String Junctions and the BPS Spectrum of N=2 SU(2) Theory with Massive Matters

We study the BPS spectrum of four dimensional N=2 SU(2) theory with massive fundamental matters using the D3-brane probe. Since the BPS states are realized by string webs subject to the BPS conditions, we determine explicitly the configurations of such webs. It is observed that there appear BPS string webs with multiple of junctions corresponding to the fact that the curves of marginal stability in massive theory are infinitely nested. In terms of the string configurations, various properties of the curves of marginal stability are explained intuitively.Comment: 16 pages, LaTex, 5 figure

Coupling Constant Dependence of the Kaluza--Klein Spectrum in Five-Dimensional SQCD on S^1

We investigate the Kaluza--Klein (KK) spectrum of N=1 supersymmetric gauge theory compactified on a circle. We concentrate on a model with gauge group SU(2) and four massless matter fields in the fundamental representation. We derive the exact mass formula of KK modes by using Seiberg--Witten theory. From the mass formula and the D3-brane probe realization, we determine the spectrum of KK modes of matter fields and gauge fields. As a result, we find that the lightest KK state of gauge fields is stable for all the vacuum moduli space, while the lightest KK state of matter fields decays easier than other KK states in a region of the moduli space. The region becomes small as we decrease the five-dimensional gauge coupling constant g_5, and vanishes as we take the limit g_5->0. This result continuously connects the known KK spectrum in the weak coupling limit and that in the strong coupling limit.Comment: 14 pages, 8 figure

Who Supports Redistribution?

Using an original dataset, we investigated the determinants of individual preferences over income redistribution in Japan. Although income level is negatively correlated with support for redistribution, it does not explain much; there are other important factors, which relate to dynamics and uncertainty such as income risk. Even after controlling for income, both risk-averse individuals and those who expect to be unemployed in the future favor greater redistribution. Interaction of aging and mobility proved important. Relatively poor elderly, who presumably have few prospects of upward mobility, strongly support greater redistribution, whereas younger people are less sympathetic to such a policy.

Asking About Changes in Happiness in a Daily Web Survey

This paper investigates whether the level of happiness and integrated process of changes in happiness are the same. Using the daily data of two waves of four and six months each, we found that the level of happiness is stationary, whereas the integrated process of changes is non-stationary with a rising trend, implying that they are different series. An examination of the causes of the difference indicated that although adaptation completely influences the level of happiness, it only partially influences the change in happiness. This may be because the latter is based on a comparison between today and yesterday.