Recent Results on (3770) Physics at BES Ming-gang Zhao (For BES Collaboration) The 44 th Rencontres de Moriond, QCD and High Energy Interactions March 14-21, 2009, La Thuile, Italy
Introduction Summary Measurements about (3770) non-DD Outline Anomalous line-shape of e+e- hadrons in energy region from 3.65 to 3.87 GeV Measurement of D+D- (s)/ D0D0 (s)
Introduction Only exist one resonance: (3770) Long standing (3770) decay puzzle Knowledge about 3.70~3.87 GeV region [before BES-II and CLEO-c results] Theory prediction: nearly 100% DD decay Experiment measurement: unsaturation (nearly 40%) of (3770) production and decay
Introduction about 17.3 pb -1 data taken at GeV about 7 pb -1 data taken from GeV to GeV [pb -1 ] World (3770) Samples about 8 pb -1 data taken from to GeV about 1 pb -1 data taken at GeV BESII (3770) data sample Data Samples about 6.5 pb -1 data taken at GeV
Several different methods and data samples , and systematical studies on B[ (3770)→non-DD]. All first time measurements. Measurements about (3770) non-DD PDG 2008 PRD76, PLB659, 74PRL97, PLB641, 145
Anomalous line-shape high-energy sidelow-energy side One simple (3770) resonance hypothesis is quite questionable to fit the current data. initial state radiation DD production threshold the energy dependence of the D D scattering amplitudes due to the Blatt-Weisskopt barrier high energy slope steep than low energy slope low energy slope steep than high energy slope Two data sets taken in March and December 2003
Anomalous line-shape Solution 1: two amplitudes, no interference Solution 2: two amplitudes, complete interference Comparison: one (3770) amplitude hypothesis Solution 3: (3770) amplitude + G(3900), interference The expected cross section for e + e - hadrons: Rs(3770) means the full structure around GeV, we use one or two pure P wave Breit-Wigner amplitude(s) with energy dependent to express Babar PRD76 (2007) (R); Belle PRD77 (2008) (R) PRL101 (2008)
Anomalous line-shape Solution 1: two amplitudes, no interference Circles with error bars in black are the observed cross section; Red line: fitted values of cross section; Green line: the fit with one (3770) hypothesis; Circles with error bars in red are the measured net cross sections after subtracting J/ and continuum contribution. The blue line shows the fits PRL101 (2008)
Anomalous line-shape Circles with error bars in black are the observed cross section; Red line: fitted values of cross section; Green line: the fit with one (3770) hypothesis; Circles with error bars in red are the measured net cross sections after subtracting J/ and continuum contribution. The blue line shows the fits Solution 2: two amplitudes, complete interference PRL101 (2008)
Anomalous line-shape Solution 3: (3770) amplitude + G(3900), interference Red line: Solution 3 Blue line: one (3770) Yellow line: Solution 1 Green line: Solution 2 The ratio of the residual between the observed cross section and the fitted value for one (3770) amplitude to the error of the observed cross section PRL101 (2008)
Anomalous line-shape 2. Significance of the interference between the two amplitudes is 3.6 1. Significance of the two amplitudes is more than 7 Solution with two amplitudes +G(3900) gives almost the same results with Solution 2 The hypothesis of (3770) amplitude +G(3900) and interference does not significantly improve the fit from the one (3770) amplitude hypothesis PRL101 (2008)
Numbers of events and Detection efficiencies Measurement of D+D- (s)/ D0D0 (s) PLB668 (2008) 263
DD [nb] Measurement of D+D- (s)/ D0D0 (s) D+D- (s)/ D0D0 (s) PLB668 (2008) 263 Cross section for DD production
Summary Anomalous lineshape of e+e- hadrons (s) in energy region from 3.65 to 3.87 GeV Measurement of D+D- (s)/ D0D0 (s) in energy region from 3.74 to 3.80 GeV Systematic study about B[ (3770) non-DD]
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