scholarly journals Results of the search for anAboson decaying toZh, with anℓℓττfinal state, inppcollisions at 8 TeV centre of mass energy recorded with the ATLAS experiment

2015 ◽  
Vol 645 ◽  
pp. 012011
Author(s):  
Guillermo Nicolas Hamity
Keyword(s):  
Centre Of Mass ◽  
Mass Energy ◽  
Atlas Experiment ◽  
8 Tev

scholarly journals Commissioning the ATLAS Liquid Argon Calorimeter Phase-I Upgrade

2021 ◽  
Vol 253 ◽  
pp. 01007
Author(s):  
Ellis Kay
Keyword(s):  
Phase I ◽  
Liquid Argon ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Readout System ◽  
Total Luminosity ◽  
Precision Level ◽  
Level 1 ◽  
8 Tev ◽  
Electromagnetic Calorimetry

Liquid argon (LAr) sampling calorimeters are employed by ATLAS for all electromagnetic calorimetry in the pseudo-rapidity region η < 3.2, and for hadronic and forward calorimetry in the region from η = 1.5 to η = 4.9. In the first LHC run (Run-1), a total luminosity of around 26 fb-1 was collected at centre-of-mass energies of 7-8 TeV. After detector consolidation during a long shut-down, Run-2 started in 2015 and around 150 fb-1 of data at a centre-of-mass energy of 13 TeV was recorded. With the end of Run-2 in 2018, a multi-year shutdown for the Phase-I detector upgrades began. As part of the Phase-I upgrade, new trigger readout electronics of the ATLAS LAr Calorimeter have been developed. Installation be-gan at the start of the LHC shut down in 2019 and is expected to be completed in 2020. A commissioning cam-paign is underway in order to realise the capabilities of the new, higher granularity and higher precision level-1 trigger hardware in Run-3 data taking. This contribution will give an overview of the new trigger readout system and the ongoing commissioning and installation efforts.

scholarly journals Search for lepton-flavour-violating decays of the $Z$ boson into a $\tau$-lepton and a light lepton with the ATLAS detector

2019 ◽  
Author(s):  
Wing Sheung Chan
Keyword(s):  
Atlas Detector ◽  
Beyond The Standard Model ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Lepton Flavour Violation ◽  
Lepton Flavor ◽  
Upper Limits ◽  
Flavour Violation ◽  
8 Tev ◽  
Lepton Flavour

Lepton flavour violation in the charged lepton sector is an unambiguous signal of physics beyond the Standard Model. Searches for lepton flavour violation in decays of the ZZ boson with the ATLAS detector is reported, focusing on decays into an electron or muon and a hadronically decaying \tauτ-lepton, using pppp collisions data with a centre-of-mass energy of 13 TeV. Upper limits on the branching ratios of lepton-flavor-violating decays are set at the 95% confidence level: \mathcal{B}(Z\to e\tau) < 5.8\times10^{-5}ℬ(Z→eτ)<5.8×10−5 and \mathcal{B}(Z\to \mu\tau) < 2.4\times10^{-5}ℬ(Z→μτ)<2.4×10−5. When combined with a previous ATLAS result based on pppp collisions data with a centre-of-mass energy of 8 TeV, an upper limit of \mathcal{B}(Z\to \mu\tau) < 1.3\times10^{-5}ℬ(Z→μτ)<1.3×10−5 is obtained.

scholarly journals Cross-section measurements of final states with photons and jets with the ATLAS experiment

2018 ◽  
Vol 172 ◽  
pp. 02002
Author(s):  
Miguel Villaplana Pérez
Keyword(s):  
Cross Section ◽  
Transverse Energy ◽  
Atlas Collaboration ◽  
Final States ◽  
Coupling Constant ◽  
Centre Of Mass ◽  
Art Theory ◽  
Atlas Experiment ◽  
Renormalization Group Equations ◽  
8 Tev

The ATLAS Collaboration has performed precise measurements of the cross-section of final states with photons and/or jets at centre-of-mass energies of 8 and 13 TeV. The results are compared with state-of-the-art theory predictions and with predictions of several Monte Carlo generators. We also present new measurements of transverse energy-energy correlations and their associated asymmetries in multi-jet events at 8 TeV. Both measurements are used to extract the strong coupling constant and test the renormalization group equations.

scholarly journals The Fast Simulation Chain in the ATLAS experiment

2021 ◽  
Vol 251 ◽  
pp. 03012
Author(s):  
Martina Javurkova ◽  
Keyword(s):  
Monte Carlo ◽  
Simulated Data ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Production Chain ◽  
Proton Collisions ◽  
Atlas Experiment ◽  
Proton Proton Collisions ◽  
Significant Effort

The ATLAS experiment relies heavily on simulated data, requiring the production of billions of simulated proton-proton collisions every run period. As such, the simulation of collisions (events) is the single biggest CPU resource consumer. ATLAS’s finite computing resources are at odds with the expected conditions during the High Luminosity LHC era, where the increase in proton-proton centre-of-mass energy and instantaneous luminosity will result in higher particle multiplicities and roughly five-fold additional interactions per bunch-crossing with respect to LHC Run-2. Therefore, significant effort within the collaboration is being focused on increasing the rate at which Monte Carlo events can be produced by designing and developing fast alternatives to the algorithms used in the standard Monte Carlo production chain.

scholarly journals Measurement of J/ψ production cross-sections in pp collisions at $$ \sqrt{s} $$ = 5 TeV

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
◽  
R. Aaij ◽  
A. S. W. Abdelmotteleb ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
...  
Keyword(s):  
Cross Sections ◽  
Production Cross ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Nuclear Modification Factor ◽  
Theoretical Predictions ◽  
Modification Factor ◽  
8 Tev ◽  
Proton Proton Collisions

Abstract The production cross-sections of J/ψ mesons in proton-proton collisions at a centre-of-mass energy of $$ \sqrt{s} $$ s = 5 TeV are measured using a data sample corresponding to an integrated luminosity of 9.13 ± 0.18 pb−1, collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, pT, and rapidity, y, and separately for J/ψ mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised J/ψ mesons, the production cross-sections integrated over the kinematic range 0 < pT< 20 GeV/c and 2.0 < y < 4.5 are$$ {\displaystyle \begin{array}{c}{\sigma}_{\mathrm{prompt}}\ J/\psi =8.154\pm 0.010\pm 0.283\ \upmu \mathrm{b},\\ {}{\sigma}_{\mathrm{nonprompt}}\ J/\psi =0.820\pm 0.003\pm 0.034\ \upmu \mathrm{b},\end{array}} $$ σ prompt J / ψ = 8.154 ± 0.010 ± 0.283 μb , σ nonprompt J / ψ = 0.820 ± 0.003 ± 0.034 μb , where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at $$ \sqrt{s} $$ s = 8 TeV and 13 TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for J/ψ mesons at a centre-of-mass energy per nucleon pair of $$ \sqrt{s_{\mathrm{NN}}} $$ s NN = 5 TeV. The results are compared with theoretical predictions.

scholarly journals J/ψ production in proton-lead collisions at 8 TeV with the LHCb detector

2018 ◽  
Vol 171 ◽  
pp. 19001
Author(s):  
Oleksandr Okhrimenko
Keyword(s):  
Transverse Momentum ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Nucleon Pair ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Nuclear Modification ◽  
Lhcb Detector ◽  
Nuclear Modification Factors ◽  
8 Tev

The production of J/ψ mesons is studied in proton-lead collisions at a centre-of-mass energy per nucleon pair [see formula in PDF] = 8.16 TeV with the LHCb detector. The double differential cross-sections of prompt and nonprompt J/ψ production are measured as functions of the J/ψ transverse momentum and rapidity. Nuclear modification factors are determined. The results are compared with different theoretical calculations.

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