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Texas A&M University
Mathematics

Mathematical Physics and Harmonic Analysis Seminar

Date: September 10, 2021

Time: 1:50PM - 2:50PM

Location: BLOC 628

Speaker: Agam Shayit, TAMU

  

Title: Vacuum energy density and pressure inside a soft wall

Abstract: In the study of quantum vacuum energy and the Casimir effect, it is desirable to model the conductor by a potential of the form V(z) = z^α. Unlike the standard Dirichlet wall, this model does not violate the principle of virtual work under regularization. Previously, this ``soft wall" model was formalized for a massless scalar field, and the expectation value of the stress tensor was expressed in terms of the reduced Green function of the equation of motion. In the limit of interest α >> 1, which corresponds to the Dirichlet wall, a closed-form expression for the reduced Green function cannot be found. Here we develop a piecewise approximation scheme incorporating the perturbative and WKB expansions of the Green function, as well as an interpolating spline in the region where neither expansion is valid. We then apply the scheme to the sextic soft wall and use it to compute the renormalized energy density and pressure inside the cavity for various conformal parameters. The consistency of the results is verified by comparison to their numerical counterparts and verification of the trace anomaly and the conservation law. Finally, we use the approximation scheme to reproduce the energy density inside the quadratic wall, which was previously calculated exactly.