118336021
Confinement Phase in Carbon-Nanotubes and the Extended Massive Schwinger Model
Carbon nanotube with electric fluxes confined in one dimension is studied. We show that a Coulomb interaction \propto |x| leads to a confinement phase with many properties similar to QCD in 4D. Low-energy physics is described by the massive Schwinger model with multi-species fermions labeled by the band and valley indices. We propose two means to detect this state. One is through an optical measurement of the exciton spectrum, which has been calculated via the 't Hooft-Berknoff equation with the light-front field theory. We show that the Gell-Mann-Oakes-Renner relation is satisfied by a dark exciton. The second is the nonlinear transport which is related to Coleman's "half-asymptotic" state.
119210365
Floquet Majorana Edge Mode and Non-Abelian Anyons in a Driven Kitaev Model
We theoretically study laser driven nonequilibrium states in the Kitaev honeycomb model with a magnetoelectric cross coupling. We show that a topological spin liquid with a gapless chiral edge mode emerges when we apply an elliptically or circularly polarized laser. This is a strongly correlated quantum spin version of the Floquet topological insulator. In the topological phase, the edge mode is made from Majorana fermions and the bulk has gapped non-Abelian anyon excitations.
116986876
Strong field physics in condensed matter
There are deep similarities between non-linear QFT studied in high-energy and non-equilibrium physics in condensed matter. Ideas such as the Schwinger mechanism and the Volkov state are deeply related to non-linear transport and photovoltaic Hall effect in condensed matter. Here, we give a review on these relations.
118504703
Magnetic instability in AdS/CFT: Schwinger effect and Euler-Heisenberg Lagrangian of supersymmetric QCD
A bstractTo reveal the Schwinger effect for quarks, i.e., pair creation process of quarks and antiquarks, we derive the vacuum decay rate at strong coupling using AdS/CFT correspondence. Magnetic fields, in addition to the electric field responsible for the pair creation, causes prominent effects on the rate, and is important also in experiments such as RHIC/LHC heavy ion collisions. In this paper, through the gravity dual we obtain the full Euler-Heisenberg Lagrangian of $ \mathcal{N} $ = 2 supersymmetric QCD and study the Schwinger mechanism with not only a constant electric field but also a constant magnetic field as external fields. We determine the quark mass and temperature dependence of the Lagrangian. In sharp contrast to the zero magnetic field case, we find that the imaginary part, and thus the vacuum decay rate, diverges in the massless zero-temperature limit. This may be related to a strong instability of the QCD vacuum in strong magnetic fields. The real part of the Lagrangian serves as a generating function for non-linear electro-magnetic responses, and is found such that the Cotton-Mouton effect vanishes. Interestingly, our results of the Schwinger/Cotton-Mouton effects coincide precisely with those of $ \mathcal{N} $ = 2 supersymmetric QED.
119301422
Restricted phase-space approximation in real-time stochastic quantization
Abstract We perform and extend real-time numerical simulation of a low-dimensional scalar field theory or a quantum mechanical system using stochastic quantization. After a brief review of the quantization method and the complex Langevin dynamics, we calculate the propagator and make a comparison with analytical results. This is a first step toward general applications, and we focus only on the vacuum properties of the theory; this enables us to handle the boundary condition with the i ϵ prescription in frequency space. While we can control stability of the numerical simulation for any coupling strength, our results turn out to flow into an unphysical fixed-point, which is qualitatively understood from the corresponding Fokker–Planck equation. We propose a simple truncation scheme, “restricted phase-space approximation”, to avoid the unphysical fixed-point. With this method, we obtain stable results at reasonably good accuracy. Finally we give a short discussion on the closed-time path formalism and demonstrate the direct computation of the vacuum expectation value not with the i ϵ prescription but from an explicit construction of the Feynman kernel.
120164788
Nonlinear doublon production in a Mott insulator: Landau-Dykhne method applied to an integrable model
Doublon-hole pair production which takes place during dielectric breakdown in a Mott insulator subject to a strong laser or a static electric field is studied in the one-dimensional Hubbard model. Two nonlinear effects cause the excitation, i.e., multi-photon absorption and quantum tunneling. Keldysh crossover between the two mechanisms occurs as the field strength and photon energy is changed. The calculation is done analytically by the Landau-Dykhne method in combination with the Bethe ansatz solution and the results are compared with those of the time dependent density matrix renormalization group. Using this method, we calculate distribution function of the generated doublon-hole pairs and show that it drastically changes as we cross the Keldysh crossover line. After calculating the tunneling threshold for several representative one-dimensional Mott insulators, possible experimental tests of the theory is proposed such as angle resolved photoemission spectroscopy of the upper Hubbard band in the quantum tunneling regime. We also discuss the relation of the present theory with a many-body extension of electron-positron pair production in nonlinear quantum electrodynamics known as the Schwinger mechanism.
16063796
Investigating the Cosmic-ray Ionization Rate Near the Supernova Remnant IC 443 through H+ 3 Observations
Observational and theoretical evidence suggests that high-energy Galactic cosmic rays are primarily accelerated by supernova remnants. If also true for low-energy cosmic rays, the ionization rate near a supernova remnant should be higher than in the general Galactic interstellar medium (ISM). We have searched for H^(+)_(3) absorption features in six sight lines which pass through molecular material near IC 443—a well-studied case of a supernova remnant interacting with its surrounding molecular material—for the purpose of inferring the cosmic-ray ionization rate in the region. In two of the sight lines (toward ALS 8828 and HD 254577) we find large H^(+)_(3) column densities, N(H^(+)_(3)) ≈ 3 × 10^(14) cm^(–2), and deduce ionization rates of ζ2 ≈ 2 × 10^(–15) s^(–1), about five times larger than inferred toward average diffuse molecular cloud sight lines. However, the 3σ upper limits found for the other four sight lines are consistent with typical Galactic values. This wide range of ionization rates is likely the result of particle acceleration and propagation effects, which predict that the cosmic-ray spectrum and thus ionization rate should vary in and around the remnant. While we cannot determine if the H^(+)_(3) absorption arises in post-shock (interior) or pre-shock (exterior) gas, the large inferred ionization rates suggest that IC 443 is in fact accelerating a large population of low-energy cosmic rays. Still, it is unclear whether this population can propagate far enough into the ISM to account for the ionization rate inferred in diffuse Galactic sight lines.
12286403
HOT AND DIFFUSE CLOUDS NEAR THE GALACTIC CENTER PROBED BY METASTABLE H~3^+
Using an absorption line from the metastable (J ; K) ¼ (3; 3) level of H þ together with other lines of H þ and CO observed along several sight lines, we have discovered a vast amount of high-temperature (T � 250 K) and lowdensity (n � 100 cm � 3 ) gas with a large velocity dispersion in the central molecular zone (CMZ) of the Galaxy, i.e., within 200 pc of the center. Approximately three-fourths of the H þ along the line of sight to the brightest source we observed, the Quintuplet object GCS 3-2, is inferred to be in the CMZ, with the remaining H þ located in intervening spiral arms. About half of the H þ in the CMZ has velocities near �� 100 km s � 1 , indicating that it is associated with the 180 pc radius expanding molecular ring, which approximately forms the outer boundary of the CMZ. The other half,withvelocitiesof �� 50and � 0kms � 1 ,isprobablyclosertothecenter.COisnotveryabundantintheseclouds. Hot and diffuse gas in which the (3, 3) level is populated was not detected toward several dense clouds and diffuse clouds intheGalacticdiskwhere largecolumndensities ofcolder H þ have beenreportedpreviously.Thus,thenewly discovered environment appears to be unique to the CMZ. The large observed H þ column densities in the CMZ suggestanionizationratemuchhigher thaninthediffuseinterstellarmediumintheGalacticdisk.Ourfindingthatthe H þ in the CMZ is almost entirely in diffuse clouds indicates that the reported volume filling factor (f � 0:1) for n � 10 4 cm � 3 clouds in the CMZ is an overestimate by at least an order of magnitude. Subject headings: astrochemistry — Galaxy: center — ISM: clouds — ISM: molecules — molecular processes — radiation mechanisms: nonthermal