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In this paper, we consider the propagation of scalar particles in a higher-dimensional Schwarzschild-de Sitter black-hole spacetime, both on the brane and in the bulk. Our analysis applies for arbitrary partial modes and for both minimal and nonminimal coupling of the scalar field. A general expression for the greybody factor is analytically derived in each case, and its low-energy behavior is studied in detail. Its profile in terms of scalar properties (angular-momentum number and nonminimal coupling parameter) and spacetime properties (number of extra dimensions and cosmological constant) is thoroughly investigated. In contrast to previous studies, the effect of the cosmological constant is taken into account both close to and far away from the black-hole horizon. The dual role of the cosmological constant, that may act either as a helping agent to the emission of scalar particles or as a deterring effect depending on the value of the nonminimal coupling parameter, is also demonstrated. [ABSTRACT FROM AUTHOR]

It is shown that the gray-body factor for a one-dimensional elongated Bose-Einstein condensate (BEC) acoustic black hole with one horizon does not vanish in the low-frequency (ω → 0) limit. This implies that the analog Hawking radiation is dominated by the emission of an infinite number (1/ω) of soft phonons in contrast with the case of a Schwarzschild black hole where the gray-body factor vanishes as ω → 0 and the spectrum is not dominated by low-energy particles. The infrared behaviors of certain correlation functions are also discussed. [ABSTRACT FROM AUTHOR]