Simplest phonons and pseudo-phonons in field theory

Self Cite

We study a holographic model where translations are both spontaneously and explicitly broken, leading to the presence of (pseudo)-phonons in the spectrum. The weak explicit breaking is due to two independent mechanisms: a small source for the condensate itself and additional linearly space-dependent marginal operators. The low energy dynamics of the model is described by Wigner crystal hydrodynamics. In absence of a source for the condensate, the phonons remain gapless, but momentum is relaxed. Turning on a source for the condensate damps and pins the phonons. Finally, we verify that the universal relation between the phonon damping rate, mass and diffusivity reported in [1] continues to hold in this model for weak enough explicit breaking.1 These holographic homogeneous models inspired analogous constructions [20] which account for the translation-breaking dynamics in a purely field-theoretical context. For a generalization of such constructions to inhomogeneous case see [21]. 2 The pinning frequency can also be written more intuitively as ω o = c ⊥ k o with k o ≡ m the inverse length scale defined by the phonon mass and c ⊥ ≡ G/χ P P the shear sound velocity. 10 Based on private communication with the authors of [46] and [48].

supporting

confidence: 66%

“…1 These holographic homogeneous models inspired analogous constructions [20] which account for the translation-breaking dynamics in a purely field-theoretical context. For a generalization of such constructions to inhomogeneous case see [21].…”

mentioning

confidence: 99%

Gapless and gapped holographic phonons

Amoretti

Areán

Goutéraux

et al. 2020

Self Cite

“…See[32,34,35,[53][54][55][56][57][58] for other studies of the interplay of spontaneous and explicit breaking of translations in holography and field theory.…”

mentioning

confidence: 99%

A unified description of translational symmetry breaking in holography

Ammon

Baggioli

Alba

2019

131

We provide a complete and unified description of translational symmetry breaking in a simple holographic model. In particular, we focus on the distinction and the interplay between explicit and spontaneous breaking. We consider a class of holographic massive gravity models which allow to range continuously from one situation to the other. We study the collective degrees of freedom, the electric AC conductivity and the shear correlator in function of the explicit and spontaneous scales. We show the possibility of having a sound-to-diffusion crossover for the transverse phonons. Within our model, we verify the validity of the Gell-Mann-Oakes-Renner relation. Despite of strong evidence for the absence of any standard dislocation induced phase relaxation mechanism, we identify a novel relaxation scale controlled by the ratio between the explicit and spontaneous breaking scales. Finally, in the pseudospontaneous limit, we prove analytically the relation, which has been discussed in the literature, between this novel relaxation scale, the mass of the pseudo-phonons and the Goldstone diffusivity. Our numerical data confirms this analytic result.

“…However, it does not allow to study the transition between the two phases. (Pseudo)-spontaneous breaking patterns of translational symmetry have been studied recently in holography and field theory frameworks [9][10][11][12][13][14][15][16][17][18][19][20]. In the holographic context, the focus has mainly been on the zero momentum optical conductivity.…”

Section: Introductionmentioning

confidence: 99%

Density response of holographic metallic IR fixed points with translational pseudo-spontaneous symmetry breaking

Romero-Bermúdez

2019

The density response of charged liquids contains a collective excitation known as the plasmon. In holographic systems with translational invariance the origin of this collective excitation is traced back to the presence of zero-sound. Using a holographic model in which translational symmetry is broken pseudo-spontaneously, we show the density response is not dominated by a single isolated mode at low momentum and temperature. As a consequence, the density response contains a broad asymmetric peak with an attenuation which does not increase monotonically with momentum and temperature.