Three-loop octagons and n-gons in maximally supersymmetric Yang-Mills theory

We study the S-matrix of planar $\mathcal{N}=4$ supersymmetric Yang-Mills theory when external momenta are restricted to a two-dimensional subspace of Minkowski space. We find significant simplifications and new, interesting structures for tree and loop amplitudes in two-dimensional kinematics; in particular, the higher-point amplitudes we consider can be obtained from those with lowest-points by a collinear uplifting. Based on a compact formula for one-loop N${}^2$MHV amplitudes, we use an equation proposed previously to compute, for the first time, the complete two-loop NMHV and three-loop MHV octagons, which we conjecture to uplift to give the full $n$-point amplitudes up to simpler logarithmic terms or dilogarithmic terms.Comment: v2: important typos fixed. 38 pages, 4 figures. An ancillary file with two-loop NMHV "remainders" for n=10,12 can be found at http://www.nbi.dk/~schuot/nmhvremainders.zi

Life Satisfaction in Urban China: Components and Determinants

Survey data from urban China in 2002 show levels of life satisfaction to be low, but not exceptionally so, by international comparison. Many of the determinants of life satisfaction in urban China appear comparable to those for people in other countries. These include, inter alia, unemployment, income, marriage, sex, health and age. Communist Party membership and political participation raise life satisfaction. People appear fairly satisfied with economic growth and low inflation, and this contributes to their overall life satisfaction. There is dissatisfaction over pollution, but this – like job insecurity – does not appear to impact on life satisfaction.economic growth, happiness, life satisfaction, unemployment, China

Social Protection and Migration in China: What Can Protect Migrants from Economic Uncertainty?

Job-related welfare entitlements are common in China. Migrants who do not hold urban registration are, in principle, not entitled to job-related welfare even if they are employees in the State sector. The official explanation is that rural-urban migrants are allocated access to farm land in their rural origins, and hence their welfare rights and security are covered by this entitlement to the use of land. In this paper, we look at whether migrants still benefited from these opportunities. Second, we investigate whether it is the poor, the unentitled and the vulnerable that are excluded from public protection programs. Chinese official social protection programs are, like in most western countries, officially designated as being for poverty alleviation. However would such programs still be targeted in ways that limit their coverage, curtail the range of basic needs provided for and allocate benefits very unequally? Thirdly, we explore whether households with favourable productive characteristics are more likely to get into social protection programs. Here, the ongoing debate concerning equality of opportunity and equality of outcomes has some relevance. Finally, we examine the roles social networks or Guanxi (the Chinese term for social connections) may play in dealing with economic shocks.social protection, migration, entitlement, China

Life Satisfaction in Urban China: Components and Determinants

Survey data from urban China in 2002 show levels of life satisfaction to be low, but not exceptionally so, by international comparison. Many of the determinants of life satisfaction in urban China appear comparable to those for people in other countries. These include, inter alia, unemployment, income, marriage, sex, health and age. Communist Party membership and political participation raise life satisfaction. People appear fairly satisfied with economic growth and low inflation, and this contributes to their overall life satisfaction. There is dissatisfaction over pollution, but this – like job insecurity – does not appear to impact on life satisfaction.life satisfaction, happiness, economic growth, unemployment, China

Growing out of poverty: trends and patterns of urban poverty in China 1988–2002

This paper estimates trends in absolute poverty in urban China from 1988 to 2002 using the Chinese Household Income Project (CHIP) surveys. Poverty incidence curves are plotted, showing that poverty has fallen markedly during the period regardless of the exact location of the poverty line. Income inequality rose from 1988 to 1995 but has been fairly constant thereafter. Models of the determination of income and poverty reveal widening differentials by education, sex and party membership. Income from government anti-poverty programs has little impact on poverty, which has fallen almost entirely due to overall economic growth rather than redistribution.poverty, inequality, economic growth, welfare, public policy, China