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We consider, in an abstract form, a system of “quantum particles” coupled to a Bose field. It is shown that, under suitable hypotheses, the composed system can have a ground state even if the uncoupled particle system has no ground state.
We report that music therapy is effective in the treatment of Alzheimer's disease. We found that the secretion of 17β-estradiol and testosterone, hormones that are supposed to have preventive effects on Alzheimer's disease, is significantly increased by music therapy. During the sessions, patients with Alzheimer's disease were allowed to listen to music and… (More)
We consider a model of quantum particles coupled to a massless quantum scalar eld, called the massless Nelson model, in a non-Fock representation of the time-zero elds which satisfy the canonical commutation relations. We show that the model has a ground state for all values of the coupling constant even in the case where no infrared cutoo is made. The… (More)
We present new classes of time operators of a Hamiltonian H (a self-adjoint operator) with discrete eigenvalues which may be degenerate. Moreover we formulate necessary and sufficient conditions for H to have time operators, determining the general form of them. As corollaries, non-existence theorems of time operators for some classes of H are derived.… (More)
N. UCHIKAWA Shimizu Works, Hitachi, Ltd. Shimizu, Shizuvka, JAPAN A series of scroll compressors for air conditioners with revolutionary high efficiency have been developed and put into commertial production. This development was accomplished through the development of a controlled thrust force mechanism to support the orbiting scroll in the axial direction… (More)
Regularities and higher order regularities of ground states of quantum field models are investigated through the fact that asymptotic annihilation operators vanish ground states. Moreover a sufficient condition for the absence of a ground state is given.
Author(s) Arai, Asao; Hirokawa, Masao Citation Reviews in Mathematical Physics, 13(4): 513-528 Issue Date 2001-04 Doc URL http://hdl.handle.net/2115/38266 Right Electronic version of an article published as Reviews in Mathematical Physics, Vol. 13, Issue 4, 2001, pp. 513-528, DOI: 10.1142/S0129055X01000740 © World Scientific Publishing Company,… (More)
We consider a model of quantum particles coupled to a massless quantum scalar field, called the massless Nelson model, in a non-Fock representation of the timezero fields which satisfy the canonical commutation relations. We show that the model has a ground state for all values of the coupling constant even in the case where no infrared cutoff is made. The… (More)
Let H be a self-adjoint operator on a complex Hilbert space H. A symmetric operator T on H is called a time operator of H if, for all t ∈ R, e−itHD(T ) ⊂ D(T ) (D(T ) denotes the domain of T ) and Te−itHψ = e−itH(T +t)ψ, ∀t ∈ R,∀ψ ∈ D(T ). In this paper, spectral properties of T are investigated. The following results are obtained: (i) If H is bounded… (More)