Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Determinants of Minority-White Differentials in Child Poverty

This paper uses data from the 1993-2001 March Current Population Survey to estimate the extent to which child living arrangements, parental work patterns, and immigration attributes shape racial and ethnic variation in child poverty. Results from multivariate analyses and a standardization technique reveal that parental work patterns as well as child living arrangements are especially consequential for black and Puerto-Rican economic circumstances. Child immigration generation and parental length of residence seem to play a detrimental role in shaping poverty among Asian, Mexican, and Central/South American children. We also found that the extent to which differences in the composition of and returns to parental resources determine white-minority economic gaps varies substantially across racial and ethnic lines. The social and economic implications of the findings for understanding racial and ethnic inequality are discussed in the final section of the article