The Resurgence of the Cusp Anomalous Dimension

This work addresses the resurgent properties of the cusp anomalous dimension's strong coupling expansion, obtained from the integral Beisert-Eden-Staudacher (BES) equation. This expansion is factorially divergent, and its first nonperturbative corrections are related to the mass gap of the $O(6)$ $\sigma$-model. The factorial divergence can also be analysed from a resurgence perspective. Building on the work of Basso and Korchemsky, a transseries ansatz for the cusp anomalous dimension is proposed and the corresponding expected large-order behaviour studied. One finds non-perturbative phenomena in both the positive and negative real coupling directions, which need to be included to address the analyticity conditions coming from the BES equation. After checking the resurgence structure of the proposed transseries, it is shown that it naturally leads to an unambiguous resummation procedure, furthermore allowing for a strong/weak coupling interpolation.Comment: 12 pages, 5 figure

Digital equalization of time-delay array receivers on coherent laser communications

© [2017 Optical Society of America.]. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.Field conjugation arrays use adaptive combining techniques on multi-aperture receivers to improve the performance of coherent laser communication links by mitigating the consequences of atmospheric turbulence on the down-converted coherent power. However, this motivates the use of complex receivers as optical signals collected by different apertures need to be adaptively processed, co-phased, and scaled before they are combined. Here, we show that multiple apertures, coupled with optical delay lines, combine retarded versions of a signal at a single coherent receiver, which uses digital equalization to obtain diversity gain against atmospheric fading. We found in our analysis that, instead of field conjugation arrays, digital equalization of time-delay multi-aperture receivers is a simpler and more versatile approach to accomplish reduction of atmospheric fading.Peer ReviewedPostprint (author's final draft

The Lawrence-Sullivan construction is the right model of I+I^+

We prove that the universal enveloping algebra of the Lawrence-Sullivan construction is a particular perturbation of the complete Baues-Lemaire cylinder of $S^0$. Together with other evidences we present, this exhibits the Lawrence-Sullivan construction as the right model of $I^+$. From this, we also deduce a generalized Euler formula on Bernoulli numbers.Comment: 13 page

Massless L\"uscher Terms and the Limitations of the AdS3 Asymptotic Bethe Ansatz

In AdS5/CFT4 integrability the Bethe ansatz gives the spectrum of long strings, accurate up to exponentially small corrections. This is no longer true in AdS3, as we demonstrate here by studying Luscher F-terms with a massless particle running in the loop. We apply this to the classic test of Hernandez & Lopez, in which the su(2) sector Bethe equations (including one-loop dressing phase) should match the semiclassical string theory result for a circular spinning string. These calculations did not agree in AdS3xS3xT4, and we show that the sum of all massless Luscher F-terms can reproduce the difference.Comment: 15 pages, 1 figure; v2:references, typos and clarification

A Glimpse at the School Dropout Problem

Dropout is a problem for many reasons. One, at the aggregate economy level wherein education is known to be an important determinant of economic growth, premature dropout means loss of potential productivity. And two, within the education sector, dropout raises the cost of achieving a targeted proportion of the population having some level of schooling. The other area where dropout is a problem--and perhaps the more important one--is from the equity perspective. Dropouts may appear small in number but they are preponderant among the poor which thereupon turns the wheels of intergenerational transmission of poverty against them. At the personal level, dropping out of school will mean consigning one to a future of low-income trajectory. Given a choice, one will obviously not opt for this.Philippines, school children, child poverty, school dropout

Population and the Fight Against Poverty

Is poverty incidence higher among families with a bigger family size? Is there a cause and effect in the relationship between family size and poverty incidence? Dr. Aniceto Orbeta Jr. believes that indeed, there is. In this Policy Notes, he provides explanations and evidences of three channels--growth, distribution and conversion--through which demographic changes affect poverty outcomes.poverty, population, demographic changes

The More the Poorer: Why Large Family Size Causes Poverty

What makes a large family more prone to poverty? Why is the poverty incidence invariably higher among households with larger family sizes? This Notes examines three mechanisms that provide answers to these questions, namely, (a) impact of the number of children on the labor force participation and incomes of parents; (b)education of children; and (c) household savings. Read more...poverty, education, Philippines, family size, labor force participation, earnings, household savings