2009/03/31 by Mark Hindmarsh, Huiquan Li
Physics and Astronomy · #Black Holes and Theoretical Physics #Condensation #Eikonal equation #Field (mathematics) #Gravitational singularity #Maxima and minima #Nonlinear Photonic Systems #Perturbation (astronomy) #Quantum Electrodynamics and Casimir Effect #Tachyon #Tachyon condensation #hep-th
paper · pdf · doi:10.1088/1126-6708/2009/06/050
published as JHEP 0906:050,2009 · 4 figures,19pp
arxiv created 2009/05/15 · openalex publication_date 2009/06/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the spacetime-dependent condensation of the tachyon in effective field theories. Previous work identified singularities in the field which appear in finite time: infinite gradients at the kinks, and (in the eikonal approximation) caustics near local minima. By performing a perturbation analysis, and with numerical simulations, we demonstrate and explain key features of the condensation process: perturbations generically freeze, and minima develop singular second derivatives in finite time (caustics). This last has previously been understood in terms of the eikonal approximation to the dynamics. We show explicitly from the field equations how this approximation emerges, and how the caustics develop, both in the DBI and BSFT effective actions. We also investigate the equation of state parameter of tachyon matter showing that it is small, but generically non-zero. The energy density tends to infinity near field minima with a charateristic profile. A proposal to regulate infinities by modifying the effective action is also studied. We find that although the infinities at the kinks are successfully regularised in the time-dependent case, caustics still present.