Observation of the associated production of the Higgs boson with a top quark pair with the ATLAS experiment at the LHC: a study in the boosted regime of the H→bƀ decay channel

For abstract see PD

Jet substructure at the Large Hadron Collider

Jet substructure has emerged to play a central role at the Large Hadron Collider, where it has provided numerous innovative ways to search for new physics and to probe the standard model, particularly in extreme regions of phase space. This review focuses on the development and use of state-of-the-art jet substructure techniques by the ATLAS and CMS experiments

Oral Nutrition as a Form of Pre-Operative Enhancement in Patients Undergoing Surgery for Colorectal Cancer:A Systematic Review

Background: Nutritional status has major impacts on the outcome of surgery, in particular in patients with cancer. The aim of this review was to assess the merit of oral pre-operative nutritional support as a part of prehabilitation in patients undergoing surgery for colorectal cancer. Methods: A systematic literature search and meta-analysis was performed according to the Preferred Reporting of Systematic Reviews and Meta-Analyses (PRISMA) recommendations in order to review all trials investigating the effect of oral pre-operative nutritional support in patients undergoing colorectal surgery. The primary outcome was overall complication rate. Secondary outcomes were incision infection rate, anastomotic leakage rate, and length of hospital stay. Results: Five randomized controlled trials and one controlled trial were included. The studies contained a total of 583 patients with an average age of 63y (range 23-88y), of whom 87% had colorectal cancer. Malnourishment rates ranged from 8%-68%. All investigators provided an oral protein supplement. Overall patient compliance rates ranged from 72%-100%. There was no significant reduction in the overall complication rate in the interventional groups (odds ratio 0.82; 95% confidence interval 0.52-1.25). Conclusion: Current studies are too heterogeneous to conclude that pre-operative oral nutritional support could enhance the condition of patients undergoing colorectal surgery. Patients at risk have a relatively lean body mass deficit (sarcopenia) rather than an absolute malnourished status. Compliance is an important element of prehabilitation. Targeting patients at risk, combining protein supplements with strength training, and defining standardized patient-related outcomes will be essential to obtain satisfactory result

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

Search for boosted ttH(H->bb) with the ATLAS detector

We have conducted a search for the ttH process with the Higgs decaying to a pair of b quarks using 36.1 fb^-1 of data taken with the ATLAS detector. One of the main challenges for this analysis is the combinatorial ambiguity from the many b quark jets in the final state which makes it difficult to reconstruct the Higgs boson. The boosted analysis specifically targets high-pT final states which helps resolve this issue. We select events where the decay products of the Higgs boson and hadronically decaying top quark are produced close together in a large jet. This requirement gives us access to different kinematics and a simplified combinatorial background compared to the resolved analysis. To select events rich in ttH, we apply cuts on the number of small jets and how likely these are to contain b-hadrons. Multivariate techniques are used to discriminate between signal and background events

Boosted hadronic object identification using jet substructure in ATLAS Run-2

The identification of boosted hadronically decaying particles in ATLAS is discussed, focusing on the Run-2 performance results. An introduction to jets and jet substructure is given, after which different boosted object tagging methods are considered. Three topics are covered: Top/W tagging, H->bb tagging, and mass-decorrelated taggers

Observation of the associated production of the Higgs boson with a top quark pair with the ATLAS experiment at the LHC: a study in the boosted regime of the H?bb decay channel

For abstract see PD

Oral Nutrition as a Form of Pre-Operative Enhancement in Patients Undergoing Surgery for Colorectal Cancer : A Systematic Review

Background: Nutritional status has major impacts on the outcome of surgery, in particular in patients with cancer. The aim of this review was to assess the merit of oral pre-operative nutritional support as a part of prehabilitation in patients undergoing surgery for colorectal cancer. Methods: A systematic literature search and meta-analysis was performed according to the Preferred Reporting of Systematic Reviews and Meta-Analyses (PRISMA) recommendations in order to review all trials investigating the effect of oral pre-operative nutritional support in patients undergoing colorectal surgery. The primary outcome was overall complication rate. Secondary outcomes were incision infection rate, anastomotic leakage rate, and length of hospital stay. Results: Five randomized controlled trials and one controlled trial were included. The studies contained a total of 583 patients with an average age of 63 y (range 23-88 y), of whom 87% had colorectal cancer. Malnourishment rates ranged from 8%-68%. All investigators provided an oral protein supplement. Overall patient compliance rates ranged from 72%-100%. There was no significant reduction in the overall complication rate in the interventional groups (odds ratio 0.82; 95% confidence interval 0.52 - 1.25). Conclusion: Current studies are too heterogeneous to conclude that pre-operative oral nutritional support could enhance the condition of patients undergoing colorectal surgery. Patients at risk have a relatively lean body mass deficit (sarcopenia) rather than an absolute malnourished status. Compliance is an important element of prehabilitation. Targeting patients at risk, combining protein supplements with strength training, and defining standardized patient-related outcomes will be essential to obtain satisfactory results