Spin-0 and spin-1/2 particles in a constant scalar-curvature background

We study the Klein-Gordon and Dirac equations in the presence of a background metric ds(2) = -dt(2) + dx(2) + e(-2gx) (dy(2) + dz(2)) in a semi-infinite lab (x > 0). This metric has a constant scalar-curvature R = 6g(2) and is produced by a perfect fluid with equation of state p = -rho/3. The eigenfunctions of spin-0 and spin-1/2 particles are obtained exactly, and the quantized energy eigenvalues are compared. It is shown that both of these particles must have nonzero transverse momentum in this background. We show that there is a minimum energy E-min(2) = m(2)c(4) + g(2)c(2)h(2) for bosons (E-KG > E-min), while the fermions have no specific ground state (E-Dirac > mc(2)). (C) 2003 Elsevier Inc. All rights reserved.