Helium identification with LHCb

The identification of helium nuclei at LHCb is achieved using a method based on measurements of ionisation losses in the silicon sensors and timing measurements in the Outer Tracker drift tubes. The background from photon conversions is reduced using the RICH detectors and an isolation requirement. The method is developed using pp collision data at √(s) = 13 TeV recorded by the LHCb experiment in the years 2016 to 2018, corresponding to an integrated luminosity of 5.5 fb-1. A total of around 105 helium and antihelium candidates are identified with negligible background contamination. The helium identification efficiency is estimated to be approximately 50% with a corresponding background rejection rate of up to O(10^12). These results demonstrate the feasibility of a rich programme of measurements of QCD and astrophysics interest involving light nuclei

Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √sNN = 5.02 TeV with the LHCb detector

Flow harmonic coefficients, v n , which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV . The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features

Curvature-bias corrections using a pseudomass method

Momentum measurements for very high momentum charged particles, such as muons from electroweak vector boson decays, are particularly susceptible to charge-dependent curvature biases that arise from misalignments of tracking detectors. Low momentum charged particles used in alignment procedures have limited sensitivity to coherent displacements of such detectors, and therefore are unable to fully constrain these misalignments to the precision necessary for studies of electroweak physics. Additional approaches are therefore required to understand and correct for these effects. In this paper the curvature biases present at the LHCb detector are studied using the pseudomass method in proton-proton collision data recorded at centre of mass energy √(s)=13 TeV during 2016, 2017 and 2018. The biases are determined using Z→μ + μ - decays in intervals defined by the data-taking period, magnet polarity and muon direction. Correcting for these biases, which are typically at the 10-4 GeV-1 level, improves the Z→μ + μ - mass resolution by roughly 18% and eliminates several pathological trends in the kinematic-dependence of the mean dimuon invariant mass

Activities related to inflammatory bowel disease management during and after the coronavirus disease 2019 lockdown in Italy: How to maintain standards of care

Background and aims:Restructuring activities have been necessary during the lockdown phase of the coronavirusdisease 2019 (COVID-19) pandemic. Few data are available on the post-lockdown phase in terms of health-careprocedures in inflammatory bowel disease (IBD) care, and no data are available specifically from IBD units. Weaimed to investigate how IBD management was restructured during the lockdown phase, the impact of therestructuring on standards of care and how Italian IBD units have managed post-lockdown activities.Methods:A web-based online survey was conducted in two phases (April and June 2020) among the Italian Groupfor IBD affiliated units within the entire country. We investigated preventive measures, the possibility of continuingscheduled visits/procedures/therapies because of COVID-19 and how units resumed activities in the post-lockdownphase.Results:Forty-two referral centres participated from all over Italy. During the COVID-19 lockdown, 36% of first visitsand 7% of follow-up visits were regularly done, while>70% of follow-up scheduled visits and 5% of first visits weredone virtually. About 25% of scheduled endoscopies and bowel ultrasound scans were done. More than 80% ofbiological therapies were done as scheduled. Compared to the pre-lockdown situation, 95% of centres modifiedmanagement of outpatient activity, 93% of endoscopies, 59% of gastrointestinal ultrasounds and 33% of biologicaltherapies. Resumption of activities after the lockdown phase may take three to six months to normalize. Virtualclinics, implementation of IBD pathways and facilities seem to be the main factors to improve care in the future.Conclusion:Italian IBD unit restructuring allowed quality standards of care during the COVID-19 pandemic to bemaintained. A return to normal appears to be feasible and achievable relatively quickly. Some approaches, suchas virtual clinics and identified IBD pathways, represent a valid starting point to improve IBD care in the post-COVID-19 er