The Quest for Pionic and Kaonic Nuclear Bound Systems Following Yukawa and Tomonaga

After sketching some historical events related to Yukawa and Tomonaga concerning the birth of mesons, the author describes recent developments in the spectroscopy of pion-nucleus bound states via "pion-transfer" reactions. The role of pions as Nambu-Goldstone bosons in nuclear media is emphasized by recently obtained experimental evidence for the partial restoration of chiral symmetry breaking. New light is shed on Kbar mesons, which play a unique role in forming dense nuclear systems. The basic unit, K- pp, is predicted to possess a molecular structure with quasi-Lambda(1405) as an "atomic constituent". We find here "super strong nuclear force" produced by a migrating real Kbar meson in the Heitler-London-Heisenberg scheme in place of the normal nuclear force mediated by Yukawa's virtual mesons.Comment: 20 pages, 11 figures. Prog. Theor. Phys., in pres

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

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