Semiclassical (Quantum Field Theory) and Quantum (String) de Sitter Regimes: New Results

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dc.creatorBouchareb, A.
dc.creatorMedrano, M. Ramon
dc.creatorSanchez, N. G.
dc.date2005-11-28
dc.date.accessioned2026-07-07T10:45:21Z
dc.date.available2026-07-07T10:45:21Z
dc.descriptionWe compute the quantum string entropy S_s(m, H) from the microscopic string density of states rho_s (m,H) of mass m in de Sitter space-time. We find for high m, a {\bf new} phase transition at the critical string temperature T_s= (1/2 pi k_B)L c^2/alpha', higher than the flat space (Hagedorn) temperature t_s. (L = c/H, the Hubble constant H acts at the transition as producing a smaller string constant alpha' and thus, a higher tension). T_s is the precise quantum dual of the semiclassical (QFT Hawking-Gibbons) de Sitter temperature T_sem = hbar c /(2πk_B L). We find a new formula for the full de Sitter entropy S_sem (H), as a function of the usual Bekenstein-Hawking entropy S_sem^(0)(H). For L << l_{Planck}, ie. for low H << c/l_Planck, S_{sem}^{(0)}(H) is the leading term, but for high H near c/l_Planck, a new phase transition operates and the whole entropy S_sem (H) is drastically different from the Bekenstein-Hawking entropy S_sem^(0)(H). We compute the string quantum emission cross section by a black hole in de Sitter (or asymptotically de Sitter) space-time (bhdS). For T_sem ~ bhdS << T_s, (early evaporation stage), it shows the QFT Hawking emission with temperature T_sem ~ bhdS, (semiclassical regime). For T_sem ~ bhdS near T_{s}, it exhibits a phase transition into a string de Sitter state of size L_s = l_s^2/L}, l_s= \sqrt{\hbar alpha'/c), and string de Sitter temperature T_s. Instead of featuring a single pole singularity in the temperature (Carlitz transition), it features a square root branch point (de Vega-Sanchez transition). New bounds on the black hole radius r_g emerge in the bhdS string regime: it can become r_g = L_s/2, or it can reach a more quantum value, r_g = 0.365 l_s.
dc.descriptionNew original material
dc.identifierhttps://arxiv.org/abs/hep-th/0511281
dc.identifierhttp://arxiv.org/abs/hep-th/0511281
dc.identifierInt.J.Mod.Phys.D16:1053-1074,2007
dc.identifierdoi:10.1142/S0218271807010596
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/182885
dc.subjectHigh Energy Physics - Theory
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectHigh Energy Physics - Phenomenology
dc.titleSemiclassical (Quantum Field Theory) and Quantum (String) de Sitter Regimes: New Results
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