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

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

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

Primary primers: after months of downplaying covid-19 before catching it, Trump is still likely facing electoral defeat.

President Donald Trump immediately ceased campaigning following his COVID-19 diagnosis last week. Peter Finn argues that a quick recovery is unlikely to benefit Trump when he returns to the campaign, given his previous dismissive tone towards the pandemic, which included mocking his Democratic opponent, former Vice President Joe Biden, for wearing a mask at last week’s debate

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

The 2020 Democratic Convention showed unusual unity, though ideological divisions remain.

This week the Democratic Party held their online 2020 presidential nominating convention. Peter Finn writes that while history has been made with the nomination of Kamala Harris as Joe Biden’s running mate, the party’s alliance of convenience with Republican never-Trumpers could spell discord for the Democrats in the future

The 2022 midterms: the elections and how to follow them

Even for those who regularly study and write about US elections, they can appear complex and hard to follow. Ahead of the 2022 midterms, which will see elections for 435 US House members, 34 US Senators and hundreds of state and local officials, Peter Finn highlights some useful numbers that can act as shortcuts to navigate the next few months, and provide background for the midterm results as they come in