A realization of certain modules for the N=4N=4 superconformal algebra and the affine Lie algebra A2(1)A_2 ^{(1)}

We shall first present an explicit realization of the simple $N=4$ superconformal vertex algebra $L_{c} ^{N=4}$ with central charge $c=-9$. This vertex superalgebra is realized inside of the $b c \beta \gamma$ system and contains a subalgebra isomorphic to the simple affine vertex algebra $L_{A_1} (- \tfrac{3}{2} \Lambda_0)$. Then we construct a functor from the category of $L_{c} ^{N=4}$--modules with $c=-9$ to the category of modules for the admissible affine vertex algebra $L_{A_{2} } (-\tfrac{3}{2} \Lambda_0)$. By using this construction we construct a family of weight and logarithmic modules for $L_{c} ^{N=4}$ and $L_{A_{2} } (-\tfrac{3}{2} \Lambda_0)$. We also show that a coset subalgebra of $L_{A_{2} } (-\tfrac{3}{2} \Lambda_0)$ is an logarithmic extension of the $W(2,3)$--algebra with $c=-10$. We discuss some generalizations of our construction based on the extension of affine vertex algebra $L_{A_1} (k \Lambda_0)$ such that $k+2 = 1/p$ and $p$ is a positive integer.Comment: 27 page

Political Contagion in Currency Crises

Existing models of contagious currency crises are summarized and surveyed, and it is argued that more weight should be put on political factors. Towards this end, the concept of political contagion introduced, whereby contagion in speculative attacks across currencies arises solely because of political objectives of countries. A specific model of membership' contagion is presented. The desire to be part of a political-economic union, where maintaining a fixed exchange rate is a condition for membership and where the value of membership depends positively on who else is a member, is shown to give rise to potential contagion. We then present evidence suggesting that political contagion may have been important in the 1992-3 EMS crisis.

Central Bank Independence, Democracy, and Dollarization

Is there a fundamental conflict between insulating monetary policy from popular pressures, seen as essential to sound monetary policy, and making policy responsive to the popular will, seen as fundamental to democracy? We argue that strongly independent monetary policy is not inconsistent with democratic control of policymaking, once one realizes that a key feature of democratic policymaking is the decision to remove some decisions from “day-to-day” political pressures. This is the essence of "constitutionalism," central to the functioning of democracy, by which certain decisions are made difficult to reverse. It is further argued that a conflict between popular sovereignty and policymaker independence is not unique to monetary policy, but actually characterizes most policymaking in a democracy, with institutions designed to insulate policymaking from popular pressures. A constitutional perspective implies that extreme forms of commitment, such as a dollarization, are similarly consistent with democracy. One argument for such constraints on monetary policy (as opposed to fiscal policy, for example) is agreement on what good monetary policy means.central bank independence; constitutional democracy; democratic control

Free field realization of the twisted Heisenberg-Virasoro algebra at level zero and its applications

We investigate the free fields realization of the twisted Heisenberg-Virasoro algebra $\mathcal{H}$ at level zero. We completely describe the structure of the associated Fock representations. Using vertex-algebraic methods and screening operators we construct singular vectors in certain Verma modules as Schur polynomials. We completely solve the irreducibility problem for tensor product of irreducible highest weight modules with intermediate series. We also determine the fusion rules for an interesting subcategory of $\mathcal{H}$-modules. Finally, as an application we present a free field realization of the $W(2,2)$-algebra and interpret the $W(2,2)$-singular vectors as $\mathcal{H}$-singular vectors in Verma modules.Comment: To appear in Journal of Pure and Applied Algebra, 24 page