Poisson equations, higher derivative automorphic forms and string parameter limits

This paper considers the higher derivative terms in the effective action of type II string theory and in particular the behaviour of the automorphic forms they contain in all the different possible limits of the string parameters. The automorphic forms are thought to obey Poisson equations which contain the Laplacian defined on the coset space to which the scalars fields belong and we compute this Laplacian in all the possible string theory limits. We also consider these Poisson equations in the decompactification limit of a single dimension and by making two assumptions, one on the generic form of this equation and the other on the behaviour of the automorphic forms in this limit, we find strong constraints on the allowed form of this differential equation. We show that these constraints allow one to recover much of what was previously known about the automorphic forms corresponding to terms in the effective action that have fourteen or fewer space-time derivatives in a simple way.Comment: 47 pages, references added and typos correcte

Multivariate Discrete First Order Stochastic Dominance

This paper characterizes the principle of first order stochastic dominance in a multivariate discrete setting. We show that a distribution f first order stochastic dominates distribution g if and only if f can be obtained from g by iteratively shifting density from one outcome to another that is better. For the bivariate case, we develop the theoretical basis for an algorithmic dominance test that is easy to implement.multidimensional first degree distributional dominance; robust poverty gap dominance; majorization; generalized equivalence result

More than a decade on, there are still unanswered questionsabout Abu Ghraib and the war on terror

We are now more than a decade on from the release of the Abu Ghraib abuse photos, which led to one of the largest scandals of the War on Terror. While there have been reports and investigations in the decade since, Peter Finn writes that there are still many unanswered questions. He argues that those higher up in the military chain of command, as well as contractors and their companies, still remain unaccountable. In order to bring closure to the victims and their families, a full and frank investigation into abuse by U.S. forces during the War on Terror is still needed

Home production meets time-to-build

An innovation in this paper is to introduce a time-to-build technology for the production of market capital into a model with home production. The paper’s main finding is that the two anomalies that have plagued all household production models—the positive correlation between business and household investment, and household investment leading business investment over the business cycle—are resolved when time-to-build is added.Production (Economic theory) ; Investments

The 2022 midterms: this year’s elections will be the culmination of a series of complex, multilevel, and interconnected voting and political cycles

One of the generally accepted truisms of US politics is that the party which holds the White House tends to lose seats in midterm elections. This maxim has developed within a dynamic and multilevel election system. With the 2022 midterms just over the horizon, Peter Finn explores if the incumbent Democrats will be able to break with electoral tradition and maintain control of the US House and Senate

What happened?: The narrow parameters of Biden’s Washington are now set, but Trump looms large

With the results of the two run-off elections in Georgia, the framework of Washington during the early stages of Joe Biden’s presidency have been set: with Democrats in charge of the White House, the House of Representatives, and (just about) the Senate. Peter Finn cautions that, though the Democrats may well achieve some significant policy goals, they should also expect discord, with Trumpism continuing to be a factor