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

Dietary Energy Balance Modulates Epithelial-to-Mesenchymal Transition and Tumor Progression in Murine Claudin-Low and Basal-like Mammary Tumor Models

Using novel murine models of claudin-low and basal-like breast cancer, we tested the hypothesis that diet-induced obesity (DIO) and calorie restriction (CR) differentially modulate progression of these aggressive breast cancer subtypes. For model development, we characterized two cell lines, “mesenchymal (M)-Wnt” and “epithelial (E)-Wnt,” derived from MMTV-Wnt-1 transgenic mouse mammary tumors. M-Wnt, relative to E-Wnt, cells were tumor-initiating cell (TIC)-enriched (62% vs 2.4% CD44(high)/CD24(low)), and displayed enhanced aldefluor-positivity, epithelial-to-mesenchymal transition (EMT) marker expression, mammosphere-forming ability, migration, invasion, and tumorigenicity (p<0.001, each parameter). M-Wnt and E-Wnt cells clustered with claudin-low and basal-like breast tumors, respectively, in gene expression profiles, and recapitulated these tumors when orthotopically transplanted into ovariectomized C57BL/6 mice. To assess the effects of energy balance interventions on tumor progression and EMT, mice were administered DIO, control or CR diets for 8 weeks before orthotopic transplantation of M-Wnt or E-Wnt cells (for each cell line, n=20 mice/diet), and continued on their diets for 6 weeks while tumor growth was monitored. Relative to control, DIO enhanced M-Wnt (p=0.01), but not E-Wnt, tumor progression; upregulated EMT- and TIC-associated markers including N-cadherin, fibronectin, TGFβ, SNAIL, FOXC2, and Oct4 (p<0.05, each); and increased intratumoral adipocytes. Conversely, CR suppressed M-Wnt and E-Wnt tumor progression (p<0.02, each) and inhibited EMT and intratumoral adipocyte accumulation. Thus dietary energy balance interventions differentially modulate EMT and progression of claudin-low and basal-like tumors. EMT pathway components may represent targets for breaking the obesity-breast cancer link, particularly for preventing and/or controlling TIC-enriched subtypes such as claudin-low breast cancer

Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13 \sqrt{s}=13\, TeV using the ATLAS detector

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and $t\bar{t}$ system kinematic observables using proton--proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV. The data set corresponds to an integrated luminosity of $36.1$ fb$^{-1}$, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum $p_{\rm T} > 500$ GeV and a second with $p_{\rm T}>350$ GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a $b$-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ values. The cross-section for $t\bar{t}$ production in the fiducial phase-space region is $292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)}$ fb, to be compared to the theoretical prediction of $384 \pm 36$ fb

Measurements of ttˉt\bar{t} differential cross-sections of highly boosted top quarks decaying to all-hadronic final states in pppp collisions at s=13 \sqrt{s}=13\, TeV using the ATLAS detector

Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and $t\bar{t}$ system kinematic observables using proton--proton collisions at a center-of-mass energy of $\sqrt{s} = 13$ TeV. The data set corresponds to an integrated luminosity of $36.1$ fb$^{-1}$, recorded in 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. Events with two large-radius jets in the final state, one with transverse momentum $p_{\rm T} > 500$ GeV and a second with $p_{\rm T}>350$ GeV, are used for the measurement. The top-quark candidates are separated from the multijet background using jet substructure information and association with a $b$-tagged jet. The measured spectra are corrected for detector effects to a particle-level fiducial phase space and a parton-level limited phase space, and are compared to several Monte Carlo simulations by means of calculated $\chi^2$ values. The cross-section for $t\bar{t}$ production in the fiducial phase-space region is $292 \pm 7 \ \rm{(stat)} \pm 76 \rm{(syst)}$ fb, to be compared to the theoretical prediction of $384 \pm 36$ fb