Essential spectrum of a fermionic quantum field model

An interaction system of a fermionic quantum field is considered. The state space is defined by a tensor product space of a fermion Fock space and a Hilbert space. It is assumed that the total Hamiltonian is a self-adjoint operator on the state space and bounded from below. Then it is proven that a subset of real numbers is the essential spectrum of the total Hamiltonian. It is applied to the system of a Dirac field coupled to a Klein-Gordon field. Then the HVZ theorem for the system is obtained

On the Effects of Emission Standards as Technical Barriers to Trade: A Foreign Duopoly Case

Employing an environmentally differentiated duopoly model, we analyze how emission standards affect imports, the environment, and social welfare. We show that a strict emission standard is not necessarily import-restrictive, whereas it may possibly degrade the environment. Furthermore, we present evidence that the effect of emission standards on net social surplus depends on the mode of market competition and the degree of marginal social valuation of environmental damage.emission standards, environmentally differentiated duopoly, green market

On Environmental Subsidy/Tax Policy with Heterogeneous Consumers: An Application of an Environmentally Differentiated Duopoly Model

We apply a model of an environmentally differentiated duopoly to the analysis of environmental policy in the form of a subsidy/tax on consumers based on emission levels of products. More specifically, we consider environmental and welfare effects of subsidizing consumers who purchase environmental-friendly goods such as hybrid vehicles. Focusing on types of market coverage by heterogeneous consumers, we examine the issue in the cases of a Bertrand and a Cournot duopoly. In the case of full market coverage with a Bertrand duopoly, an environmental subsidy improves the environment and is socially optimal. However, in the case of partial market coverage, irrespective of mode of competition, the optimal policy depends on the magnitude of the marginal social valuation of environmental damage. That is, if the marginal social valuation of environmental damage is sufficiently large (small), an environmental tax (subsidy) is optimal. Furthermore, in the Bertrand duopoly case, the effect of subsidy on the environment is ambiguous, whereas in the Cournot duopoly case, the subsidy degrades the environment.Environmentally differentiated product, Environmental subsidy/tax, Green market, Bertrand and Cournot duopoly

Super strong nuclear force caused by migrating Kbar mesons - Revival of the Heitler-London-Heisenberg scheme in kaonic nuclear clusters

We have studied the structure of K- pp comprehensively by solving this three-body system in a variational method, starting from the Ansatz that the Lambda(1405) resonance (~ Lambda*) is a K-p bound state. The structure of K-pp reveals a molecular feature, namely, the K- in Lambda* as an "atomic center" plays a key role in producing strong covalent bonding with the other proton. We point out that strongly bound Kbar nuclear systems are formed by ``super strong" nuclear force due to migrating real bosonic particles Kbar a la Heitler-London-Heisenberg, whereas the normal nuclear force is caused by mediating virtual pions. We have shown that the elementary process, p + p --> K+ + Lambda* + p, which occurs in a short impact parameter and with a large momentum transfer, leads to unusually large self-trapping of Lambda* by the involved proton, since the Lambda*-p system exists as a compact doorway state propagating to K-pp.Comment: 11 pages, 5 figure