Electromagnetic form factors of the baryon decuplet with flavor SU(3) symmetry breaking

We investigate the electromagnetic form factors of the baryon decuplet within the framework of the $\mathrm{SU(3)}$ self-consistent chiral quark-soliton model, taking into account the $1/N_c$ rotational corrections and the effects of flavor $\mathrm{SU(3)}$ symmetry breaking. We first examine the valence- and sea-quark contributions to each electromagnetic form factor of the baryon decuplet and then the effects of the flavor SU(3) symmetry breaking. The present results are in good agreement with the recent lattice data. We also compute the charge radii, the magnetic radii, the magnetic dipole moments and the electric quadrupole moments, comparing their results with those from other theoretical works. We also make a chiral extrapolation to compare the present results with the lattice data in a more quantitative manner. The results show in general similar tendency to the lattice results. In particular, the results of the $M1$ and $E2$ form factors are in good agreement with those of lattice QCD.Comment: 29 pages, 15 figures. Comparison with the lattice data was elaborate

Group Reputation and the Dynamics of Statistical Discrimination

Previous literature on statistical discrimination explained stereotypes based on the existence of multiple equilibria, in which principals have different self-confirming beliefs about different social groups (Arrow, 1973; Coate and Loury, 1993). However, the literature has not provided an account of where the principals' prior beliefs come from. Moreover, the static models dominating the literature do not offer relevant information about the dynamic paths that lead to each equilibrium. This paper develops a dynamic version of statistical discrimination in which economic players' forward-looking behaviors determine the dynamic paths to each equilibrium. Defining ``Group Reputation'' as the objective information shared by principals regarding the average characteristics of agents belonging to each group, this study identifies groups as advantaged or disadvantaged, based on their initial reputation states, and provides conditions by which a group can switch from one reputation state to another. By understanding this dynamic structure of reputation evolution, we examine the strategy that well-coordinated principals may voluntarily utilize to maximize their profits, helping the group in the reputation trap to improve its skill investment rate.Statistical Discrimination; Group Reputation; Reputation Trap; Forward-Looking Behavior

Emil Brunner's Conception of Missionary Theology: An Analysis and a Critical Appraisal of Its Language Based on His Writings

The aim of this thesis is to undertake an analysis of the expression and the concept of 'missionary theology' based on the writings of Emil Brunner. Through its analysis there are two main objectives: the first is an understanding of Brunner's missionary theology. The second objective is a critical evaluation of it

Lifetime Network Externality and the Dynamics of Group Inequality

The quality of one's social network significantly affects his economic success. Even after the skill acquisition period, the social network influences economic success through various routes such as mentoring, job searching, business connections, or information channeling. In this paper I propose that a social network externality which extends beyond the education period -- what I call a Lifetime Network Externality -- is important in explaining the evolution of between-group inequality in an economy. When the members of a group believe that the quality of their social network will be better in the future, more young group members invest in skill achievement because they expect higher returns on investment realized over the working period. As this is repeated in the following generations, the quality of the group's network improves over time. Combining the Lifetime Network Externality, which operates during the labor market phase of a worker's career, with the traditional concepts of peer and parental effects, which operate during the educational phase (Loury 1977), I suggest a full dynamic picture of group inequality in an economy with multiple social groups. I define a notion of Network Trap, wherein a disadvantaged group cannot improve the quality of its network without a governmental intervention, and I explore the egalitarian policies to mobilize the group out of this trap. This social capital approach suggests a positive effect of equality on economic growth in later stages of economic development and a positive effect of inequality in the early stage of economic development, consistent with Galor and Zeira (1993). Unlike the previous literature, the conclusion is derived without imposing the standard assumption of credit market imperfections. Therefore, this implies that equality, by helping disadvantaged groups to move out of the network trap, has a positive effect on economic development even in a matured economy without binding credit constraints, or in a society with public provision of schooling.Lifetime Network Externality; Group Inequality; Network Trap; Social Capital; Economic Development

Early-type Host Galaxies of Type Ia Supernovae. I. Evidence for Downsizing

Type Ia supernova (SN Ia) cosmology provides the most direct evidence for the presence of dark energy. This result is based on the assumption that the look-back time evolution of SN Ia luminosity, after light-curve corrections, would be negligible. Recent studies show, however, that the Hubble residual (HR) of SN Ia is correlated with the mass and morphology of host galaxies, implying the possible dependence of SN Ia luminosity on host galaxy properties. In order to investigate this more directly, we have initiated spectroscopic survey for the early-type host galaxies, for which population age and metallicity can be more reliably determined from the absorption lines. As the first paper of the series, here we present the results from high signal-to-noise ratio (>100 per pixel) spectra for 27 nearby host galaxies in the southern hemisphere. For the first time in host galaxy studies, we find a significant (~3.9sigma) correlation between host galaxy mass (velocity dispersion) and population age, which is consistent with the "downsizing" trend among non-host early-type galaxies. This result is rather insensitive to the choice of population synthesis models. Since we find no correlation with metallicity, our result suggests that stellar population age is mainly responsible for the relation between host mass and HR. If confirmed, this would imply that the luminosity evolution plays a major role in the systematic uncertainties of SN Ia cosmology.Comment: Accepted for publication in ApJ

Phenomenological Implications of the Topflavor Model

We explore phenomenologies of the topflavour model for the LEP experiment at $m_{_Z}$ scale and the atomic parity violation (APV) experiment in the $C_s$ atoms at low energies. Implications of the model on the $Z$ peak data are studied in terms of the precision variables $\epsilon_i$'s. We find that the LEP data give more stringent constraints on the model parameters than the APV data.Comment: 23 pages (including 5 .eps figs), ReVTeX, the 1st revised version, to appear in Phys. Lett.