations. We evaluate this mode and show that it is in high-precision agreement with magnons of the corresponding N\'{e}el antiferromagnet irrespective to the lattice symmetry. Using the fermion formulation of a system with competing interactions, we show that the frustration gives raise to nontrivial long-range four, six, and higher-leg interaction vertices mediated by the CS gauge field, which are responsible for restoring of the continuous symmetry at sufficiently strong frustration. We identify these new interaction vertices and discuss their implications to unconventional phase transitions. We also apply the proposed theory to a model of anyons that can be tuned continuously from fermions to bosons.

Global Energy Solution to the Schrödinger Equation Coupled with the Chern-Simons Gauge and Neutral Field

We study the Cauchy problem of the Chern-Simons-Schrödinger equations with a neutral field, under the Coulomb gauge condition, in energy space H1(R2). We prove the uniqueness of a solution by using the Gagliardo-Nirenberg inequality with the specific constant. To obtain a global solution, we show the conservation of total energy and find a bound for the nondefinite term.

1D anyons in relativistic field theory

Abstract We study relativistic anyon field theory in 1+1 dimensions. While (2+1)-dimensional anyon fields are equivalent to boson or fermion fields coupled with the Chern–Simons gauge fields, (1+1)-dimensional anyon fields are equivalent to boson or fermion fields with many-body interaction. We derive the path integral representation and perform a lattice Monte Carlo simulation.

Non-Abelian fermionization and fractional quantum Hall transitions

There has been a recent surge of interest in dualities relating theories of Chern-Simons gauge fields coupled to either bosons or fermions within the condensed matter community, particularly in the context of topological insulators and the half-filled Landau level. Here, we study the application of one such duality to the long-standing problem of quantum Hall inter-plateaux transitions. The key motivating experimental observations are the anomalously large value of the correlation length exponent $\nu \approx 2.3$ and that $\nu$ is observed to be super-universal, i.e., the same in the vicinity of distinct critical points. Duality motivates effective descriptions for a fractional quantum Hall plateau transition involving a Chern-Simons field with $U(N_c)$ gauge group coupled to $N_f = 1$ fermion. We study one class of theories in a controlled limit where $N_f \gg N_c$ and calculate $\nu$ to leading non-trivial order in the absence of disorder. Although these theories do not yield an anomalously large exponent $\nu$ within the large $N_f \gg N_c$ expansion, they do offer a new parameter space of theories that is apparently different from prior works involving abelian Chern-Simons gauge fields.

Chern–Simons theories with fundamental matter: A brief review of large N results including Fermi–Bose duality and the S-matrix

We begin with a few words about Salam’s contribution to the growth of String Theory in India. In the technical talk we review results in [Formula: see text] Chern–Simons plus vector matter theories in 2[Formula: see text]+[Formula: see text]1 dim in the large [Formula: see text] limit. The dressing of charged matter by Chern–Simons gauge fields leads to anyons that interpolate between fermions and bosons and lead to a duality symmetry between fermionic and bosonic theories. The S-matrix (defined in the large [Formula: see text] limit) besides exhibiting this duality, also exhibits novel properties due to the presence of anyons. The S-matrix is not analytic, like in Aharonov–Bohm scattering, and satisfies modified crossing symmetry relations.

Equivalence and nonexistence of standing waves for coupled Schrodinger equations with Chern-Simons gauge fields

This paper is devoted to the study of standing waves for so-called $N=2$ supersymmetric Chern--Simons--Schrodinger equations, a coupled system of Schr\odinger equations in which Chern--Simons gauge fields are incorporated. We show that there is no nontrivial standing wave to the $N=2$ supersymmetric Chern--Simons--Schrodinger equations when the coupling constants are less than critical numbers. We also prove that static $N=2$ supersymmetric Chern--Simons--Schrodinger equations are equivalent to their first order self-dual system when the coupling constants are critical.