Quantum analysis for the evolution of the cosmological constant via unitary transformation
JEONG RYEOL CHOI

International Journal of Modern Physics D
16/7
(2007)
The expectation value of the vacuum energy density tied to the cosmological constant is derived from the nonrelativistic quantum deion of the reheating process using the unitary transformation method. Our research is performed for two special cases, i.e. under the assumption of two different duration terms for the radiationdominated era. We suppose that the radiationdominated era lasted for 3,000 years in the first case, and for a very short time so that it can be ignored in the other case. For the former case, the resulting present cosmological constant is much higher than the previously known one. However, for the latter case, it is in good agreement with that obtained from recent cosmic microwave background radiation measurements. Hence, we cannot exclude the possibility that the change of the universe from the radiationdominated era to the matterdominated era might have progressed very swiftly after the beginning of reheating. The analysis shows that the vacuum energy density has been dissipated by the nonconservative force acting on the coherent oscillations of the scalar field according to the expansion of the universe.
 초록
The expectation value of the vacuum energy density tied to the cosmological constant is derived from the nonrelativistic quantum deion of the reheating process using the unitary transformation method. Our research is performed for two special cases, i.e. under the assumption of two different duration terms for the radiationdominated era. We suppose that the radiationdominated era lasted for 3,000 years in the first case, and for a very short time so that it can be ignored in the other case. For the former case, the resulting present cosmological constant is much higher than the previously known one. However, for the latter case, it is in good agreement with that obtained from recent cosmic microwave background radiation measurements. Hence, we cannot exclude the possibility that the change of the universe from the radiationdominated era to the matterdominated era might have progressed very swiftly after the beginning of reheating. The analysis shows that the vacuum energy density has been dissipated by the nonconservative force acting on the coherent oscillations of the scalar field according to the expansion of the universe._{}^{}
 초록
The expectation value of the vacuum energy density tied to the cosmological constant is derived from the nonrelativistic quantum deion of the reheating process using the unitary transformation method. Our research is performed for two special cases, i.e. under the assumption of two different duration terms for the radiationdominated era. We suppose that the radiationdominated era lasted for 3,000 years in the first case, and for a very short time so that it can be ignored in the other case. For the former case, the resulting present cosmological constant is much higher than the previously known one. However, for the latter case, it is in good agreement with that obtained from recent cosmic microwave background radiation measurements. Hence, we cannot exclude the possibility that the change of the universe from the radiationdominated era to the matterdominated era might have progressed very swiftly after the beginning of reheating. The analysis shows that the vacuum energy density has been dissipated by the nonconservative force acting on the coherent oscillations of the scalar field according to the expansion of the universe._{}^{}
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