311 research outputs found
The search for rare decays of the Higgs boson with ATLAS and CMS
No full textThe Higgs-like boson discovered by the ATLAS and CMS collaborations is a candidate for the last unobserved particle predicted by the Standard Model (SM). The next experimental step is the measurement of its properties, most notably its couplings. This contribution will present the searches for the SM Higgs boson via decays in rare modes such as dimuon pairs, decays to Z or invisible decays
Distributed Analysis within the LHC computing Grid
No full textThe distributed data analysis using Grid resources is one of the funda-
mental applications in high energy physics to be addressed and realized
before the start of LHC data taking. The needs to manage the resources
are very high. In every experiment up to a thousand physicist will be
submitting analysis jobs into the Grid. Appropriate user interfaces and
helper applications have to be made available to assure that all users
can use the Grid without too much expertise in Grid technology. These
tools enlarge the number of Grid users from a few production adminis-
trators to potentially all participating physicists.
The GANGA job management system (http://cern.ch/ganga), devel-
oped as a common project between the ATLAS and LHCb experiments
provides and integrates these kind of tools. GANGA provides a sim-
ple and consistent way of preparing, organizing and executing analysis
tasks within the experiment analysis framework, implemented through
a plug-in system. It allows trivial switching between running test jobs
on a local batch system and running large-scale analyzes on the Grid,
hiding Grid technicalities.
We will be reporting on the plug-ins and our experiences of distributed
data analysis using GANGA within the ATLAS experiment and the
EGEE/LCG infrastructure. The integration and interaction with the
ATLAS data management system DQ2/DDM into GANGA is a key
functionality. In combination with the job splitting mechanism large
amounts of analysis jobs can be sent to the locations of data following
the ATLAS computing model. GANGA supports tasks of user analysis
with reconstructed data and small scale production of Monte Carlo
data
First results on Higgs boson searches (SM + MSSM) and prospects from ATLAS
No full textFirst results on Higgs boson searches (SM + MSSM) and prospects from ATLA
Study of B c + → J / ψ D s + and B c + → J / ψ D s ∗ + decays in pp collisions at √s = 13 TeV with the ATLAS detector
No full textA study of B+
c → J/ψD+
s and B+
c → J/ψD∗+
s decays using 139 fb−1 of integrated luminosity collected with the ATLAS detector from √
s = 13 TeV pp collisions
at the LHC is presented. The ratios of the branching fractions of the two decays to the
branching fraction of the B+
c → J/ψπ+ decay are measured: B(B+
c → J/ψD+
s
)/B(B+
c →
J/ψπ+) = 2.76 ± 0.47 and B(B+
c → J/ψD∗+
s
)/B(B+
c → J/ψπ+) = 5.33 ± 0.96. The ratio
of the branching fractions of the two decays is found to be B(B+
c → J/ψD∗+
s
)/B(B+
c →
J/ψD+
s
) = 1.93 ± 0.26. For the B+
c → J/ψD∗+
s decay, the transverse polarization fraction,
Γ±±/Γ, is measured to be 0.70 ± 0.11. The reported uncertainties include both the statistical and systematic components added in quadrature. The precision of the measurements
exceeds that in all previous studies of these decays. These results supersede those obtained
in the earlier ATLAS study of the same decays with √s = 7 and 8 TeV pp collision data. A
comparison with available theoretical predictions for the measured quantities is presented
Distributed Data Analysis in the ATLAS Experiment: Challenges and Solutions
No full textThe ATLAS experiment at the LHC at CERN is recording and simulating several 10's of PetaBytes of data per year. To analyse these data the ATLAS experiment has developed and operates a mature and stable distributed analysis (DA) service on the Worldwide LHC Computing Grid. The service is actively used: more than 1400 users have submitted jobs in the year 2011 and a total of more 1 million jobs run every week. Users are provided with a suite of tools to submit Athena, ROOT or generic jobs to the grid, and the PanDA workload management system is responsible for their execution. The reliability of the DA service is high but steadily improving; grid sites are continually validated against a set of standard tests, and a dedicated team of expert shifters provides user support and communicates user problems to the sites. This paper will review the state of the DA tools and services, summarize the past year of distributed analysis activity, and present the directions for future improvements to the system
Author Correction: A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery
No full textIn the version of this article initially published, the ATLAS Collaboration
author names, affiliations and acknowledgements were omitted and
have now been included in the HTML and PDF versions of the article
Measurement of the CP-violating phase φs in B0s → J/ψφ decays in ATLAS at 13 TeV
No full textA measurement of the B0
s → J/ψφ decay
parameters using 80.5 fb−1 of integrated luminosity collected with the ATLAS detector from 13 TeV proton–proton
collisions at the LHC is presented. The measured parameters include the CP-violating phase φs, the width difference
Δ Γs between the B0
s meson mass eigenstates and the average decay width Γs. The values measured for the physical
parameters are combined with those from 19.2 fb−1 of 7 and
8 TeV data, leading to the following:
φs = −0.087 ± 0.036 (stat.) ± 0.021 (syst.) rad
ΔΓs = 0.0657 ± 0.0043 (stat.) ± 0.0037 (syst.) ps−1
Γs = 0.6703 ± 0.0014 (stat.) ± 0.0018 (syst.) ps−1
Results for φs and ΔΓs are also presented as 68% confidence level contours in the φs–ΔΓs plane. Furthermore the
transversity amplitudes and corresponding strong phases are
measured. φs and ΔΓs measurements are in agreement with
the Standard Model predictions
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