Deep Machine Learning for the PANDA Software Trigger

Deep machine learning methods have been studied for the software trigger of the future PANDA experiment at FAIR, using Monte Carlo simulated data from the GEANT-based detector simulation framework PandaRoot. Ten physics channels that cover the main physics topics, including electromagnetic, exotic, charmonium, open charm, and baryonic reaction channels, have been investigated at four different anti-proton beam momenta. Binary and multi-class classification together with seven different network architectures have been studied. Finally a residual convolutional neural network with four residual blocks in a binary classification scheme has been chosen due to its extendability, performance and stability. The presented study represents a feasibility study of a completely software-based trigger system. Compared to a conventional selection method, the deep machine learning approach achieved a significant efficiency gain of up to 200\%, while keeping the background reduction factor at the required level of 1/1000. Furthermore, it is shown that the use of additional input variables can improve the data quality for subsequent analysis. This study shows that the PANDA software trigger can benefit greatly from the deep machine learning methods.Comment: 13 pages, 9 figures, submitted for publication in EPJ-

Measurements of h_c(^1P_1) in psi' Decays

We present measurements of the charmonium state $h_c(^1P_1)$ made with 106M $\psi'$ events collected by BESIII at BEPCII. Clear signals are observed for $\psi'\to\pi^0 h_c$ with and without the subsequent radiative decay $h_c\to\gamma\eta_c$. First measurements of the absolute branching ratios $\mathcal{B}(\psi' \to\pi^0 h_c) = (8.4 \pm 1.3 \pm 1.0) \times 10^{-4}$ and $\mathcal{B}(h_c \to \gamma \eta_c) = (54.3 \pm 6.7 \pm5.2)$ are presented. A statistics-limited determination of the previously unmeasured $h_c$ width leads to an upper limit $\Gamma(h_c)<1.44$MeV (90% confidence). Measurements of $M(h_c) = 3525.40 \pm 0.13 \pm 0.18$MeV/$c^2$ and $\mathcal{B}(\psi'\to \pi^0 h_c) \times \mathcal{B}(h_c \to \gamma\eta_c) = (4.58 \pm 0.40 \pm 0.50) \times 10^{-4}$ are consistent with previous results.Comment: 5 pages, 1 figure, accepted for publication in Physical Review Letter

Untersuchung des Zerfalls Ds±→K+K−π+π−π±D_{s}^{\pm}\rightarrow K^{+}K^{-}\pi^{+}\pi^{-}\pi^{\pm}

Der am Speicherring PEP-II des Stanford Linear Accelerator Centers befindliche BABAR-Detektor bietet neben der Rekonstruktion von B-Mesonen zur Untersuchung der CP-Verletzung auch hervorragende Möglichkeiten zur Spektroskopie charmhaltiger Teilchen wie Ds-Mesonen. Bei der Untersuchung der Zerfallsraten schwerer Mesonen fällt auf, dass die Verzweigungsverhältnisse mit dem Axialvektormeson a1+ im Endzustand von gleicher Größenordnung sind wie die entsprechenden Werte mit dem Vektormeson rho+ im Endzustand. Diese Feststellung führt zur Hypothese einer Vektordominanz bei schwachen Zerfällen schwerer Mesonen. Beschrieben wird die Rekonstruktion der Zerfälle $D_{s}\rightarrow\phi\pi^{+}\pi^{-}\pi^{\pm}$ und $D_{s}\rightarrow\phi\pi^{\pm}$, sowie die Bestimmung des relativen Verzweigungsverhältnisses dieser beiden Zerfallskanäle. Die anschliessende Untersuchung der Resonanzstruktur des 3-Pion-Systems im erstgenannten Zerfallskanals zum Nachweis des Zerfalls $D_{s}\rightarrow\pi{}$ a1 führt zum Test des oben genannten Vektordominanzmodelles

Search for the Y(2175) in photoproduction at GlueX

Abstract. The Y(2175), recently renamed to ϕ(2170), is one of the rare exotic candidates connected to strangeonium as compared to the heavier charmonium-like and bottomonium-like exotic states. Originally observed in initial state radiation events by the BaBar experiment in 2006, it is suggested to be a strange partner state of the charmonium-like exotic vector state Y(4230) that was one of the first of the so-called XYZ states reported in the charmonium mass region. The Y(2175) has been seen in various experiments and decay channels,but it has not yet been searched for in a photo-production experiment. In this talk we report on a measurement of the production cross section of the reaction γ + p → ϕπ+ π− + p based on data recorded by the GlueX experiment in order to search for Y(2175) → ϕπ+π−.

Epitaxial Growth of pi Stacked Perfluoropentacene on Graphene Coated Quartz

Chemical vapor deposited large area graphene is employed as the coating of transparent substrates for the growth of the prototypical organic n type semiconductor perfluoropentacene PFP . The graphene coating is found to cause face on growth of PFP in a yet unknown substrate mediated polymorph, which is solved by combining grazing incidence X ray diffraction with theoretical structure modeling. In contrast to the otherwise common herringbone arrangement of PFP in single crystals and standing films, we report a amp; 960; stacked arrangement of coplanar molecules in flat lying films, which exhibit an exceedingly low amp; 960; stacking distance of only 3.07 , giving rise to significant electronic band dispersion along the amp; 960; stacking direction, as evidenced by ultraviolet photoelectron spectroscopy. Our study underlines the high potential of graphene for use as a transparent electrode in opto electronic applications, where optimized vertical transport through flat lying conjugated organic molecules is desire

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%