[en] SNiPER (Software for Non-collider Physics ExpeRiments) has been developed based on common requirements from both nuclear reactor neutrino and cosmic ray experiments. The design and implementation of SNiPER is described in this proceeding. Compared to the existing offline software frameworks in the high energy physics domain, the design of SNiPER is more focused on execution efficiency and flexibility. SNiPER has an open structure. User applications are executed as plug-ins based on it. The framework contains a compact kernel for software components management, event execution control, job configuration, common services, etc. Some specific features are attractive to non-collider physics experiments. (paper)

[en] The Jiangmen Underground Neutrino Observatory (JUNO) is a neutrino experiment to determine the neutrino mass hierarchy. It has a central detector used for neutrino detection, which consists of a spherical acrylic vessel containing a 20 kt liquid scintillator (LS) and about 18,000 20-inch photomultiplier tubes (PMTs) to collect light from LS. Around the central detector, there is a water pool to provide shielding from background radioactivity. The outer water pool is also equipped with about 2000 PMTs to measure cosmic ray muons by detecting Cherenkov light.

As one of the important parts in JUNO offline software, the serial simulation framework is developed based on SNiPER. It manages physics generator, detector simulation, event mixing and digitization. However, Geant4 based detector simulation of such a large detector is time-consuming and challenging. It is necessary to take full advantages of parallel computing to speed up simulation. Starting from version 10.0, Geant4 supports event-level parallelism. Even though this is based on pthread, it can be extended with other libraries such as Intel TBB and MPI. Therefore it is possible to parallelize JUNO simulation framework by integrating Geant4 and SNiPER.

In this paper, our progress in developing parallelized simulation software is presented. The SNiPER framework can run in sequential mode, Intel TBB mode or other modes. The SNiPER task component is in charge of the event loop, which is like a simplified application manager. Two types of tasks are introduced in the simulation framework, one is a global task and another is a worker task. The global task will run only once to initialize detector geometry and physics processes before any other tasks spawned. Later it is accessed by other tasks passively. The worker tasks will be spawned after the global task is done. In each worker task, a Geant4 run manager is invoked to do the real simulation. In this way the simulation framework and the underlying TBB have been decoupled. Finally, the software performance of parallelized JUNO simulation software is also presented. (paper)

[en] SNiPER is a general purpose offline software framework for high energy physics experiments. During the development, we pay more attention to the requirements of neutrino and cosmic ray experiments. And now it has been adopted by many experiments. It is necessary for us to implement parallel computing to improve the data processing efficiency. Intel Threading Building Blocks (TBB), as a powerful high level library, emancipates us from trivial and complex details of raw threads. In this proceeding, we implemented an event level parallel computing wrapper for the original serial SNiPER based on Intel TBB. We have taken parallel computing into account at the beginning of SNiPER’s design, it is possible to achieve multithreading in a non-invasive way. The SNiPER kernel module and Intel TBB are absolutely de-coupled. Features of multithreading are transparent to most users, except a few conventions such as global variables. This approach will significantly reduce the costs of migration from serial to parallel computing. However, it is more complicated for critical resources handling, such as disk I/O and memory management. There are also some attempts for these challenges. (paper)

[en] Using samples of 2.25x10⁸ J/ψ events and 1.06x10⁸ ψ^' events collected with the BES III detector, we study the f₀(980)→a₀⁰(980) and a₀⁰(980)→f₀(980) transitions in the processes J/ψ→φf₀(980)→φa₀⁰(980) and χ_c1→π⁰a₀⁰(980)→π⁰f₀(980), respectively. Evidence for f₀(980)→a₀⁰(980) is found with a significance of 3.4σ, while in the case of a₀⁰(980)→f₀(980) transition, the significance is 1.9σ. Measurements and upper limits of both branching ratios and mixing intensities are determined.

[en] Using a sample of (225.2±2.8)x10⁶ J/ψ events collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider, CP and P violating decays of η, η^', and η_c into π⁺π^- and π⁰π⁰ are searched for in J/ψ radiative decays. No significant η, η^', or η_c signal is observed, and 90% confidence level upper limits of B(η→π⁺π^-)<3.9x10^-4, B(η^'→π⁺π^-)<5.5x10^-5, B(η_c→π⁺π^-)<1.3x10^-4, B(η→π⁰π⁰)<6.9x10^-4, B(η^'→π⁰π⁰)<4.5x10^-4, and B(η_c→π⁰π⁰)<4.2x10^-5 are obtained.

[en] We present measurements of the charmonium state h_c(¹P₁) made with 106x10⁶ ψ^' events collected by BESIII at BEPCII. Clear signals are observed for ψ^'→π⁰h_c with and without the subsequent radiative decay h_c→γη_c. First measurements of the absolute branching ratios B(ψ^'→π⁰h_c)=(8.4±1.3±1.0)x10^-4 and B(h_c→γη_c)=(54.3±6.7±5.2)% are presented. A statistics-limited determination of the previously unmeasured h_c width leads to an upper limit Γ(h_c)<1.44 MeV (90% confidence). Measurements of M(h_c)=3525.40±0.13±0.18 MeV/c² and B(ψ^'→π⁰h_c)xB(h_c→γη_c)=(4.58±0.40±0.50)x10^-4 are consistent with previous results.

[en] With a sample of (225.2±2.8)x10⁶ J/ψ events registered in the BESIII detector, J/ψ→γπ⁺π^-η^' is studied using two η^' decay modes: η^'→π⁺π^-η and η^'→γρ⁰. The X(1835), which was previously observed by BESII, is confirmed with a statistical significance that is larger than 20σ. In addition, in the π⁺π^-η^' invariant-mass spectrum, the X(2120) and the X(2370), are observed with statistical significances larger than 7.2σ and 6.4σ, respectively. For the X(1835), the angular distribution of the radiative photon is consistent with expectations for a pseudoscalar.

[en] The decays ψ^'→γπ⁰, γη and γη^' are studied using data collected with the BESIII detector at the BEPCII e⁺e^- collider. The processes ψ^'→γπ⁰ and ψ^'→γη are observed for the first time with signal significances of 4.6σ and 4.3σ, respectively. The branching fractions are determined to be B(ψ^'→γπ⁰)=(1.58±0.40±0.13)x10^-6, B(ψ^'→γη)=(1.38±0.48±0.09)x10^-6, and B(ψ^'→γη^')=(126±3±8)x10^-6, where the first errors are statistical and the second ones systematic.

[en] Using a sample of 1.06x10⁸ ψ^' decays collected by the BESIII detector, χ_c0 and χ_c2 decays into π⁰π⁰ and ηη are studied. The branching fraction results are Br(χ_c0→π⁰π⁰)=(3.23±0.03±0.23±0.14)x10^-3, Br(χ_c2→π⁰π⁰)=(8.8±0.2±0.6±0.4)x10^-4, Br(χ_c0→ηη)=(3.44±0.10±0.24±0.2)x10^-3, and Br(χ_c2→ηη)=(6.5±0.4±0.5±0.3)x10^-4, where the uncertainties are statistical, systematic due to this measurement, and systematic due to the branching fractions of ψ^'→γχ_cJ. The results provide information on the decay mechanism of χ_c states into pseudoscalars.

[en] Using (106±4)x10⁶ ψ(3686) events accumulated with the BESIII detector at the BEPCII e⁺e^- collider, we present the first measurement of decays of χ_c1 to vector meson pairs φφ, ωω, and ωφ. The branching fractions are measured to be (4.4±0.3±0.5)x10^-4, (6.0±0.3±0.7)x10^-4, and (2.2±0.6±0.2)x10^-5, for χ_c1→φφ, ωω, and ωφ, respectively, which indicates that the hadron helicity selection rule is significantly violated in χ_cJ decays. In addition, the measurement of χ_cJ→ωφ provides the first indication of the rate of doubly OZI-suppressed χ_cJ decay. Finally, we present improved measurements for the branching fractions of χ_c0 and χ_c2 to vector meson pairs.