Study of High-Transverse-Momentum Higgs Boson Production in Association with a Vector Boson in the qqbb Final State with the ATLAS Detector.

This Letter presents the first study of Higgs boson production in association with a vector boson (V=W or Z) in the fully hadronic qqbb final state using data recorded by the ATLAS detector at the LHC in proton-proton collisions at sqrt[s]=13 TeV and corresponding to an integrated luminosity of 137 fb^{-1}. The vector bosons and Higgs bosons are each reconstructed as large-radius jets and tagged using jet substructure techniques. Dedicated tagging algorithms exploiting b-tagging properties are used to identify jets consistent with Higgs bosons decaying into bb[over ¯]. Dominant backgrounds from multijet production are determined directly from the data, and a likelihood fit to the jet mass distribution of Higgs boson candidates is used to extract the number of signal events. The VH production cross section is measured inclusively and differentially in several ranges of Higgs boson transverse momentum: 250-450, 450-650, and greater than 650 GeV. The inclusive signal yield relative to the standard model expectation is observed to be µ=1.4_{-0.9}^{+1.0} and the corresponding cross section is 3.1±1.3(stat)_{-1.4}^{+1.8}(syst) pb.

Measurement of the Centrality Dependence of the Dijet Yield in p+Pb Collisions at sqrt[s_{NN}]=8.16 TeV with the ATLAS Detector.

ATLAS measured the centrality dependence of the dijet yield using 165 nb^{-1} of p+Pb data collected at sqrt[s_{NN}]=8.16 TeV in 2016. The event centrality, which reflects the p+Pb impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, R_{CP}, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The R_{CP} shows a scaling with the Bjorken x of the parton originating from the proton, x_{p}, while no such trend is observed as a function of x_{Pb}. This analysis provides unique input to understanding the role of small proton spatial configurations in p+Pb collisions by covering parton momentum fractions from the valence region down to x_{p}∼10^{-3} and x_{Pb}∼4×10^{-4}.

Search for New Phenomena in Two-Body Invariant Mass Distributions Using Unsupervised Machine Learning for Anomaly Detection at sqrt[s]=13 TeV with the ATLAS Detector.

Searches for new resonances are performed using an unsupervised anomaly-detection technique. Events with at least one electron or muon are selected from 140 fb^{-1} of pp collisions at sqrt[s]=13 TeV recorded by ATLAS at the Large Hadron Collider. The approach involves training an autoencoder on data, and subsequently defining anomalous regions based on the reconstruction loss of the decoder. Studies focus on nine invariant mass spectra that contain pairs of objects consisting of one light jet or b jet and either one lepton (e,µ), photon, or second light jet or b jet in the anomalous regions. No significant deviations from the background hypotheses are observed. Limits on contributions from generic Gaussian signals with various widths of the resonance mass are obtained for nine invariant masses in the anomalous regions.

Observation of WZγ Production in pp Collisions at sqrt[s]=13 TeV with the ATLAS Detector.

This Letter reports the observation of WZγ production and a measurement of its cross section using 140.1±1.2 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The WZγ production cross section, with both the W and Z bosons decaying leptonically, pp→WZγ→ℓ^{'}^{±}νℓ^{+}ℓ^{-}γ (ℓ^{(^{'})}=e, µ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01±0.30(stat)±0.16(syst) fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50±0.06 fb. The observed significance of the WZγ signal is 6.3σ, compared with an expected significance of 5.0σ.

Measurement of Suppression of Large-Radius Jets and Its Dependence on Substructure in Pb+Pb Collisions at sqrt[s_{NN}]=5.02 TeV with the ATLAS Detector.

This letter presents a measurement of the nuclear modification factor of large-radius jets in sqrt[s_{NN}]=5.02 TeV Pb+Pb collisions by the ATLAS experiment. The measurement is performed using 1.72 nb^{-1} and 257 pb^{-1} of Pb+Pb and pp data, respectively. The large-radius jets are reconstructed with the anti-k_{t} algorithm using a radius parameter of R=1.0, by reclustering anti-k_{t} R=0.2 jets, and are measured over the transverse momentum (p_{T}) kinematic range of 158

Observation of Single-Top-Quark Production in Association with a Photon Using the ATLAS Detector.

This Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139 fb^{-1} of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section is measured to be 688±23(stat) _{-71}^{+75}(syst) fb, to be compared with the standard model prediction of 515_{-42}^{+36} fb at next-to-leading order in QCD.

Measurement of the Sensitivity of Two-Particle Correlations in pp Collisions to the Presence of Hard Scatterings.

A key open question in the study of multiparticle production in high-energy pp collisions is the relationship between the "ridge"-i.e., the observed azimuthal correlations between particles in the underlying event that extend over all rapidities-and hard or semihard scattering processes. In particular, it is not known whether jets or their soft fragments are correlated with particles in the underlying event. To address this question, two-particle correlations are measured in pp collisions at sqrt[s]=13 TeV using data collected by the ATLAS experiment at the LHC, with an integrated luminosity of 15.8 pb^{-1}, in two different configurations. In the first case, charged particles associated with jets are excluded from the correlation analysis, while in the second case, correlations are measured between particles within jets and charged particles from the underlying event. Second-order flow coefficients, v_{2}, are presented as a function of event multiplicity and transverse momentum. These measurements show that excluding particles associated with jets does not affect the measured correlations. Moreover, particles associated with jets do not exhibit any significant azimuthal correlations with the underlying event, ruling out hard processes contributing to the ridge.

Observation of the γγ→ττ Process in Pb+Pb Collisions and Constraints on the τ-Lepton Anomalous Magnetic Moment with the ATLAS Detector.

This Letter reports the observation of τ-lepton-pair production in ultraperipheral lead-lead collisions Pb+Pb→Pb(γγ→ττ)Pb and constraints on the τ-lepton anomalous magnetic moment a_{τ}. The dataset corresponds to an integrated luminosity of 1.44 nb^{-1} of LHC Pb+Pb collisions at sqrt[s_{NN}]=5.02 TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a τ-lepton decay, an electron or charged-particle track(s) from the other τ-lepton decay, little additional central-detector activity, and no forward neutrons. The γγ→ττ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations and a signal strength of µ_{ττ}=1.03_{-0.05}^{+0.06} assuming the standard model value for a_{τ}. To measure a_{τ}, a template fit to the muon transverse-momentum distribution from τ-lepton candidates is performed, using a dimuon (γγ→µµ) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for a_{τ} is -0.057

Observation of an Excess of Dicharmonium Events in the Four-Muon Final State with the ATLAS Detector.

A search is made for potential ccc[over ¯]c[over ¯] tetraquarks decaying into a pair of charmonium states in the four muon final state using proton-proton collision data at sqrt[s]=13 TeV, corresponding to an integrated luminosity of 140 fb^{-1} recorded by the ATLAS experiment at LHC. Two decay channels, J/ψ+J/ψ→4µ and J/ψ+ψ(2S)→4µ, are studied. Backgrounds are estimated based on a hybrid approach involving Monte Carlo simulations and data-driven methods. Statistically significant excesses with respect to backgrounds dominated by the single parton scattering are seen in the di-J/ψ channel consistent with a narrow resonance at 6.9 GeV and a broader structure at lower mass. A statistically significant excess is also seen in the J/ψ+ψ(2S) channel. The fitted masses and decay widths of the structures are reported.

Strong Constraints on Jet Quenching in Centrality-Dependent p+Pb Collisions at 5.02 TeV from ATLAS.

Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including pp and p+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb^{-1} of p+Pb and 3.6 pb^{-1} of pp collisions at 5.02 TeV. The yields of charged hadrons with p_{T}^{ch}>0.5 GeV near and opposite in azimuth to jets with p_{T}^{jet}>30 or 60 GeV, and the ratios of these yields between p+Pb and pp collisions, I_{pPb}, are reported. The collision centrality of p+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The I_{pPb} values are consistent with unity within a few percent for hadrons with p_{T}^{ch}>4 GeV at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central p+Pb collisions.

Test of CP Invariance in Higgs Boson Vector-Boson-Fusion Production Using the H→γγ Channel with the ATLAS Detector.

A test of CP invariance in Higgs boson production via vector-boson fusion has been performed in the H→γγ channel using 139 fb^{-1} of proton-proton collision data at sqrt[s]=13 TeV collected by the ATLAS detector at the LHC. The optimal observable method is used to probe the CP structure of interactions between the Higgs boson and electroweak gauge bosons, as described by an effective field theory. No sign of CP violation is observed in the data. Constraints are set on the parameters describing the strength of the CP-odd component in the coupling between the Higgs boson and the electroweak gauge bosons in two effective field theory bases: d[over ˜] in the HISZ basis and c_{HW[over ˜]} in the Warsaw basis. The results presented are the most stringent constraints on CP violation in the coupling between Higgs and weak bosons. The 95% C.L. constraint on d[over ˜] is derived for the first time and the 95% C.L. constraint on c_{HW[over ˜]} has been improved by a factor of 5 compared to the previous measurement.

Rare left colic artery variation of the gut arterial system.

Most variations of the abdominal blood supply are related to branching of the coeliac trunk and superior mesenteric artery. This case details a remarkable variation in the branching pattern of the left colic artery (LCA) observed during routine cadaveric dissection of an 84-year-old male donor. An anomalous common trunk, originating from the common hepatic artery, gave rise to three branches: 1) an accessory posterior pancreaticoduodenal artery to the head of the pancreas and adjacent duodenum, 2) the dorsal pancreatic artery anastomosing with branches of the splenic artery, and 3) the LCA. The LCA descended between the splenic vein and superior mesenteric artery to supply the left colic flexure and form a collateral route with the middle colic artery by contributing to the marginal artery of Drummond. Knowledge of this variation is clinically relevant for surgical and radiological procedures in the abdomen.

Combined Measurement of the Higgs Boson Mass from the H→γγ and H→ZZ

A measurement of the mass of the Higgs boson combining the H→ZZ^{*}→4ℓ and H→γγ decay channels is presented. The result is based on 140 fb^{-1} of proton-proton collision data collected by the ATLAS detector during LHC run 2 at a center-of-mass energy of 13 TeV combined with the run 1 ATLAS mass measurement, performed at center-of-mass energies of 7 and 8 TeV, yielding a Higgs boson mass of 125.11±0.09(stat)±0.06(syst)=125.11±0.11 GeV. This corresponds to a 0.09% precision achieved on this fundamental parameter of the Standard Model of particle physics.

Search for Dark Photons in Rare Z Boson Decays with the ATLAS Detector.

A search for events with a dark photon produced in association with a dark Higgs boson via rare decays of the standard model Z boson is presented, using 139 fb^{-1} of sqrt[s]=13 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider. The dark boson decays into a pair of dark photons, and at least two of the three dark photons must each decay into a pair of electrons or muons, resulting in at least two same-flavor opposite-charge lepton pairs in the final state. The data are found to be consistent with the background prediction, and upper limits are set on the dark photon's coupling to the dark Higgs boson times the kinetic mixing between the standard model photon and the dark photon, α_{D}ϵ^{2}, in the dark photon mass range of [5, 40] GeV except for the ϒ mass window [8.8, 11.1] GeV. This search explores new parameter space not previously excluded by other experiments.

Patient tracking during treatment of children with cancer in India - An exploratory study.

BACKGROUND: Abandonment of treatment, a major cause of treatment failure in low- and middle-income countries like India, is particularly high during the diagnostic and initial phase of treatment. Tracking of patients during this risk period may reduce treatment abandonment rates and increase quality of care. AIM: The primary aim was to pilot the use and check the acceptability of a tool for tracking children with cancer in New Delhi during the initial part of their treatment. Secondary aim was to estimate abandonment rates among these patients. METHODS: This prospective study was carried out in two centers of North India in New Delhi and enrolled children less than 18 years diagnosed with cancer at these centers and who had registered with Cankids for social support. Parent support group (PSG) workers maintained contact with the child's family at least once a week for the first 12 weeks. Details of each contact and subsequent action were recorded in a customized book (called "You are not alone" or YANA Book). Descriptive analysis of these contacts was done in Microsoft Excel and presented in frequencies and percentages. The five-point Likert scale was used to check the acceptability of the tool among the PSG workers. RESULTS: Seven PSG workers enrolled and tracked 81 patients (73% male with a median age of 6 years). During the 12-week study period, 986 contacts were attempted and three (3.7%) patients had abandoned their treatment. All PSG workers strongly agreed that the YANA book was simple to understand and use, decreased their workload, and helped provide better assistance to patients. CONCLUSION: The tool for patient tracking was well accepted by the PSG workers and considered easy to use. We now plan to implement our model as a routine service at all the partnering hospitals in India.

A unique case of extrarenal calyces and associated vascular variations in an adult female cadaver.

The following urogenital and vascular anomalies were observed in the left kidney of an 81-year-old female cadaver during routine dissection: three extrarenal calyces; an accessory renal artery originating directly from the abdominal aorta; and a circumaortic renal vein. The typical renal anatomical structures were identified, from anterior to posterior, as the renal vein, renal artery, and ureter appearing near the hilum of the left kidney. After closer examination, three extrarenal calyces were observed exiting from the hilum of the left kidney to form the pelvis, then narrowed and became the ureter which descended 21.5 cm to empty into the bladder. The accessory renal artery originated from the lateral aspect of the abdominal aorta 7.3 cm below the aortic origin of the left renal artery. A corresponding accessary renal vein, identified as a circumaortic vein, left the hilum 4.5 cm below the left renal vein and travelled posterior to the abdominal aorta to drain into the inferior vena cava. Extrarenal calyces are rare among urogenital tract variations. They can be associated with embryological abnormalities such as renal ectopia, horseshoe kidney or malrotation as well as clinical manifestations such as pelviureteric junction obstruction and hydronephrosis. Compression of the accessory renal artery can cause decreased blood flow to the inferior pole of the left kidney, thereby causing fibrosis, atrophy, or renal failure. The retro-aortic path of the circumaortic renal vein has been associated with posterior nutcracker phenomenon, haematuria, left renal vein thrombus formation, and renal vein hypertension. This unique combination of a collecting system anomaly and extrarenal vessel variations could have significant implications in abdominal surgery.

Tetanus of suspected dental causality.

Tetanus infection by Clostridium tetani is a major health problem in many developing countries, including India. Significant morbidity and mortality is attributed to lack of awareness, hygiene and incomplete vaccination. The most common cause of tetanus infection follows cutaneous injury or infection. However, a localized point of entry cannot always be determined. Tetanus has been associated with tooth extraction, root canal therapy, gross caries, periodontal abscess and intraoral soft tissue trauma. The classic symptoms of trismus and risus sardonicus may result in an initial presentation to an oral and maxillofacial surgeon. Due to the rarity of this infection, the dentist or the health care provider may fail to corroborate the findings and be unsuspecting of the diagnosis. Prompt recognition is the key in such a scenario due to the inherent risk of rapid progress of symptoms, progressive deterioration of the health condition and catastrophic complications. A sound knowledge of the effects of tetanospasmin, the disease process, prevention and vaccination against tetanus with its management is essential for health care workers. The authors hereby present a case of tetanus with a suspected dental etiology to make the dental fraternity aware of this lurking malady.

Building resilient and responsive research collaborations to tackle antimicrobial resistance-Lessons learnt from India, South Africa, and UK.

Research, collaboration, and knowledge exchange are critical to global efforts to tackle antimicrobial resistance (AMR). Different healthcare economies are faced with different challenges in implementing effective strategies to address AMR. Building effective capacity for research to inform AMR-related strategies and policies is recognised as an important contributor to success. Interdisciplinary, intersector, as well as international collaborations are needed to span global to local efforts to tackle AMR. The development of reciprocal, long-term partnerships between collaborators in high-income and in low- and middle-income countries (LMICs) needs to be built on principles of capacity building. Using case studies spanning local and international research collaborations to codesign, implement, and evaluate strategies to tackle AMR, we have evaluated and build upon the ESSENCE criteria for capacity building in LMICs. The first case study describes the local codesign and implementation of antimicrobial stewardship (AMS) in the state of Kerala in India. The second case study describes an international research collaboration investigating AMR surgical patient pathways in India, the UK, and South Africa. We describe the steps undertaken to develop robust, agile, and flexible AMS research and implementation teams. Notably, investing in capacity building ensured that the programmes described in these case studies were sustained through the current severe acute respiratory syndrome coronavirus pandemic. Describing the strategies adopted by a local and an international collaboration to tackle AMR, we provide a model for capacity building in LMICs that can support sustainable and agile AMS programmes.

Epidemiology of tuberculosis among healthcare personnel in New York City.

BACKGROUND: We have updated the epidemiology of tuberculosis (TB) among healthcare personnel (HCP) in New York City (NYC), USA, during a period of declining TB burden.METHODS: Using routinely collected Health Department data for NYC TB cases from 2001 to 2014, we conducted a retrospective descriptive analysis. P values were calculated using Pearson's χ² or Fisher's exact test for categorical data; Wilcoxon rank-sum test was used to compare medians. We used the Cochran-Armitage test for trend and linear regression for trend analyses.RESULTS: HCP accounted for 6% of adults with TB throughout the study period and were more likely than other adults to be female (68% vs. 37%, P ≤ 0.0001), have extrapulmonary-only disease (31% vs. 23%, P ≤ 0.0001), have an isolate with multidrug resistance (4% vs. 2%, P = 0.0211), and report a previous history of latent TB infection (LTBI) (51% vs. 23%, P ≤ 0.0001). Compared to non-US-born HCP, US-born HCP were more likely to have HIV infection (18% vs. 8%, P = 0.0011) or a genotypically clustered isolate (67% vs. 37%, P ≤ 0.0001) and less likely to report history of prior LTBI (43% vs. 54%, P = 0.0128).CONCLUSIONS: Further research is needed to explore transmission and occupational risk among HCP. New approaches are needed to optimize completion of prophylaxis for HCP with LTBI.

Haploinsufficiency of X-linked intellectual disability gene CASK induces post-transcriptional changes in synaptic and cellular metabolic pathways.

Heterozygous mutations in the X-linked gene CASK are associated with intellectual disability, microcephaly, pontocerebellar hypoplasia, optic nerve hypoplasia and partially penetrant seizures in girls. The Cask+/- heterozygous knockout female mouse phenocopies the human disorder and exhibits postnatal microencephaly, cerebellar hypoplasia and optic nerve hypoplasia. It is not known if Cask+/- mice also display seizures, nor is known the molecular mechanism by which CASK haploinsufficiency produces the numerous documented phenotypes. 24-h video electroencephalography demonstrates that despite sporadic seizure activity, the overall electrographic patterns remain unaltered in Cask+/- mice. Additionally, seizure threshold to the commonly used kindling agent, pentylenetetrazol, remains unaltered in Cask+/- mice, indicating that even in mice the seizure phenotype is only partially penetrant and may have an indirect mechanism. RNA sequencing experiments on Cask+/- mouse brain uncovers a very limited number of changes, with most differences arising in the transcripts of extracellular matrix proteins and the transcripts of a group of nuclear proteins. In contrast to limited changes at the transcript level, quantitative whole-brain proteomics using iTRAQ quantitative mass-spectrometry reveals major changes in synaptic, metabolic/mitochondrial, cytoskeletal, and protein metabolic pathways. Unbiased protein-protein interaction mapping using affinity chromatography demonstrates that CASK may form complexes with proteins belonging to the same functional groups in which altered protein levels are observed. We discuss the mechanism of the observed changes in the context of known molecular function/s of CASK. Overall, our data indicate that the phenotypic spectrum of female Cask+/- mice includes sporadic seizures and thus closely parallels that of CASK haploinsufficient girls; the Cask+/- mouse is thus a face-validated model for CASK-related pathologies. We therefore surmise that CASK haploinsufficiency is likely to affect brain structure and function due to dysregulation of several cellular pathways including synaptic signaling and cellular metabolism.