Spin-Flavor Separation and Non-Fermi Liquid Behavior in the Multichannel Kondo Problem: A Large N Approach

We consider a $SU(N)\times SU(M)$ generalization of the multichannel single-impurity Kondo model which we solve analytically in the limit $N\rightarrow \infty$, $M\rightarrow\infty$, with $\gamma=M/N$ fixed. Non-Fermi liquid behavior of the single electron Green function and of the local spin and flavor susceptibilities occurs in both regimes, $N\le M$ and $N > M$, with leading critical exponents {\em identical} to those found in the conformal field theory solution for {\em all} $N$ and $M$ (with $M\ge 2$). We explain this remarkable agreement and connect it to ``spin-flavor separation", the essential feature of the non-Fermi-liquid fixed point of the multichannel Kondo problem.Comment: 14 pages, 1 Figure (Poscript file attached), Revte

Legal Origins

A central requirement in the design of a legal system is the protection of law enforcers from coercion by litigants through either violence or bribes. The higher the risk of coercion, the greater the need for protection and control of law enforcers by the state. This perspective explains why, in the 12 th and 13 th centuries, the relatively more peaceful England developed trials by jury, while the less peaceful France relied on state-employed judges for both collecting evidence and making decisions. Despite considerable legal evolution, these initial design choices have persisted for centuries (largely because France remained less peaceful than England), and may explain many differences between common and civil law traditions with respect to both the structure of legal systems and the observed social and economic outcomes.

The Curley Effect

James Michael Curley, a four-time mayor of Boston, used wasteful redistribution to his poor Irish constituents and incendiary rhetoric to encourage richer citizens to emigrate from Boston, thereby shaping the electorate in his favor. Boston as a consequence stagnated, but Curley kept winning elections. We present a model of the Curley effect, in which inefficient redistributive policies are sought not by interest groups protecting their rents, but by incumbent politicians trying to shape the electorate through emigration of their opponents or reinforcement of class identities. The model sheds light on ethnic politics in the United States and abroad, as well as on class politics in many countries including Britain.

The Injustice of Inequality

In many countries, the operation of legal, political and regulatory institutions is subverted by the wealthy and the politically powerful for their own benefit. This subversion takes the form of corruption, intimidation, and other forms of influence. We present a model of such institutional subversion focusing specifically on courts and of the effects of inequality in economic and political resources on the magnitude of subversion. We then use the model to analyze the consequences of institutional subversion for the law and order environment in the country, as well as for capital accumulation and growth. We illustrate the model with historical evidence from Gilded Age United States and the transition economies of the 1990s. We also present some cross-country evidence consistent with the basic prediction of the model.

The Curley Effect

James Michael Curley, a four-time mayor of Boston, used wasteful redistribution to his poor Irish constituents and incendiary rhetoric to encourage richer citizens to emigrate from Boston, thereby shaping the electorate in his favor. Boston as a consequence stagnated, but Curley kept winning elections. We present a model of the Curley effect, in which inefficient redistributive policies are sought not by interest groups protecting their rents, but by incumbent politicians trying to shape the electorate through emigration of their opponents or reinforcement of class identities. The model sheds light on ethnic politics in the United States and abroad, as well as on class politics in many countries including Britain.

A Case for Quantity Regulation

Contrary to the standard economic advice, many regulations of financial intermediaries, as well as other regulations such as blue laws, fishing rules, zoning restrictions, or pollution controls, take the form of quantity controls rather than taxes. We argue that costs of enforcement are crucial to understanding these choices. When violations of quantity regulations are cheaper to discover than failures to pay taxes, the former can emerge as the optimal instrument for the government, even when it is less attractive in the absence of enforcement costs. This analysis is especially relevant to situations where private enforcement of regulations is crucial.