Agenda of Etac Weekly Meeting

* Every Friday 10:00- at Main Bld, B324 link by skype: lulu_chenhx * Contact: Haixuan Chen

2007

*09/07 Each one's analysis channel is assigned preliminarily. S. X. Du: inclusive photon spectrum Q. Liu and H. X Chen: Ks K pi, pi+pi-pi+pi-, K+K-pi+pi- C. P. Shen : eta pipi, etap pipi F. Liu: omega phi, omega omega, phi phi M. Ablikim : p pbar K. Zhu : lambda lambdabar, gamma gamma X. R. Li: pi+pi-pi+pi-pi+pi-, K+K-pi+pi-pi+pi- P. L. Wang: eta KK, etap KK Many advices received: We should have a working plan for the BESIII annual meeting and Jan. 2008. The description of the signal shape (non. relative BW or relative BW) and the fitting method (binned or unbinned ) should be considered. How to consider the effects from detection efficiency in the unbinned fit? The tools for reconstruction of composed particles: Ks, Lambda, etc. All analysis works will be based on boss6.3.0 from now on. In order to save space and times, everyone's MC samples should be given description in the website. *09/19 S.X. Du gave a report on the check of single photon resolution from 30MeV to 500MeV, and show how to generate the MC sample including the cross angle of e+ e- beams, and how to include the McTruth information in the reconstructed data and read the McTruth information from reconstructed data(his report is attached). H.X. Chen gave a report on some checks based on boss6.3.0. The McTruth information can be read from the reconstructed inclusive sample, the Run Num. can not output and there is no ECM information. The psip->gamma etac, etac->4pi events are selected using 2M psip inclusive sample but there no obvious signal can be observed, the selection function should be optimized. Only 1909153 total events are found in the 2M psip inclusive samples. It is suggested that a channel with large branching ratio should be analyzed to check the inclusive MC sample. The results of exclusive channel are shown and many advices received. R.G.Ping gave a report on etac parameters fitting. He wrote a program for the fit using non-relativistic and relativistic BW, with the affects from detection efficiency and resolution considering. You can find the method to use it in his report.

Shuxian's report-1 Shuxian's report-2 Haixuan's report R.G.Ping's report

*10/10 There are four reports in this meeting. Q. Liu gave a report on analysis of etac->KKPiPi and 4Pi. It shows the efficiency 4C fit is about 60%, quite small than the all charged tracks channel, the reason need to be understand. Both Gaussian+polynomial and Double Gaussian shapes are used to fit the resolution of m4Pi, and the resolution is similar. The output values of mass and width of etac become closer to input values after 4C. The 4C efficiency is also low in etac->KKPiPi. And the NGAM distribution shows that there are much fake photons selected, it means the photon selection should be optimized. In both fits of the mass resolutions after 4C in KKPiPi and 4Pi, it can be seen that the data points in high mass region are general higher than the fit curve, it need to be understand. X. R. Li gave a report on the analysis of etac->6Pi. The efficiencies after PID and 4C are quite low and the etac signal is not observed from the 100M psip inclusive MC sample. M. Ablikim also showsn her results of etac->p pbar, the detection efficiency is similar to BESII. 4C fit is expected to be applied to see its effect on the detection efficiency. H.X.Chen shown some fit results of the etac->KsKPi, 4Pi based the new MC samples considering the CMS boost. Also the 4C fit is expected to be applied to see the effect.

Haixuan's report

*10/18 H. X. Chen shows the 4C efficiences etac to KsKPi and KKPiPi, 4C the efficiencies range from about 60 percent to 70 percent. From the energy distributions of radiative photon before and after 4C fit, it can be seen that there are many fake photons before the 4C fit. These fake photons may fail to pass through 4C fit and caused the decrease of detective efficiency. It is suggested to loss the photon selection or even miss the photon information to check the change of 4C efficiency. Medina also shows her results of jpsi->g etac, etac->p pbar. Results without CMS boost and with CMS boost are compared and the 4C efficiency is about 70%. K. Zhu give a report on his analysis of etac->Lambda Lambdar->p pbar pi+ pi-. The detection efficiency are low basing on the default reconstruction version of boss6.3.0 because the charged tracks from second vertex can not be reconstructed well. The efficiency become better when the reconstruction version of zangsl is used. It is strange that from the momentum distributions of pion and proton, it can be seen that these two distributions are overlap. Why there are few events with high momentum pion in the momentum distribution of pion. It need to understood.

Haixuan's report M. Ablikim's report Zhu K's report

*10/18 H. X. Chen shows the deposit energy distribution of neutral tracks and other angle information to check the select criteria of photon candidate. There is a little bump in the deposit energy distribution at 60MeV, the cause of it needs to be understand. R. G. Ping give a report on the line shape of eta_c and what has been considered in the etac fit program. The etac fit program has been updated. Please download the latest version in /epcfarm0/data22/pingrg/etac and check it using your data sample. F. Liu shows her results on the jpsi->g omega phi analysis. The efficiency of 5C fit decrease so much when change the environment from boss6.1.0 to boss 6.3.0. It is suggested to see whether the error matrix of photon is input correctly and find the reason of this low 5C efficiency. P.S. In boss.6.3.0, if there is no run.mac in the workarea/TestRelease/TestRelease-00-00-26/run/ when you check out and gmake the TestRelease package , please copy it at this director: /afs/ihep.ac.cn/bes3/offline/sw/dist/boss/6.3.0/Simulation/BOOST/BesSim/BesSim-00-00-41/share/run.mac *11/02 There are four reports in this meeting. C. P. Shen gave a report on the analysis of psip->gamma etac, etac->eta pi+ pi-, eta->gamma gamma base the MC simulation. Three methods are tried for the analysis: I.without kinematic fit, II. with 4C kinematic fit, III. with 5C kinematic. The fit of M_ggpi+pi- is not good and the give a detective efficiency of 15.6%.M_ggpi+pi- can be fit well using Double Gaussian and the detective efficiency is 18.48%. The branching fraction of psip->gamma etac measured using the 20M inclusive MC sample is consistence with the input value with large error. More inclusive MC sample is expected to be generated. From the polar angle distribution of etac, there are two decreases in the region cos_theta = +- (0.8-0.9), it may cause by the gap between the Barrel EMC and the Endcap EMC. 5c fit is also applied to the event selection by the detection efficiency is found to be quite low. The chi2 distribution for the PID using dE/dx and TOF seem not correct. According to the information got from Prof. Liu, the problem is solved in boss6.3.2. K. Zhu give gave a report on the analysis psip->gamma etac, etac->Lambda Lambdabar, and shows a method to get the proper FWHM using the histogram of the M_etac distribution. It is also suggested by that the momenta of proton and pion should be corrected to the second vertex of Lambda and Lambdabar. X. R. Li shows her fit results of etac->3(pi+pi-), it is suggested that a Double Gaussian should be used in the convolving. She found one event that the pions in this event with strange momentum (quite large) in her analysis, it is suggested that the reason of it should be find out ( such as using the MCTruth information). In the end R. G. Ping give a report on the line shape of eta_c, it is found from his calculation the systematic error caused by line shape is not negligible.

Chengping's report Ping Ronggang's report Zhu K's report Li XiuRong's report