Charmonium and Exotics Working Group Meeting
: May 9, 2014
: Bertram Kopf, Diego Bettoni, Dima Melnychuk, Elisa Fioravanti, Frank Nerling, Klaus Götzen, Malte Albrecht, Matthias Steinke, Paola Gianotti, Ralf Kliemt, Stefano Spataro, Torsten Schröder
In the beginning of the meeting Marc was addressing general issues. Zhiquin will not be able to work on the study for spin-exotic charmonium hybrid in production before June. Since the deadline for the scrutiny report is end of this month, the results of this study will not be included in the report. However, the channel was studied in detail in the physics book. These studies show, that it is very challenging and not feasible with the reduced luminosity scenarios. In addition, searches for charmonium hybrids in other production channels with a similar event topology are currently under study for the scrutiny report. So there is no urgent need to find a replacement and the group will continue what has started so far.
Torsten presented his analysis on glueball searches in pbar p -> K+ K- pi0 and K+ K- pi0 pi0 at beam momenta of 2 and 15 GeV
/c2. Beside the signal significance the angular distributions will define the figure of merit for this analysis. Larger background samples including further, strong background channels will be generated. The efforts will be prioritrized in the way that K+ K- pi0 channel at 2 GeV
/c will be studied first. Torsten will check if generic DPM samples are available at GSI.
Frank summarized the status of the analyses at GSI, which are focusing on search for exotic charmonium states. So far pbar p -> J/psi pi+ pi- and pbar p -> eta_c pi+ pi- have been investigated. A larger DPM background sample was generated. The signal significance is defined as the figure of merit. Based on the time to reach a significance of 5 the channels can be categorized as feasible or not with the given luminosity. The proposed categorization scheme was accepted by the group to be used for the other channels. However, the minimal required number of reconstructed events should also be taken into account, which can shift the required time upwards. The next step would be to study different detector setups and then add other recoil systems.
Dima presented the status of the h_c mass and width measurement in h_c -> eta_c gamma. The simulation has been performed previously for the physics book. The efficiency obtained in FastSim
is about a factor of two higher than for the previous study. Split-offs, which are not accounted for in the FastSim
, could be the reason for the observed deviation. Dima will investigate this issue. Klaus will check if it is possible to include a parameterization for split-offs into the FastSim
Elisa gave an update about the chi_c analysis. The amplitude parameters extracted from the analysis are in good agreement with the input to the simulation, providing a figure of merit for this channel. Elisa will now include background channels and study different detector options.
In the discussion after Torsten's talk Stefano as representative of the Computing Group was asked to investigate the possibility to run the simulation and analysis together without persisting the generated events. Considering the I/O overhead this approach could be faster and would be less strorage demanding.
The next meeting will be on Friday, May 16 at 11:30 am.
Material for discussion
- 08 May 2014