Measurements of differential cross-sections in top-quark pair events with a high transverse momentum top quark and limits on beyond the Standard Model contributions to top-quark pair production with the ATLAS detector at √s = 13 TeV

Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than 355 GeV and the other top quark decays into ℓνb are presented using 139 fb−1 of data collected by the ATLAS experiment during proton-proton collisions at the LHC. The fiducial cross-section at s = 13 TeV is measured to be σ = 1.267 ± 0.005 ± 0.053 pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of 4.2%. The cross-section is measured differentially as a function of variables characterising the tt¯ system and additional radiation in the events. The results are compared with various Monte Carlo generators, including comparisons where the generators are reweighted to match a parton-level calculation at next-to-next-to-leading order. The reweighting improves the agreement between data and theory. The measured distribution of the top-quark transverse momentum is used to search for new physics in the context of the effective field theory framework. No significant deviation from the Standard Model is observed and limits are set on the Wilson coefficients of the dimension-six operators OtG and Otq(8), where the limits on the latter are the most stringent to date. [Figure not available: see fulltext.]

The ATLAS inner detector trigger performance in pp collisions at 13 TeV during LHC Run 2

The design and performance of the inner detector trigger for the high level trigger of the ATLAS experiment at the Large Hadron Collider during the 2016-2018 data taking period is discussed. In 2016, 2017, and 2018 the ATLAS detector recorded 35.6 fb(-1), 46.9 fb(-1), and 60.6 fb(-1) respectively of proton-proton collision data at a centre-of-mass energy of 13TeV. In order to deal with the very high interaction multiplicities per bunch crossing expected with the 13TeV collisions the inner detector trigger was redesigned during the long shutdown of the Large Hadron Collider from 2013 until 2015. An overview of these developments is provided and the performance of the tracking in the trigger for the muon, electron, tau and b-jet signatures is discussed. The high performance of the inner detector trigger with these extreme interaction multiplicities demonstrates how the inner detector tracking continues to lie at the heart of the trigger performance and is essential in enabling the ATLAS physics programme

Improved hydrogen photoproduction regulated by carbonylcyanide m-chlorophenylhrazone from marine green alga Platymonas subcordiformis grown in CO2-supplemented air bubble column bioreactor

To develop an integrated process of CO2- fixation and H-2 photoproduction by marine green microalga Platymonas subcordiformis, the impact of algal cells grown in CO2- supplemented air bubble column bioreactor was investigated on H-2 photoproduction regulated by carbonylcyanide m- chlorophenylhrazone. Highest cell growth ( 3.85 9 10(6) cells ml(-1)), starch content ( 0.25 +/- 0.08 mg per 10(6) cells) and hydrogen production ( 50 +/- 3 ml1(-1)) were achieved at 3% CO2- supplemented culture, which are respectively 1.4, 2.1, 1.5- fold of the air-supplemented culture. Improved H-2 production correlated well with the increase in starch accumulation. In this process, the algal cells have been recycled for stable H-2 production of 40 - 50 ml l(-1) over five cycles