We reinvestigate the thermodynamics of black objects (holes and strings) in
four-dimensional braneworld models that are originally constructed by Emparan,
Horowitz and Myers based on the anti-de Sitter (AdS) C-metric. After proving
the uniqueness of slicing the AdS C-metric, we derive thermodynamic quantities
of the black objects by means of the Euclidean formulation and find that we
have no necessity of requiring any regularization to calculate their classical
action. We show that there exist the Bekenstein-Hawking law and the
thermodynamic first law. The thermodynamic mass of the localized black hole on
a flat brane is negative, and it differs from the one previously derived. We
discuss the thermodynamic stabilities and show that the BTZ black string is
more stable than the localized black holes in a canonical ensemble, except for
an extreme case. We also find a braneworld analogue of the Hawking-Page
transition between the BTZ black string and thermal AdS branes. The localized
black holes on a de Sitter brane is discussed by considering Nariai instanton,
comparing the study of "black cigar" in the five-dimensional braneworld model.Comment: 15 pages, 4 figures, RevTex4, typos fixed, minor correction
