arXiv subjects

Yuichi Sekiwa

Publications and source records attributed to Yuichi Sekiwa.

2 recordsLinked to original sources

arXiv2008

Decay of the cosmological constant by Hawking radiation as quantum tunneling

We calculate the emission rate of Hawking radiation from the cosmological horizon by quantum tunneling approaches. Using the Hamilton-Jacobi and the null geodesic methods, two typical observations are obtained. First, the spectrum of radiation is not strictly pure thermal. Second, the value of the cosmological constant decreases. Our calculation is different from other similar works about Hawking radiation from the cosmological horizon in that the horizon does not shrink but expands by taking into account the back-reaction effect. We show that when a positive frequency particle is materialized near the cosmological horizon, the contribution of a negative frequency partner to the background geometry lowers the value of the cosmological constant. We also touch upon thermodynamics of de Sitter space and the quantum creation of universe.

hep-th↗

arXiv2006

Thermodynamics of de Sitter Black Holes: Thermal Cosmological Constant

We study the thermodynamic properties associated with the black hole event horizon and the cosmological horizon for black hole solutions in asymptotically de Sitter spacetimes. We examine thermodynamics of these horizons on the basis of the conserved charges according to Teitelboim's method. In particular, we have succeeded in deriving the generalized Smarr formula among thermodynamical quantities in a simple and natural way. We then show that cosmological constant must decrease when one takes into account the quantum effect. These observations have been obtained if and only if cosmological constant plays the role of a thermodynamical state variable. We also touch upon the relation between inflation of our universe and a phase transition of black holes.

hep-th↗