For Run 3, ATLAS redesigned its offline software, Athena, so that the main workflows run completely multithreaded. The resulting substantial reduction in the overall memory requirements allows for ...better use of machines with many cores. This note will discuss the performance achieved by the multithreaded reconstruction, the process of migrating the large ATLAS code base, and tools and techniques that were useful in debugging threading-related problems.
In the last year ATLAS has radically updated its software development infrastructure hugely reducing the complexity of building releases and greatly improving build speed, flexibility and code ...testing. The first step in this transition was the adoption of CMake as the software build system over the older CMT. This required the development of an automated translation from the old system to the new, followed by extensive testing and improvements. This resulted in a far more standard build process that was married to the method of building ATLAS software as a series of 12 separate projects from Subversion. We then proceeded with a migration of the code base from Subversion to Git. As the Subversion repository had been structured to manage each package more or less independently there was no simple mapping that could be used to manage the migration into Git. Instead a specialist set of scripts that captured the software changes across official software releases was developed. With some clean up of the repository and the policy of only migrating packages in production releases, we managed to reduce the repository size from 62 GiB to 220 MiB. After moving to Git we took the opportunity to introduce continuous integration so that now each code change from developers is built and tested before being approved. With both CMake and Git in place we also dramatically simplified the build management of ATLAS software. Many heavyweight homegrown tools were dropped and the build procedure was reduced to a single bootstrap of some external packages, followed by a full build of the rest of the stack. This has reduced the time for a build by a factor of 2. It is now easy to build ATLAS software, freeing developers to test compile intrusive changes or new platform ports with ease. We have also developed a system to build lightweight ATLAS releases, for simulation, analysis or physics derivations which can be built from the same branch.
This dissertation presents two analyses performed on data collected with the BABAR detector at the SLAC PEP-II e +e- asymmetric-energy B Factory. First, a Dalitz analysis is shown that performs the ...first measurement of CP violation parameters in the decay B - → Dπ+π-π 0 K- using the decay rate asymmetry and D0 - D 0 interference. The results can be used to further constrain the value of the CKM angle γ. The second analysis studies the properties of the X(3872) in neutral and charged B → J/ψπ+π-K decays. Measurements of the branching ratio and mass are presented as well as the search for additional resonances at higher masses.
Realizing the physics programs of the planned and upgraded high-energy physics (HEP) experiments over the next 10 years will require the HEP community to address a number of challenges in the area of ...software and computing. For this reason, the HEP software community has engaged in a planning process over the past two years, with the objective of identifying and prioritizing the research and development required to enable the next generation of HEP detectors to fulfill their full physics potential. The aim is to produce a Community White Paper which will describe the community strategy and a roadmap for software and computing research and development in HEP for the 2020s. The topics of event reconstruction and software triggers were considered by a joint working group and are summarized together in this document.
Realizing the physics programs of the planned and upgraded high-energy physics (HEP) experiments over the next 10 years will require the HEP community to address a number of challenges in the area of ...software and computing. For this reason, the HEP software community has engaged in a planning process over the past two years, with the objective of identifying and prioritizing the research and development required to enable the next generation of HEP detectors to fulfill their full physics potential. The aim is to produce a Community White Paper which will describe the community strategy and a roadmap for software and computing research and development in HEP for the 2020s. The topics of event reconstruction and software triggers were considered by a joint working group and are summarized together in this document.
Phys.Rev.D79:014026,2009 We describe a method for measuring CP-violation parameters from which the
Cabibbo-Kobayashi-Maskawa angle $\gamma$ may be extracted. The method makes use
of the total decay ...rates in $B^\pm \to DK^\pm$ decays, where the neutral $D$
meson decays to multibody final states. We analyze the error of the method
using experimental CP-violation analysis variables that enable straightforward
sensitivity comparison with other methods for extracting $\gamma$, and discuss
the use of $B$-factory and charm-factory data to obtain the relevant charm
decay information needed for this measurement. Measurement sensitivities are
estimated for the currently available $B$-factory data sample, and $D$ decay
modes for which use of this method can make a significant contribution toward
reducing the total error on $\gamma$ are identified.
We describe a method for measuring CP-violation parameters from which the Cabibbo-Kobayashi-Maskawa angle \(\gamma\) may be extracted. The method makes use of the total decay rates in \(B^\pm \to ...DK^\pm\) decays, where the neutral \(D\) meson decays to multibody final states. We analyze the error of the method using experimental CP-violation analysis variables that enable straightforward sensitivity comparison with other methods for extracting \(\gamma\), and discuss the use of \(B\)-factory and charm-factory data to obtain the relevant charm decay information needed for this measurement. Measurement sensitivities are estimated for the currently available \(B\)-factory data sample, and \(D\) decay modes for which use of this method can make a significant contribution toward reducing the total error on \(\gamma\) are identified.
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