Development of an online track finding algorithm for the Pˉ\bar{P}ANDA luminosity detector and search for the decay channel e+^{+}e−^{−} →\rightarrow h\it hc_{c}η\etaπ\pi+^{+}π\pi−^{−} at the center of mass energy of 4.6 GeV at BESIII

Das $\bar{P}$ANDA Experiment wird einen Antiprotonenstrahl mit hoher Präzision auf ein Protonentarget schicken. Zur Normierung der Messwerte dient der Luminositätsdetektor mit 4 Lagen von aktiven Silizium-Pixelsensoren. Um wenn nötig, nur eine Untermenge der großen gemessenen Datenmenge zu archivieren, wurde ein Algorithmus zum Auffinden der Spuren der elastisch gestreuten Antiprotonen entwickelt. Dieser wurde für eine GPU und CPU implementiert. Die Verarbeitungsgeschwindigkeit, die Effizienz und der Prozentsatz an Geisterspuren wurden verglichen. Im zweiten Teil dieser Arbeit wurde am e$^{+}$ e$^{−}$ Kollisionsexperiment BESIII nach einem neuen Charmoniumartigen Zustand gesucht. Hierzu wurde bei einer Schwerpunktsenergie von 4.6 GeV in der Reaktion e$^{+}$ e$^{−}$ $\rightarrow$ $\it h$$_{c}$$\eta$$\pi$$^{+}$ $\pi$$^{−}$ nach einer resonannten Struktur gesucht die im $\it h$$_{c}$$\eta$ Subsystem auftreten könnte. Da kein signifikantes Signal beobachtet wurde, wurde mit einer statistischen Sicherheit von 90% eine obere Grenze für die untersuchte Reaktion bestimmt

Hyperon signatures in the PANDA experiment at FAIR

We present a detailed simulation study of the signatures from the sequential decays of the triple-strange pbar p -> Ω+Ω- -> K+ΛbarK- Λ -> K+pbarπ+K-pπ- process in the PANDA central tracking system with focus on hit patterns and precise time measurement. We present a systematic approach for studying physics channels at the detector level and develop input criteria for tracking algorithms and trigger lines. Finally, we study the beam momentum dependence on the reconstruction efficiency for the PANDA detector

Amplitude analysis and branching fraction measurement of D+s→K−K+π+π0

Relative fractions and phases of the intermediate decays are determined. With the detection efficiency estimated by the results of the amplitude analysis, the branching fraction of Dþ s → K−Kþπþπ0 decay is measured to be ð5.42 0.10stat 0.17systÞ%

Study of the processes χcJ → Ξ−Ξ¯+ and Ξ0Ξ¯0

Using 448.1 × 106 ψ(3686) decays collected with the BESIII detector at the BEPCII e+e− storage rings, the branching fractions and angular distributions of the decays χcJ → Ξ−Ξ¯¯¯¯+ and Ξ0Ξ¯¯¯¯0 (J = 0, 1, 2) are measured based on a partial-reconstruction technique. The decays χc1 → Ξ0Ξ¯¯¯¯0 and χc2 → Ξ0Ξ¯¯¯¯0 are observed for the first time with statistical significances of 7σ and 15σ, respectively. The results of this analysis are in good agreement with previous measurements and have significantly improved precision

Search for an axion-like particle in radiative J/ψ decays

We search for an axion-like particle (ALP) a through the process ψ(3686)→π+π−J/ψ, J/ψ→γa, a→γγ in a data sample of (2.71±0.01)×109 ψ(3686) events collected by the BESIII detector. No significant ALP signal is observed over the expected background, and the upper limits on the branching fraction of the decay J/ψ→γa and the ALP-photon coupling constant gaγγ are set at 95% confidence level in the mass range of 0.165≤ma≤2.84GeV/c2. The limits on B(J/ψ→γa) range from 8.3×10−8 to 1.8×10−6 over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for 0.165≤ma≤1.468GeV/c2

Measurements of the center-of-mass energies of e+e- collisions at BESIII

During the 2016-17 and 2018-19 running periods, the BESIII experiment collected 7.5 fb -1 of e+e− collision data at center-of-mass energies ranging from 4.13 to 4.44 GeV. These data samples are primarily used for the study of excited charmonium and charmoniumlike states. By analyzing the di-muon process e+e− (γISR/FSR)µ -> +µ-, we measure the center-of-mass energies of the data samples with a precision of 0.6 MeV. Through a run-by-run study, we find that the center-of-mass energies were stable throughout most of the data-collection period