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(174) Production(s) de l'année 2021


Polariton topological transition effects on radiative heat transfer
Auteur(s): Zhou Chenglong, Wu Xiaohu, Zhang Yong, Yi Hingliang, Antezza M.
(Article) Publié:
Physical Review B Condensed Matter (19781997), vol. 103 p.155404 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03191119_v1
DOI: 10.1103/PhysRevB.103.155404
Exporter : BibTex  endNote
Résumé: Twisted twodimensional bilayer anisotropy materials exhibit many exotic physical phenomena. Manipulating the “twist angle” between the two layers enables the hybridization phenomenon of polaritons, resulting in fine control of the dispersion engineering of the polaritons in these structures. Here, combined with the hybridization phenomenon of anisotropy polaritons, we study theoretically the nearfield radiative heat transfer (NFRHT) between two twisted hyperbolic systems. These two twisted hyperbolic systems are mirror images of each other. Each twisted hyperbolic system is composed of two graphene gratings, where there is an angle φ between these two graphene gratings. By analyzing the photonic transmission coefficient as well as the plasmon dispersion relation of the twisted hyperbolic system, we prove the enhancement effect of the topological transitions of the surface state at a special angle [from open (hyperbolic) to closed (elliptical) contours] on radiative heat transfer. Meanwhile the role of the thickness of dielectric spacer and vacuum gap on the manipulating the topological transitions of the surface state and the NFRHT are also discussed. We predict the hysteresis effect of topological transitions at a larger vacuum gap, and demonstrate that as the thickness of the dielectric spacer increases, the transition from the enhancement effect of heat transfer caused by the twisted hyperbolic system to a suppression.



Coulomb branch of N=4 SYM and dilatonic scions in supergravity
Auteur(s): Elander D., Piai Maurizio, Roughley John
(Article) Publié:
Phys.rev.d, vol. 104 p.046003 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03186214_v1
Ref Arxiv: 2103.06721
Ref INSPIRE: 1851112
DOI: 10.1103/PhysRevD.104.046003
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: We find a parametrically light dilaton in special confining theories in three dimensions. Their duals form what we call a scion of solutions to the supergravity associated with the large$N$ limit of the Coulomb branch of the $\mathcal{N}=4$ SuperYangMills theory. The supergravity description contains one scalar with bulk mass that saturates the BreitenlohnerFreedman unitarity bound. The new solutions are defined within supergravity, they break supersymmetry and scale invariance, and one dimension is compactified on a shrinking circle, yet they are completely regular. An approximate dilaton appears in the spectrum of background fluctuations (or composite states in the confining theory), and becomes parametrically light along a metastable portion of the scion of new supergravity solutions, in close proximity of a tachyonic instability. A firstorder phase transition separates stable backgrounds, for which the approximate dilaton is not parametrically light, from metastable and unstable backgrounds, for which the dilaton becomes parametrically light, and eventually tachyonic.



Miles' mechanism for generating surface water waves by wind, in finite water depth and subject to constant vorticity flow
Auteur(s): Kern N., Chaubet C., Kraenkel Roberto, Manna M.
(Document sans référence bibliographique) Texte intégral en Openaccess :
Ref HAL: hal03184640_v1
Ref Arxiv: 2102.13214
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: The Miles theory of wave amplification by wind is extended to the case of finite depth h and a shear flow with (constant) vorticity {\Omega}. Vorticity is characterised through the nondimensional parameter {\nu} = {\Omega} U_1 /g, where g the gravitational acceleration, U_1 a characteristic wind velocity and k the wavenumber. The notion of 'wave age' is generalised to account for the effect of vorticity. Several widely used growth rates are derived analytically from the dispersion relation of the wind/water interface, and their dependence on both water depth and vorticity is derived and discussed. Vorticity is seen to shift the maximum wave age, similar to what was previously known to be the effect of water depth. At the same time, a novel effect arises and the growth coefficients, at identical wave age and depth, are shown to experience a net increase or decrease according to the shear gradient in the water flow.



Twospecies TASEP model: from a simple description to intermittency and travelling traffic jams
Auteur(s): Bonnin Pierre, Stansfield Ian, Romano M. Carmen, Kern N.
(Document sans référence bibliographique) Texte intégral en Openaccess :
Ref HAL: hal03184622_v1
Ref Arxiv: 2102.02486
Ref. & Cit.: NASA ADS
Exporter : BibTex  endNote
Résumé: We extend the paradigmatic and versatile TASEP (Totally Asymmetric Simple Exclusion Process) for stochastic 1d transport to allow for two different particle species, each having specific entry and exit rates. We offer a complete meanfield analysis, including a phase diagram, by mapping this model onto an effective onespecies TASEP. Stochastic simulations confirm the results, but indicate deviations when the particle species have very different exit rates. We illustrate that this is due to a phenomenon of intermittency, and formulate a refined 'intermittent' meanfield (iMF) theory for this regime. We discuss how nonstationary effects may further enrich the phenomenology.



Negative cosmological constant in the dark sector?
Auteur(s): Calderon R., Gannouji Radouane, L'Huillier Benjamin, Polarski D.
(Article) Publié:
Physical Review D, vol. 103 p.023526 (2021)
Texte intégral en Openaccess :
Ref HAL: hal03184607_v1
DOI: 10.1103/PhysRevD.103.023526
WoS: WOS:000609014700004
Exporter : BibTex  endNote
Résumé: We consider the possibility that the dark sector of our Universe contains a negative cosmological constant dubbed λ. For such models to be viable, the dark sector should contain an additional component responsible for the latetime accelerated expansion rate (X). We explore the departure of the expansion history of these models from the concordanceΛ cold dark matter (ΛCDM) model. For a large class of our models, the accelerated expansion is transient with a nontrivial dependence on the model parameters. All models with wX>−1 will eventually contract and we derive an analytical expression for the scale factor a(t) in the neighborhood of its maximal value. We find also the scale factor for models ending in a Big Rip in the regime where dustlike matter density is negligible compared to λ. We address further the viability of such models, in particular when a high H0 is taken into account. While we find no decisive evidence for a nonzero λ, the best models are obtained with a phantom behavior on redshifts z≳1 with a higher evidence for nonzero λ. An observed value for h substantially higher than 0.70 would be a decisive test of their viability.



Microspheres viscous drag at a deformed fluid interface: particle's weight and electrical charges effects
Auteur(s): Ben'mbarek Nadia, Aschi Adel, Blanc C., Nobili M.
(Article) Publié:
European Physical Journal E, vol. 44 p.26 (2021)
Ref HAL: hal03184308_v1
DOI: 10.1140/epje/s1018902100041w
WoS: WOS:000627367000001
Exporter : BibTex  endNote
Résumé: When a microparticle is trapped at a fluid interface, particle's electrical charge and weight combine to deform the interface. Such deformation is expected to affect the particle diffusion via hydrodynamics boundary conditions. Using available models of particleinduced electrostatic deformation of the interface and particle dynamics at the interface, we are able to analytically predict particle diffusion coefficient values in a large range of particle's contact angle and size. This might offer a solid background of numerical values to compare with for future experimental studies in the field of particle diffusion at a fluid interface.



Turning Rubber into a Glass: Mechanical Reinforcement by Microphase Separation
Auteur(s): Tress Martin, Ge Sirui, Xing Kunyue, Cao Pengfei, Saito Tomonori, Genix A.C., Sokolov Alexei p.
(Article) Publié:
Acs Macro Letters, vol. 10 p.197202 (2021)
Ref HAL: hal03181032_v1
DOI: 10.1021/acsmacrolett.0c00778
WoS: WOS:000620928600005
Exporter : BibTex  endNote
Résumé: Supramolecular associations provide a promising route to functional materials with properties such as selfhealing, easy recyclability or extraordinary mechanical strength and toughness. The latter benefit especially from the transient character of the formed network, which enables dissipation of energy as well as regeneration of the internal structures. However, recent investigations revealed intrinsic limitations in the achievable mechanical enhancement. This manuscript presents studies of a set of telechelic polymers with hydrogenbonding chain ends exhibiting an extraordinarily high, almost glasslike, rubbery plateau. This is ascribed to the segregation of the associative ends into clusters and formation of an interfacial layer surrounding these clusters. An approach adopted from the field of polymer nanocomposites provides a quantitative description of the data and reveals the strongly altered mechanical properties of the polymer in the interfacial layer. These results demonstrate how employing phase separating dynamic bonds can lead to the creation of highperformance materials.
