Dominance and affiliation as factors in the social organization of same-sex groups of elementary school children

The interactional patterns among first- and second- grade children in same-sex activity groups were analyzed in order to describe the relationships among several aspects of social organization and to examine the centrality of dominance and affiliation in social organization. Videotapes of one group of boys (N = 12) and one group of girls (N = 12) were coded. The results indicated that for both male and female groups, it was possible to specify dominance, leadership initiation, and leadership organization hierarchies. Moreover, there was a highly convergent pattern among multiple indicators of social organization centering on dominance and affiliation. However, the correlation patterns after controlling for social play suggested that the initially similar patterns were accounted for in different ways. Among the girls, the primary element linking the various dimensions was level of social play. Among the boys, there remained a smaller yet interrelated network indicating regularity in rank position for dominance, successful bids, recipient of requests, and number of play partners.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24982/1/0000409.pd

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

Measurement of the inclusive isolated-photon cross section in pp collisions at √s = 13 TeV using 36 fb−1 of ATLAS data

The differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb. The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. [Figure not available: see fulltext.