Agenda of Charmonium Weekly Meeting
* Every Thursday 8:30- at Main Bld Room A511 link by skype: pingrg * Contact: Ronggang Ping, Prof. Stephen L. Olsen
2007
*07/26 Abstract: The charmonium group held the first group meeting this morning. R.G. Ping presents the physics agenda for the analysis of a small psi(2S) data sample, and S. Olsen presents a proposal for studying the eta_c resonance parameter. The physics agenda is discussed in detail, and many comments are given by the participants. Before the BESIII collaboration web page is accessible, we sent these presentations to you to request your comments or suggestion. If you have physics topics about the data analysis, you are welcome to sent it to me. R. G. Ping's report Stephen L. Olsen's report *08/16 Abstract: 1.Which channels with the most priority to do analysis. The measurement of resonance parameter, especially eta_c, is suggested with the most priority to do analysis. The channels, psi(2S)->gamma eta_c and J/psi->gamma eta_c can be used to study eta_c resonance parameters in parallel. Now psi(2S)->gamma etac has been studied with Monte-Carlo simulation by Chen Hai-Xuan, but background and the fitting need improvement. Except for the exclusive decays of eta_c, the mass spectrum of inclusive photon from psi(2S) radiative transition is also suggested to do this analysis. For determination the events number and understanding the detector performance, psi(2S)->pi pi J/psi should be used to do analysis. In physics aspect, this channel is studied for tagging J/psi, as well as for searching for J/psi->invisible decay. 2. Inclusive Monte-Carlo data sample. Currently large MC sample generation is CPU consuming. For doing a precise measurement, the larger MC sample is essential for background studies. If a small psi(2S) data sample, e.g. 100M, is taken, the same larger MC sample, 100M, is suggested to be generated. The scheme to modify MC inclusive sample is suggested to close some channels if we only focus on the study of etac_c resonance parameter and pipi J/pis decay. One suggests that current MCtruth should add information about the topology of a decay (to add intermediate record). This is important for background study. *08/30 Abstract: 1.To form a work group to measure the eta_c resonance parameters (see ChangZheng talk). According to the proposal by ChangZheng, a work group to measure eta_c resonance parameters is formed. Postdoc Hai-Xuan Chen is assigned as the convener of this working group. The participants include Haixuan Chen (psi(2S)->gamma eta_c), Shuxian Du (inclusive photon spectrum), Qian Liu (J/psi-> gamma eta), Chenping Sheng (psi(2S),J/psi -> gamma eta_c), Fang Liu (J/psi->gamma eta_c->gamma omega phi), Medina Ablikim (J/psi->gamma eta_c), plus other new comers: Kai Zhu, Xiurong Li and Peilin Wang et al. OTHER BESIII COLLEAGES HAVING INTERESTING IN THIS MEASUMENTS ARE WELLCOME TO JOIN THE WORKING GROUP. For making a efficient work, the convener of this group should make a plan to organize the participants and to push this work forward, and to held a discussion every week, and to report to the charmonium group meeting about the progress and the problems encountered 2. K-short selection at BOSS 6.1.0. (see Haixuan's talk) According to Huanxuan's report, it seems that the K-short decay lengths are not consistent obtained from McTruth and the K-short construction after detector simulation. Some suggestions about the improvement on the decay length fitting are given. After this consideration, if the consistency still exists, it will be made a feedback to the MC group. 3. To select one person to help MC data production: Shuxian Du is assigned. Haixuan's report Changzheng's report *11/15 Abstract: There is one report showing the checks on 2M inclusive MC sample of Psi(2S) generated by lundcharm generator base on Boss6.3.2. The checks show that four runs are ended with problem and all the other runs are all OK. The numbers of run and event record can be read normal. The chi distribution from dedx PID of pion is reasonable in boss6.3.2. There are two bumps of truth mass of pion, kaon and proton got from the inclusive MC sample. The differences between them are small but need to be understood. PS: Z. Y. Deng said that the mother() information of McParticle can not be used in the reconstructed MC sample but can be used in the simulated MC sample, because the related information were not written to the reconstructed MC sample in the procedure of reconstruction. This situation has been told to Prof. Li Weidong. But there is another way to judge the mother particle's character and I am trying it. *11/21 *12/05 *12/19 H. X. Chen gave a report on the consideration of the systematic error estimate on the etac mass measurement and shows that fitting program now used BWconvDgausPdf.cxx having the problem on Breit Wigner convolving double Gaussian. As to the mass calibration of etac, beside J/psi meson, it is suggested that Chi_cJ mesons can be used to doing a MC check. (C. P. Shen said that he use the convolution included in RooFit Package can get the good result of etac mass and width.) K. Zhu gave a report on the description of the shape of detection resolution of etac and gave a convolution function of BW convolving COB (BW convolving Gaussian). It is suggested that when describe resolution of etac, it need to compare the situation with narrower fitted mass region of etac, and the definition of the convolution in the COB, single side integral is used, it may cause the problem. Y. P. Guo gave a report on the MC analysis of psip->g etac, etac-> Ks K+pi-pi+pi-. The detection efficiency is 4.13% before 4C fit. It is suggested to see the decrease of each cut before 4C fit.Chen Haixuan's report Zhu Kai's report
2008
*03/06 The talks and minute are available at web site http://indico.ihep.ac.cn/categoryDisplay.py?categId=52. Two topics are given. They are about the comparison of the BOSS6.3.1 and 6.3.2. Chen HaiXuan talk about the MC simulation of psi(2S)->gamma etac, etac->2(pi+pi-) with BOSS6.3.1 and 6.3.2. She found that the distribution of the good charge tracks and photons with BOSS6.3.1 appears worse than the previous version BOSSS6.3.2. Zhu Kai talk about the simulation of psi(2S)->gamma etac, etac->Lambda Lambda bar with BOSS6.3.2 and 6.3.1, it is found that the distribution of photon energy from EMC is incorrect with 6.3.1 version, while it is right with 6.3.2 version. For details, see their talks. We suggest that the software people check the released 6.3.1 version to find out what cause this problem.