804 citations · 3.3k across the 158 of their papers we have counts for
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New variational perturbation theory based on deformed oscillator
Hyeong-Chan Kim, Jae Hyung Yee, Sang Pyo Kim
A new variational perturbation theory is developed based on the deformed oscillator. It is shown that the new variational perturbation method provides 200 or 10 times better ac…
Constraint on the Squeeze Parameter of Inflaton from Cosmological Constant
Sang Pyo Kim, Seoktae Koh
The inflaton is highly likely to settle in a squeezed vacuum state after inflation. The relic inflaton after inflation and reheating undergoes a damped oscillatory motion and contr…
Nonequilibrium Extension of the Landau-Lifshitz-Gilbert Equation for Magnetic Systems
Jeongwon Ho, B. C. Choi, F. C. Khanna +1
Using the invariant operator method for an effective Hamiltonian including the radiation-spin interaction, we describe the quantum theory for magnetization dynamics when the spin s…
Quantum Cosmology for Tunneling Universes
Sang Pyo Kim
In a quantum cosmological model consisting of a Euclidean region and a Lorentzian region, Hartle-Hawking's no-bounary wave function, and Linde's wave function and Vilenkin's tunnel…
Magnetic Black Holes Are Also Unstable
Sang Pyo Kim, Don N. Page
Most black holes are known to be unstable to emitting Hawking radiation (in asymptotically flat spacetime). If the black holes are non-extreme, they have positive temperature and e…
Gravitational Wave Spectrum in Inflation with Nonclassical States
Seoktae Koh, Sang Pyo Kim, Doo Jong Song
The initial quantum state during inflation may evolve to a highly squeezed quantum state due to the amplification of the time-dependent parameter, , which may be the…