Distinguishingk-defects from their canonical twins

Abstract

We study k-defects-topological defects in theories with more than two derivatives and second-order equations of motion-and describe some striking ways in which these defects both resemble and differ from their analogues in canonical scalar field theories. We show that, for some models, the homotopy structure of the vacuum manifold is insufficient to establish the existence of k-defects, in contrast to the canonical case. These results also constrain certain families of Dirac-Born-Infeld instanton solutions in the 4-dimensional effective theory. We then describe a class of k-defect solutions, which we dub ''doppelgängers,'' that precisely match the field profile and energy density of their canonical scalar field theory counterparts. We give a complete characterization of Lagrangians which admit doppelgänger domain walls. By numerically computing the fluctuation eigenmodes about domain wall solutions, we find different spectra for doppelgängers and canonical walls, allowing us to distinguish between k-defects and the canonical walls they mimic. We search for doppelgängers for cosmic strings by numerically constructing solutions of Dirac-Born-Infeld and canonical scalar field theories. Despite investigating several examples, we are unable to find doppelgänger cosmic strings, hence the existence of doppelgängers for defects with codimension >1 remains an open question. We study k-defects-topological defects in theories with more than two derivatives and second-order equations of motion-and describe some striking ways in which these defects both resemble and differ from their analogues in canonical scalar field theories. We show that, for some models, the homotopy structure of the vacuum manifold is insufficient to establish the existence of k-defects, in contrast to the canonical case. These results also constrain certain families of Dirac-Born-Infeld instanton solutions in the 4-dimensional effective theory. We then describe a class of k-defect solutions, which we dub ''doppelgängers,'' that precisely match the field profile and energy density of their canonical scalar field theory counterparts. We give a complete characterization of Lagrangians which admit doppelgänger domain walls. By numerically computing the fluctuation eigenmodes about domain wall solutions, we find different spectra for doppelgängers and canonical walls, allowing us to distinguish between k-defects and the canonical walls they mimic. We search for doppelgängers for cosmic strings by numerically constructing solutions of Dirac-Born-Infeld and canonical scalar field theories. Despite investigating several examples, we are unable to find doppelgänger cosmic strings, hence the existence of doppelgängers for defects with codimension >1 remains an open question. Disciplines Physical Sciences and Mathematics | Physics

Beyond the cosmological standard model

“…A postivie energy theorem for P (X, φ) theories coupled to Einstein gravity has been proved in [451,452]. Futher, P (X, φ) models have been supersymmetrized [453,454], and topological defects and solitons are studied in [455][456][457][458][459][460][461][462][463][464]. Analyses of screening in these models can be found in [197-200, 465, 466], along with studies of large-scale sctructure [467,468].…”

Kink-antikink collisions for twin models

“…Also, numerical analysis discussing their eigenmodes can be found in two different ways in Refs. [16,23].…”

“…a class of topological defects with the same scalar field profiles and energy densities [16]. For some recent results on this subject, see [17][18][19].…”

Stability and superluminality of spherical DBI Galileon solutions

“…The Dirac-Born-Infeld (DBI) action, which describes the dynamics of a brane embedded in a higher dimensional spacetime, has provided an important setting within which to study inflation [1,2], late-time cosmic acceleration [3], tunneling [4], and exotic topological defects [5][6][7][8][9]. The DBI action has been extensively studied in recent years, and its rather special properties are now well-understood.…”