scholarly journals Spontaneous breaking of continuous translational invariance

2012 ◽  
Vol 85 (8) ◽  
Author(s):  
Haruki Watanabe ◽  
Tomáš Brauner
Keyword(s):  
Spontaneous Breaking ◽  
Translational Invariance

scholarly journals On the universality of AdS2 diffusion bounds and the breakdown of linearized hydrodynamics

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Ning Wu ◽  
Matteo Baggioli ◽  
Wei-Jia Li
Keyword(s):  
Quantum Chaos ◽  
Short Note ◽  
Diffusion Constant ◽  
Coupled Systems ◽  
Recent Analysis ◽  
Spontaneous Breaking ◽  
Hydrodynamic Mode ◽  
Translational Invariance ◽  
Strongly Coupled ◽  
Track Record

Abstract The chase of universal bounds on diffusivities in strongly coupled systems and holographic models has a long track record. The identification of a universal velocity scale, independent of the presence of well-defined quasiparticle excitations, is one of the major challenges of this program. A recent analysis, valid for emergent IR fixed points exhibiting local quantum criticality, and dual to IR AdS2 geometries, suggests to identify such a velocity using the time and length scales at which hydrodynamics breaks down — the equilibration velocity. The latter relates to the radius of convergence of the hydrodynamic expansion and it is extracted from a collision between a hydrodynamic diffusive mode and a non-hydrodynamic mode associated to the IR AdS2 region. In this short note, we confirm this picture for holographic systems displaying the spontaneous breaking of translational invariance. Moreover, we find that, at zero temperature, the lower bound set by quantum chaos and the upper one defined by causality and hydrodynamics exactly coincide, determining uniquely the diffusion constant. Finally, we comment on the meaning and universality of this newly proposed prescription.

Nonlinear theory of modulated standing waves; domain walls, kinks and breathers

1993 ◽  
Vol 440 (1908) ◽  
pp. 135-148 ◽  
Keyword(s):  
Domain Wall ◽  
Nonlinear Theory ◽  
Toda Lattice ◽  
Domain Walls ◽  
Standing Waves ◽  
Wave Number ◽  
One Dimension ◽  
Spontaneous Breaking ◽  
Translational Invariance ◽  
Localized Solutions

A nonlinear theory of modulated standing waves is developed in one dimension. The existence of various localized solutions is elucidated. These include: domain walls , which characterize the transition between regions of different wave number, kinks , which describe a shift in the phase of the oscillation, and lower cut-off breathers . All of these states correspond to a spontaneous breaking of translational invariance, while the domain wall in addition represents a broken parity. Except for the breathers, the modulational equations that describe these states take a form that differs from the sine-Gordon, nonlinear Schrödinger, Toda lattice and Korteweg de Vries equations. In addition to the hamiltonian limit, the case of damped parametrically driven motion is also discussed.

Thermodynamic Green’s Functions and Spectral Structure

2018 ◽  
Author(s):  
Norman J. Morgenstern Horing
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Green's Functions ◽  
Green’S Functions ◽  
Spectral Weight ◽  
Statistical Thermodynamic ◽  
Spectral Structure ◽  
Imaginary Time ◽  
Translational Invariance ◽  
The One

Multiparticle thermodynamic Green’s functions, defined in terms of grand canonical ensemble averages of time-ordered products of creation and annihilation operators, are interpreted as tracing the amplitude for time-developing correlated interacting particle motions taking place in the background of a thermal ensemble. Under equilibrium conditions, time-translational invariance permits the one-particle thermal Green’s function to be represented in terms of a single frequency, leading to a Lehmann spectral representation whose frequency poles describe the energy spectrum. This Green’s function has finite values for both t>t′ and t<t′ (unlike retarded Green’s functions), and the two parts G1> and G1< (respectively) obey a simple proportionality relation that facilitates the introduction of a spectral weight function: It is also interpreted in terms of a periodicity/antiperiodicity property of a modified Green’s function in imaginary time capable of a Fourier series representation with imaginary (Matsubara) frequencies. The analytic continuation from imaginary time to real time is discussed, as are related commutator/anticommutator functions, also retarded/advanced Green’s functions, and the spectral weight sum rule is derived. Statistical thermodynamic information is shown to be embedded in physical features of the one- and two-particle thermodynamic Green’s functions.

scholarly journals Impurity induced scale-free localization

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Linhu Li ◽  
Ching Hua Lee ◽  
Jiangbin Gong
Keyword(s):  
Boundary Conditions ◽  
Skin Effect ◽  
Reciprocal Lattice ◽  
Periodic Boundary Conditions ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Translational Invariance ◽  
Scale Free ◽  
Special Cases ◽  
Simulation Results

AbstractNon-Hermitian systems have been shown to have a dramatic sensitivity to their boundary conditions. In particular, the non-Hermitian skin effect induces collective boundary localization upon turning off boundary coupling, a feature very distinct from that under periodic boundary conditions. Here we develop a full framework for non-Hermitian impurity physics in a non-reciprocal lattice, with periodic/open boundary conditions and even their interpolations being special cases across a whole range of boundary impurity strengths. We uncover steady states with scale-free localization along or even against the direction of non-reciprocity in various impurity strength regimes. Also present are Bloch-like states that survive albeit broken translational invariance. We further explore the co-existence of non-Hermitian skin effect and scale-free localization, where even qualitative aspects of the system’s spectrum can be extremely sensitive to impurity strength. Specific circuit setups are also proposed for experimentally detecting the scale-free accumulation, with simulation results confirming our main findings.

scholarly journals Symmetry breaking at high temperatures in large N gauge theories

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Soumyadeep Chaudhuri ◽  
Eliezer Rabinovici
Keyword(s):  
Fixed Point ◽  
Phase Transitions ◽  
Symmetry Breaking ◽  
High Temperatures ◽  
Gauge Theories ◽  
Scalar Fields ◽  
Temperature Limit ◽  
Spontaneous Breaking ◽  
Critical Temperatures ◽  
Weakly Coupled

Abstract Considering marginally relevant and relevant deformations of the weakly coupled (3 + 1)-dimensional large N conformal gauge theories introduced in [1], we study the patterns of phase transitions in these systems that lead to a symmetry-broken phase in the high temperature limit. These deformations involve only the scalar fields in the models. The marginally relevant deformations are obtained by varying certain double trace quartic couplings between the scalar fields. The relevant deformations, on the other hand, are obtained by adding masses to the scalar fields while keeping all the couplings frozen at their fixed point values. At the N → ∞ limit, the RG flows triggered by these deformations approach the aforementioned weakly coupled CFTs in the UV regime. These UV fixed points lie on a conformal manifold with the shape of a circle in the space of couplings. As shown in [1], in certain parameter regimes a subset of points on this manifold exhibits thermal order characterized by the spontaneous breaking of a global ℤ2 or U(1) symmetry and Higgsing of a subset of gauge bosons at all nonzero temperatures. We show that the RG flows triggered by the marginally relevant deformations lead to a weakly coupled IR fixed point which lacks the thermal order. Thus, the systems defined by these RG flows undergo a transition from a disordered phase at low temperatures to an ordered phase at high temperatures. This provides examples of both inverse symmetry breaking and symmetry nonrestoration. For the relevant deformations, we demonstrate that a variety of phase transitions are possible depending on the signs and magnitudes of the squares of the masses added to the scalar fields. Using thermal perturbation theory, we derive the approximate values of the critical temperatures for all these phase transitions. All the results are obtained at the N → ∞ limit. Most of them are found in a reliable weak coupling regime and for others we present qualitative arguments.

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