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 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.

scholarly journals Measurement of the shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ differential decay rate

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
R. Aaij ◽  
◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Decay Rate ◽  
Form Factors ◽  
Proton Collision ◽  
Centre Of Mass ◽  
Mass Energy ◽  
Proton Proton ◽  
Lhcb Detector ◽  
Proton Proton Collision ◽  
Integrated Luminosity

Abstract The shape of the $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ differential decay rate is obtained as a function of the hadron recoil parameter using proton-proton collision data at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.7 fb−1 collected by the LHCb detector. The $$ {B}_s^0\to {D}_s^{\ast -}{\mu}^{+}{\nu}_{\mu } $$ B s 0 → D s ∗ − μ + ν μ decay is reconstructed through the decays $$ {D}_s^{\ast -}\to {D}_s^{-}\gamma $$ D s ∗ − → D s − γ and $$ {D}_s^{-}\to {K}^{-}{K}^{+}{\pi}^{-} $$ D s − → K − K + π − . The differential decay rate is fitted with the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) parametrisations of the form factors, and the relevant quantities for both are extracted.

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