Report from Working Group 3: Beyond the standard model physics at the HL-LHC and HE-LHC

This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as $3$ ab$^{-1}$ of data taken at a centre-of-mass energy of 14 TeV, and of a possible future upgrade, the High Energy (HE) LHC, defined as $15$ ab$^{-1}$ of data at a centre-of-mass energy of 27 TeV. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by $20-50\%$ on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will, generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Measurement of Higgs couplings to top quarks and τ\tau leptons with the ATLAS detector

Since the discovery of the Higgs boson in 2012 during the first run of the Large Hadron Collider (LHC) at CERN, extensive measurements have been performed to characterize its properties. Its mass, spin, parity and couplings have been studied in detail with no significant deviations from the SM predictions observed. The second run of the LHC saw incredible progress with the addition of new measurements. This thesis highlights the measurements of Higgs couplings to third generation fermions, first with the observation of the $t\bar t H$ process and then through improved $pp \rightarrow H \rightarrow \tau\tau$ cross section measurements. The search for the $t\bar t H$ process is discussed in the context of the $t\bar t H\rightarrow \text{multilepton}$ analysis, with an emphasis on final states with $\tau_\text{had-vis}$. A $t\bar t H$ cross section measurement, obtained in combination with results from $t\bar t (H \rightarrow \gamma \gamma)$, $t\bar t (H \rightarrow ZZ^* \rightarrow 4\ell)$ and $t\bar t (H \rightarrow b\bar{b})$, is also presented. All results are found to be compatible with the Standard Model predictions. The study of Higgs decays involving $\tau$ leptons is expanded upon with the measurement of the $pp \rightarrow H \rightarrow \tau\tau$ cross section using the full Run 2 dataset, and a new method to estimate the largest background to this measurement is introduced. The improvement in the precision of $pp \rightarrow H \rightarrow \tau\tau$ measurements coupled with an increased sensitivity to broader regions of phase space allows for a deeper scrutiny of the Standard Model predictions, with the theory still providing an accurate description of the experimental results

Study of the Associated Production of ttˉt\bar{t} and Higgs with the ATLAS Detector

The observation of the production cross-section of a top-antitop pair in association with the Higgs boson ($t\bar{t}H$) with the ATLAS detector is one of the highest priorities in the physics plan at 13 TeV energies. MultiVariate Analysis techniques are planned to be implemented in the $t\bar{t}H$ multi-lepton channel during Run 2 data analysis as an improvement to the "cut and count" method used in Run 1. In this work, the Boosted Decision Trees and Neural Network algorithms are tested in $t\bar{t}H$ final states with two leptons with same sign electric charge and adjusted in order to obtain better sensitivity and higher separation power between signal and background compared to the counting experiment from Run 1

Lepton Yukawa interactions results by ATLAS and CMS

Slides for Lepton Yukawa Interactions talk at Higgs2021 with results from ATLAS and CMS. Covers $H\rightarrow \tau\tau$ measurements, searches for $H\rightarrow\mu\mu$ and LFV searches in $H\rightarrow e\mu, e\tau, \mu\tau$

Measurement of Higgs couplings to top quarks and τ leptons with the ATLAS detector

Since the discovery of the Higgs boson in 2012 during the first run of the Large Hadron Collider (LHC) at CERN, extensive measurements have been performed to characterize its properties. Its mass, spin, parity and couplings have been studied in detail with no significant deviations from the SM predictions observed. The second run of the LHC saw incredible progress with the addition of new measurements. This thesis highlights the measurements of Higgs couplings to third generation fermions, first with the observation of the ttH process and then through improved pp → H → ττ cross section measurements. The search for the ttH process is discussed in the context of the ttH → multilepton analysis, with an emphasis on final states with τhad-vis. A ttH cross section measurement, obtained in combination with results from tt(H → γγ), tt(H → ZZ* → 4ℓ) and tt(H → bb), is also presented. All results are found to be compatible with the Standard Model predictions. The study of Higgs decays involving τ leptons is expanded upon with the measurement of the pp → H → ττ cross section using the full Run 2 dataset, and a new method to estimate the largest background to this measurement is introduced. The improvement in the precision of pp → H → ττ measurements coupled with an increased sensitivity to broader regions of phase space allows for a deeper scrutiny of the Standard Model predictions, with the theory still providing an accurate description of the experimental results.Ph.D