scholarly journals Operation and performance of the ATLAS semiconductor tracker in LHC Run 2

2022 ◽  
Vol 17 (01) ◽  
pp. P01013
Author(s):  
Georges Aad ◽  
Brad Abbott ◽  
Dale Charles Abbott ◽  
Adam Abed Abud ◽  
Kira Abeling ◽  
...  
Keyword(s):  
Hadron Collider ◽  
Proton Collision ◽  
Original Design ◽  
Proton Proton ◽  
Pile Up ◽  
Proton Proton Collision ◽  
And Performance ◽  
Full Depletion ◽  
The Impact ◽  
Integrated Luminosity

Abstract The semiconductor tracker (SCT) is one of the tracking systems for charged particles in the ATLAS detector. It consists of 4088 silicon strip sensor modules. During Run 2 (2015–2018) the Large Hadron Collider delivered an integrated luminosity of 156 fb-1 to the ATLAS experiment at a centre-of-mass proton-proton collision energy of 13 TeV. The instantaneous luminosity and pile-up conditions were far in excess of those assumed in the original design of the SCT detector. Due to improvements to the data acquisition system, the SCT operated stably throughout Run 2. It was available for 99.9% of the integrated luminosity and achieved a data-quality efficiency of 99.85%. Detailed studies have been made of the leakage current in SCT modules and the evolution of the full depletion voltage, which are used to study the impact of radiation damage to the modules.

scholarly journals Assessment of the performance of High-Luminosity LHC operational scenarios: integrated luminosity and effective pile-up density

2019 ◽  
Vol 97 (5) ◽  
pp. 498-508 ◽  
Author(s):  
L. Medina ◽  
R. Tomás ◽  
G. Arduini ◽  
M. Napsuciale
Keyword(s):  
Hadron Collider ◽  
High Luminosity ◽  
Reduced Cross Section ◽  
Proton Proton ◽  
Density Control ◽  
Pile Up ◽  
Alternative Scenarios ◽  
New Perspective ◽  
The Impact ◽  
Integrated Luminosity

The High-Luminosity Large Hadron Collider (HL-LHC) experiments will operate at unprecedented levels of event pile-up from proton–proton collisions at 14 TeV centre-of-mass energy. In this paper, we study the performance of the baseline and a series of alternative scenarios in terms of the delivered integrated luminosity and its quality (pile-up density). A new figure-of-merit is introduced, the effective pile-up density, a concept that reflects the expected detector efficiency in the reconstruction of event vertices for a given operational scenario, acting as a link between the machine and experimental sides. Alternative scenarios have been proposed either to improve the baseline performance or to provide operational schemes in the case of particular limitations. Simulations of the evolution of their optimum fills with the latest set of parameters of the HL-LHC are performed with β*-levelling, and the results are discussed in terms of both the integrated luminosity and the effective pile-up density. The crab kissing scheme, a proposed scenario for pile-up density control, is re-evaluated under this new perspective with updated beam and optics parameters. Estimates on the expected integrated luminosity due to the impact of crab cavity noise, full crab crossing, and reduced cross section for burn-off, are also presented.

scholarly journals UPDATED CONSTRAINTS ON HEAVY RESONANCES USING THE RUN 2 DATA AT LHC

2021 ◽  
Vol 34 ◽  
pp. 18-22
Author(s):  
A.A. Pankov ◽  
I.A. Serenkova ◽  
V.A. Bednyakov
Keyword(s):  
Hadron Collider ◽  
Proton Collision ◽  
Data Set ◽  
Proton Proton ◽  
Electroweak Gauge Boson ◽  
Heavy Resonances ◽  
Vector Bosons ◽  
Proton Proton Collision ◽  
8 Tev ◽  
Integrated Luminosity

The full ATLAS and CMS Run 2 data set at the Large Hadron Collider (LHC) with time- integrated luminosity of 139 fb −1 and 137 fb −1 , re- spectively, in the diboson channel is used to probe benchmark models with extended gauge sectors: theE 6 -motivated Grand Unification models, the left-right symmetric LR and the sequential standard model. These all predict neutral Z' and charged W' vector bosons, decaying into lepton or electroweak gauge boson pairs. We present constraints on the parameter space of the Z' and W' and compare them to those obtained from the previous analyses performed withLHC data collected at 7 and 8 TeV in Run 1 as well as at 13 TeV in Run 2 at time-integrated luminosity of 36.1 fb −1 . We show that proton-proton collision data at √ s = 13 TeV collected by the ATLAS and the CMS experiments allow to set the most stringent bounds to date on Z-Z' and W-W' mixing.

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.

scholarly journals Measurement of cross sections and couplings of the Higgs boson in fermionic decay modes with the ATLAS detector

2018 ◽  
Vol 182 ◽  
pp. 02119
Author(s):  
Liaoshan Shi
Keyword(s):  
Higgs Boson ◽  
Large Hadron Collider ◽  
Cross Sections ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Proton Proton Collision ◽  
The Cross

In this report, we present the latest ATLAS results on the measurement of the cross sections and couplings of the Higgs boson in the fermionic decay modes, H → μ+μ-, H → τ+τ- and H → bb. The searches are performed with proton-proton collision data delivered by the Large Hadron Collider during Run 1 and the first two years of Run 2 at √s = 7, 8 and 13 TeV.

scholarly journals Real-time data analysis model at LHC and connections to other experiments and fields

2020 ◽  
Vol 245 ◽  
pp. 11005
Author(s):  
Arantza Oyanguren
Keyword(s):  
Real Time ◽  
Hadron Collider ◽  
Proton Collision ◽  
Analysis Model ◽  
Time Analysis ◽  
Time Data ◽  
Proton Proton ◽  
Real Time Analysis ◽  
Real Time Data ◽  
Proton Proton Collision

With the upcoming increase of proton-proton collision rates at the Large Hadron Collider (LHC) experiments, and the corresponding increase of data volumes, real-time analysis becomes a key ingredient to be able to analyse and select the interesting data within the available computing resources. In this talk I will review the main features of the techniques followed by the ATLAS, CMS and LHCb experiments. Similar challenges have to be faced in other fields, such as astronomy and cosmology, and I will comment about them.

scholarly journals Study of $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ decays to charmonia and three light hadrons

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
◽  
R. Aaij ◽  
A. S. W. Abdelmotteleb ◽  
C. Abellán Beteta ◽  
F. J. Abudinen Gallego ◽  
...  
Keyword(s):  
Branching Fractions ◽  
Theoretical Description ◽  
Proton Collision ◽  
Proton Proton ◽  
Decay Modes ◽  
Charged Hadrons ◽  
Lhcb Detector ◽  
Proton Proton Collision ◽  
First Time ◽  
Integrated Luminosity

Abstract Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb−1 collected with the LHCb detector, seven decay modes of the $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + meson into a J/ψ or ψ(2S) meson and three charged hadrons, kaons or pions, are studied. The decays $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → (ψ(2S) → J/ψπ+π−)π+, $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → ψ(2S)π+π−π+, $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → J/ψK+π−π+ and $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → J/ψK+K−K+ are observed for the first time, and evidence for the $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + → ψ(2S)K+K−π+, decay is found, where J/ψ and ψ(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different $$ {\mathrm{B}}_{\mathrm{c}}^{+} $$ B c + decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.

scholarly journals Search for R-parity-violating supersymmetry in a final state containing leptons and many jets with the ATLAS experiment using $$\sqrt{s} = 13\hbox { TeV}$$ proton–proton collision data

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
G. Aad ◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
K. Abeling ◽  
...  
Keyword(s):  
Machine Learning ◽  
Hadron Collider ◽  
Data Driven ◽  
Machine Learning Techniques ◽  
Proton Collision ◽  
Top Squark ◽  
Proton Proton ◽  
Atlas Experiment ◽  
Background Estimation ◽  
Proton Proton Collision

AbstractA search for R-parity-violating supersymmetry in final states characterized by high jet multiplicity, at least one isolated light lepton and either zero or at least three b-tagged jets is presented. The search uses $${139}\,{\text {fb}^{-1}}$$ 139 fb - 1 of $$\sqrt{s} = {13}\hbox { TeV}$$ s = 13 TeV proton–proton collision data collected by the ATLAS experiment during Run 2 of the Large Hadron Collider. The results are interpreted in the context of R-parity-violating supersymmetry models that feature gluino production, top-squark production, or electroweakino production. The dominant sources of background are estimated using a data-driven model, based on observables at medium jet multiplicity, to predict the b-tagged jet multiplicity distribution at the higher jet multiplicities used in the search. Machine-learning techniques are used to reach sensitivity to electroweakino production, extending the data-driven background estimation to the shape of the machine-learning discriminant. No significant excess over the Standard Model expectation is observed and exclusion limits at the 95% confidence level are extracted, reaching as high as 2.4 TeV in gluino mass, 1.35 TeV in top-squark mass, and 320 (365) GeV in higgsino (wino) mass.

scholarly journals Searches for supersymmetry with the CMS experiment

2018 ◽  
Vol 182 ◽  
pp. 02060
Author(s):  
Alexis Kalogeropoulos ◽  
Keyword(s):  
Proton Collision ◽  
Proton Proton ◽  
Cms Experiment ◽  
Proton Proton Collision ◽  
Integrated Luminosity

We report on recent results by the CMS Collaboration on searches for supersymmetry based on a sample of proton-proton collision data at √s = 13 TeV, corresponding to a total integrated luminosity of 35.9 fb-1.

scholarly journals Measurements of the Higgs boson inclusive and differential fiducial cross sections in the 4$$\ell $$ decay channel at $$\sqrt{s}$$ = 13 TeV

2020 ◽  
Vol 80 (10) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Cross Sections ◽  
Decay Channel ◽  
Standard Model Prediction ◽  
Hadron Collider ◽  
Proton Collision ◽  
Proton Proton ◽  
The Standard Model ◽  
Proton Proton Collision

AbstractInclusive and differential fiducial cross sections of the Higgs boson are measured in the $$H \rightarrow ZZ^{*} \rightarrow 4\ell $$ H → Z Z ∗ → 4 ℓ ($$\ell = e,\mu $$ ℓ = e , μ ) decay channel. The results are based on proton−proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, equivalent to an integrated luminosity of 139 $$\hbox {fb}^{-1}$$ fb - 1 . The inclusive fiducial cross section for the $$H \rightarrow ZZ^{*} \rightarrow 4\ell $$ H → Z Z ∗ → 4 ℓ process is measured to be $$\sigma _\mathrm {fid} = 3.28 \pm 0.32$$ σ fid = 3.28 ± 0.32  fb, in agreement with the Standard Model prediction of $$\sigma _\mathrm {fid, SM} = 3.41 \pm 0.18 $$ σ fid , SM = 3.41 ± 0.18  fb. Differential fiducial cross sections are measured for a variety of observables which are sensitive to the production and decay of the Higgs boson. All measurements are in agreement with the Standard Model predictions. The results are used to constrain anomalous Higgs boson interactions with Standard Model particles.

scholarly journals Searches for exotic phenomena with the ATLAS detector

2015 ◽  
Vol 39 ◽  
pp. 1560094
Author(s):  
Patrick Czodrowski
Keyword(s):  
Large Hadron Collider ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Proton Collision ◽  
Proton Proton ◽  
Atlas Experiment ◽  
Proton Proton Collision ◽  
New Phenomena

Recent results of searches for exotic phenomena (new phenomena other than Supersymmetry) with the ATLAS experiment at the Large Hadron Collider conducted with proton–proton collision data at [Formula: see text][Formula: see text]TeV taken 2012 were presented.

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