The Price of Egalitarianism

We compute the welfare cost of egalitarianism - a tax policy that equalizes wages for all. The benchmark "laissez-faire" economy has features a la Aiyagari (1994) with endogenous labor supply. A progressive income tax provides insurance against income risks but at the cost of efficiency: it undermines highly productive workers' incentives to work. We find that in an economy with the labor-supply elasticity of 1, the welfare cost of egalitarianism, measured in consumption-equivalence units, is only 1% as the welfare gain from insurance against income risks nearly offsets the efficiency loss from distorting labor effort. However, with an elastic labor supply, the welfare cost of egalitarianism is as large as 7.5% of steady state consumption.Egalitarianism; Welfare Cost; Equal-Wage Policy; Income Risks.

Quantum phase transition in a three-level atom-molecule system

We adopt a three-level bosonic model to investigate the quantum phase transition in an ultracold atom-molecule conversion system which includes one atomic mode and two molecular modes. Through thoroughly exploring the properties of energy level structure, fidelity, and adiabatical geometric phase, we confirm that the system exists a second-order phase transition from an atommolecule mixture phase to a pure molecule phase. We give the explicit expression of the critical point and obtain two scaling laws to characterize this transition. In particular we find that both the critical exponents and the behaviors of ground-state geometric phase change obviously in contrast to a similar two-level model. Our analytical calculations show that the ground-state geometric phase jumps from zero to ?pi/3 at the critical point. This discontinuous behavior has been checked by numerical simulations and it can be used to identify the phase transition in the system.Comment: 8 pages,8 figure

Can a Representative-Agent Model Represent a Heterogeneous-Agent Economy?

Accounting for observed fluctuations in aggregate employment, consumption, and real wage using the optimality conditions of a representative household often requires preferences that are incompatible with economic priors (e.g., Mankiw, Rotemberg, and Summers 1985). This discrepancy between the equilibrium model and the aggregate data is often viewed as evidence of the failure of labor-market clearing. We argue that such a conclusion is premature. We construct a model economy where all prices are flexible and all markets clear at all times but household decisions are not readily aggregated because of incomplete capital markets and the indivisible nature of the labor supply. We demonstrate that if we were to explain the model-generated aggregate time series using decisions of a fictitious" stand-in household, such a household is likely to have a non-concave or unstable utility. Our analysis suggests that the representative-agent model often fails to represent an equilibrium outcome of a heterogeneous-agent economy.Representative-agent model, Aggregation, Heterogeneity, Incomplete Markets, Indivisible Labor, GMM Estimation

Comparative Advantage in Cyclical Unemployment

We introduce worker differences in labor supply, reflecting differences in skills and assets, into a model of separations, matching, and unemployment over the business cycle. Separating from employment when unemployment duration is long is particularly costly for workers with high labor supply. This provides a rich set of testable predictions across workers: those with higher labor supply, say due to lower assets, should display more procyclical wages and less countercyclical separations. Consequently, the model predicts that the pool of unemployed will sort toward workers with lower labor supply in a downturn. Because these workers generate lower rents to employers, this discourages vacancy creation and exacerbates the cyclicality of unemployment and unemployment durations. We examine wage cyclicality and employment separations over the past twenty years for workers in the Survey of Income and Program Participation (SIPP). Wages are much more procyclical for workers who work more. This pattern is mirrored in separations; separations from employment are much less cyclical for those who work more. We do see for recessions a strong compositional shift among those unemployed toward workers who typically work less.