Greybody factors for a nonminimally coupled scalar field in BTZ black hole background

Abstract

In the present work we study the propagation of a probe nonminimally coupled\nscalar field in BTZ black hole background. We find analytical expressions for\nthe reflection coefficient, the absorption cross-section, and the decay rate in\nthe strong coupling case, where the nonminimal coupling is larger than its\nconformal value $\\xi_{c}= 1/6$. Our main results are summarized in several\nfigures, in which we show how the behavior of the aforementioned quantities\ndepends on the parameters of the theory. Our findings show that i) the\nreflection coefficient tends to zero only for a nonminimal coupling $\\xi \\geq\n0.25$, and ii) in the zero angular-momentum case the greybody factor in the low\nenergy regime tends to a finite constant that generically does not coincide\nwith the area of the horizon of the black hole. There is, however, a special\ncase in which this holds.\n