Impact of string and monopole-type junctions on domain wall dynamics: Implications for dark energyL. Sousa, P. P. AvelinoAbstractWe investigate the potential role of string and monopole-type junctions in the frustration of domain wall networks using a velocity-dependent one-scale model for the characteristic velocity, v, and the characteristic length, L  , of the network. We show that, except for very special network configurations, v2≲(HL)2≲(ρσ+ρμ)/ρm$v2≲(HL)2≲(ρσ+ρμ)/ρm$ where H   is the Hubble parameter and ρσ$ρσ$, ρμ$ρμ$ and ρm$ρm$ are the average density of domain walls, strings and monopole-type junctions. We further show that if domain walls are to provide a significant contribution to the dark energy without generating exceedingly large CMB temperature fluctuations then, at the present time, the network must have a characteristic length and a characteristic velocity $v0≲10−5Ωσ0−2/3$ where Ωσ0=ρσ0/ρc0$Ωσ0=ρσ0/ρc0$ and ρc$ρc$ is the critical density. In order to satisfy these constraints with Ωσ0∼1$Ωσ0∼1$, ρm0$ρm0$ would have to be at least 10 orders of magnitude larger than ρσ0$ρσ0$, which would be in complete disagreement with observations. This result provides very strong additional support for the conjecture that no natural frustration mechanism, which could lead to a significant contribution of domain walls to the dark energy budget, exists.Keywords2010PhLB..689..145SPhysics Letters BVolume 689, Page 145May 2010>> ADS>> DOI

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