Determination of Strange Sea Quark Distributions from Fixed-target and Collider Data

We present an improved determination of the strange sea distribution in the nucleon with constraints coming from the recent charm production data in neutrino-nucleon deep-inelastic scattering by the NOMAD and CHORUS experiments and from charged current inclusive deep-inelastic scattering at HERA. We demonstrate that the results are consistent with the data from the ATLAS and the CMS experiments on the associated production of $W^\pm$-bosons with $c$-quarks. We also discuss issues related to the recent strange sea determination by the ATLAS experiment using LHC collider data.Comment: 23 pages, 14 figure

ATLAS Electroweak Measurements with early data

The study of electroweak physics with early data is a crucial task for ATLAS: W and Z Bosons are produced with clear signatures and high statistics. An analysis of their production properties allows tests of our understanding of the Standard Model in the kinematic regime of the LHC and can be used to determine the performance of the ATLAS detector. The talk presents electroweak measurements such as the cross section production of W and Z bosons, their ratios and asymmetries and explains how W and Z events can be used to probe the performance of the detector. Here, in particular the determinations of lepton trigger, identification and charge efficiencies, lepton-energy and missing-ET scales and resolutions as well as QCD backgrounds from fake electrons are considered

Local Hadronic Calibration of Single Pion Data from the Combined ATLAS Testbeam of 2004

For the first time, the local hadronic calibration scheme has been applied to real data from the combined test beam of 2004. In this note, the performance of the weighting of the combined test beam data is shown in relation to Monte Carlo simulations. The performance of the local calibration scheme when applied to simulated jets in full ATLAS set-up has also been demonstrated, and compared with the current default jet calibration, the "global" method. The local hadronic calibration achieves a calorimeter linearity within 3%, and the linearities of simulation and test beam data after weighting are in agreement. The calibration improves the resolution of simulated test beam data for beam energies larger than 8 GeV, and energies larger than 20 GeV for the data. In addition, the local hadronic calibration is shown to be a stable method for compensating the calorimeter system of ATLAS

Novel ideas for the high luminosity phase of the LHC

Without doubt, the High Luminosity Large Hadron Collider (HL-LHC) is one of the major projects in particle physics at the high energy frontier in the upcoming decades. Planned to come into operation mid-2027 it will substantially increase the amount of proton-proton collisions at 14 TeV delivered to the LHC experiments with a planned integrated luminosity of 3000 fb−1 for both ATLAS and CMS experiments, 50 fb−1 for LHCb, and 5 fb−1 for ALICE. The delivery of Pb–Pb and p–Pb collisions with integrated luminosities of 13 nb−1 and 50 nb−1 is foreseen, yielding an increase by a factor of up to twenty compared to the currently available data of Run-1 and Run-2

Geography of genetic structure in barley wild relative Hordeum vulgare subsp. spontaneum in Jordan

Informed collecting, conservation, monitoring and utilization of genetic diversity requires knowledge of the distribution and structure of the variation occurring in a species. Hordeum vulgare subsp. spontaneum (K. Koch) Thell., a primary wild relative of barley, is an important source of genetic diversity for barley improvement and co-occurs with the domesticate within the center of origin. We studied the current distribution of genetic diversity and population structure in H. vulgare subsp. spontaneum in Jordan and investigated whether it is correlated with either spatial or climatic variation inferred from publically available climate layers commonly used in conservation and ecogeographical studies. The genetic structure of 32 populations collected in 2012 was analyzed with 37 SSRs. Three distinct genetic clusters were identified. Populations were characterized by admixture and high allelic richness, and genetic diversity was concentrated in the northern part of the study area. Genetic structure, spatial location and climate were not correlated. This may point out a limitation in using large scale climatic data layers to predict genetic diversity, especially as it is applied to regional genetic resources collections in H. vulgare subsp. spontaneum

On direct measurement of the W production charge asymmetry at the LHC

The prospects for making a direct measurement of the W production charge asymmetry at the LHC are discussed. A modification to the method used at the Tevatron is proposed for measurements at the LHC. The expected sensitivity for such a measurement to parton distribution functions is compared to that for a measurement of the lepton charge asymmetry. The direct measurement approach is found to be less useful for placing constraints on parton distribution functions at the LHC than a measurement of the lepton charge asymmetry.Comment: 18 pages, 10 figures, v2: references and keywords updated v3: Additional paragraph discussing inclusion of W asymmetry in global fits adde

The upgraded microstrip silicon sensor characterisation facility of the University of Sheffield

A major component of the ATLAS Phase-II upgrade is the Inner Tracker, an all-silicon detector featuring novel microstrip sensors. Motivated by the current research efforts in silicon sensor technology, a characterisation facility has been recently upgraded at the University of Sheffield. A description of the facility along with initial benchmark measurements of sensors before and after their irradiation are presented. The results were found to be in agreement with similar measurements conducted by other facilities in the UK and support the successful commissioning of the facility

Constraints for the nuclear parton distributions from Z and W production at the LHC

The LHC is foreseen to finally bring also the nuclear collisions to the TeV scale thereby providing new possibilities for physics studies, in particular related to the electro-weak sector of the Standard Model. We study here the Z and W production in proton-lead and lead-lead collisions at the LHC, concentrating on the prospects of testing the factorization and constraining the nuclear modifications of the parton distribution functions (PDFs). Especially, we find that the rapidity asymmetries in proton-nucleus collisions, arising from the differences in the PDFs between the colliding objects, provide a decisive advantage in comparison to the rapidity-symmetric nucleus-nucleus case. We comment on how such studies will help to improve our knowledge of the nuclear PDFs.Comment: The version accepted for publication in JHEP. New figures has been added, and we also discuss the single charged lepton productio

Prototyping of petalets for the Phase-II Upgrade of the silicon strip tracking detector of the ATLAS Experiment

In the high luminosity era of the Large Hadron Collider, the HL-LHC, the instantaneous luminosity is expected to reach unprecedented values, resulting in about 200 proton-proton interactions in a typical bunch crossing. To cope with the resultant increase in occupancy, bandwidth and radiation damage, the ATLAS Inner Detector will be replaced by an all-silicon system, the Inner Tracker (ITk). The ITk consists of a silicon pixel and a strip detector and exploits the concept of modularity. Prototyping and testing of various strip detector components has been carried out. This paper presents the developments and results obtained with reduced-size structures equivalent to those foreseen to be used in the forward region of the silicon strip detector. Referred to as petalets, these structures are built around a composite sandwich with embedded cooling pipes and electrical tapes for routing the signals and power. Detector modules built using electronic flex boards and silicon strip sensors are glued on both the front and back side surfaces of the carbon structure. Details are given on the assembly, testing and evaluation of several petalets. Measurement results of both mechanical and electrical quantities are shown. Moreover, an outlook is given for improved prototyping plans for large structures.Comment: 22 pages for submission for Journal of Instrumentatio

Local Hadronic Calibration

The scheme of the hadronic calibration is discussed. Based on the cluster reconstruction an effective noise suppression is achieved. In a first step clusters are classified as electromagnetic or hadronic clusters. The weighting scheme to correct for the different e/pion response in the ATLAS calorimeter is presented. Dead material corrections and out of cluster corrections yield finally a signal which is rather close to the energy deposited by the final state particles in the ATLAS calorimeter. The constants and algorithms are derived from single pion MC studies and tested with jets. The validation of the scheme using testbeam data is presented as well