110680496
Beam test of a full-length prototype of the BESIII drift chamber with the readout electronics
A full-length prototype of the BESIII drift chamber together with its readout electronics was built and a beam test was performed. Two different methods, namely "single-threshold method" and "double-threshold method" for timing measurement, were studied. Test results show that the BESIII drift chamber and its readout electronics can reach their design specifications. The "double-threshold method" results in a better timing accuracy and noise suppression capabilities as compared with the "single-threshold method". (c) 2006 Elsevier B.V. All rights reserved.
36972437
The architecture of BESIII offline database
This paper presents the BESIII Offline Database for use in the current BESIII experiment at IHEP. The database can be used for the purpose of offline and physical analysis. It manages the history status data of detectors, electronics, slow control subsystem, and online subsystem. These are the data necessary for the online DQM monitor, reconstruction, calibration and data analysis. BESIII offline database also be used to manage calibration data, DQM data and Monte Carlo data. These are also the data necessary for the data analysis. The BESIII database also provide user with web services to make it possible to monitor the status of detectors, slow control subsystem, and online subsystem locally or remotely. The database engine is MySQL server. The database technology route and the database services for the distributed application environment are also presented in this paper.
116994417
Measurement of $\eta^\prime\rightarrow \pi^+\pi^- e^+e^-$ and $\eta^\prime\rightarrow \pi^+\pi^-\mu^+\mu^-$
Based on a sample of 225.3 million J/\psi events accumulated with the BESIII detector at the BEPCII, the decays of \eta' to pi+pi-l+l- are studied via J/\psi to \gamma\eta'. A clear \eta' signal is observed in the pi+pi-e+e- mass spectrum, and the branching fraction is measured to be \BR(\eta' to pi+pi-e+e-) = (2.11\pm0.12 (stat.)\pm0.15 (syst.))\times10^{-3}, which is in good agreement with theoretical predictions and the previous measurement, but is determined with much higher precision. No \eta' signal is found in the pi+ pi- mu+ mu- mass spectrum, and the upper limit is determined to be \BR(\eta' to pi+ pi- mu+ mu-)<2.9\times10^{-5} at the 90% confidence level.
123325671
BESIII track fitting algorithm
A track fitting algorithm based on the Kalman filter method has been developed for BESⅢ of BEPCⅡ. The effects of multiple scattering and energy loss when the charged particles go through the detector, non-uniformity of magnetic field (NUMF) and wire sag, etc., have been carefully handled. This algor...
119274043
Partial wave analysis of $J/\psi \to \gamma \eta \eta$
Based on a sample of $2.25\times 10^{8}$ $J/\psi$ events collected with the BESIII detector at BEPCII, a full partial wave analysis on $J/\psi\to\gamma\eta\eta$ was performed using the relativistic covariant tensor amplitude method. The results show that the dominant $0^{++}$ and $2^{++}$ components are from the $f_0(1710)$, $f_0(2100)$, $f_0(1500)$, $f_2'(1525)$, $f_2(1810)$ and $f_2(2340)$. The resonance parameters and branching fractions are also presented.
12149444
Observation of a Near-Threshold Enhancement in the p-anti-p Mass Spectrum from Radiative J/psi --> gamma-p-anti-p Decays
We observe a narrow enhancement near 2m{sub p} in the invariant mass spectrum of p{bar p} pairs from radiative J/{psi} {yields} {gamma}p{bar p} decays. No similar structure is seen in J/{psi} {yields} {pi}{sup 0} p{bar p} decays. The results are based on an analysis of a 58 million event sample of J/{psi} decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m{sup p} at M = 1859{sub -10}{sup +3} (stat){sub -25}{sup +5} (sys) MeV/c{sup 2} and the total width is {Lambda} < 30 MeV/c{sup 2} at the 90 percent confidence level. These mass and width values are not consistent with the properties of any known particle.
119262603
Charmonium and Light Meson Spectroscopy
This talk reviews recent experimental results on selected topics in the spectroscopy of charmonia, charmonium-like states and light mesons.
118967353
Exotic in Leptonic Machines
Selected topics of exotics in leptonic machines are presented, including recent discovery of abnormal structures around the ppbar threshold and new information of the XYZ (charmonium-like) states.
119118321
A MATHEMATICAL REVIEW ON THE MULTIPLE-SOLUTION PROBLEM
The recent multiple-solution problem in extracting physics information from a fit to the experimental data in high energy physics is reviewed from a mathematical viewpoint. All these multiple solutions were previously found via a fit process, while in this paper we prove that if the sum of two coherent Breit–Wigner functions is used to fit the measured distribution, there should be two and only two nontrivial solutions, and they are related to each other by analytical formulae. For real experimental measurements in more complicated situations, we also provide a numerical method to derive the other solution from the already obtained one. The excellent consistency between the exact solution obtained this way and the fit process justifies the method. From our results it is clear that the physics interpretation should be very different depending on which solution is selected. So we suggest that all the experimental measurements with potential multiple solutions be re-analyzed to find the other solution because the result is not complete if only one solution is reported.