Recent Results on (3770) Physics at BES
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Transcript of Recent Results on (3770) Physics at BES
Recent Results on (3770) Physics at BES
Ming-gang Zhao
(For BES Collaboration)
The 44th 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 3.773 GeV about 7 pb-1 data taken from 3.768 GeV to 3.778 GeV
0
100
200
300
400
500
600
700
800
900
MARK-I DELCO MARK-II MARK-III BES-II CLEO-c
[pb-1]
World (3770) Samples
about 8 pb-1 data taken from 3.665 to 3.878 GeV
about 1 pb-1 data taken at 3.665 GeV
BESII (3770) data sample
Data Samples
about 6.5 pb-1 data taken at 3.650 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, 122002 PLB659, 74PRL97, 121801PLB641, 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
)(Eσ)(Eσ)(Eσ)(Eσ)(Eσ cmCTMhadcm
expψ(3686)cm
expJ/ψcm
expRs(3770)cm
exphad
2cm2
2cm1cm
expRs(3770) )(EA)(EA)(Eσ
2cm2cm1cm
expRs(3770) )(EA)(EA)(Eσ ie
The expected cross section for e + e - hadrons:
Rs(3770) means the full structure around 3.773 GeV, we use one or two pure P wave Breit-Wigner amplitude(s) with energy dependent to express
Babar PRD76 (2007) 111105(R); Belle PRD77 (2008) 011103(R)
PRL101 (2008) 102004
])M(EiΓ)M(E
Γ12π)(E[A
jcmtotj
2j
2cm
hadj
eej
cmj
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) 102004
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) 102004
Anomalous line-shape
Solution 3: (3770) amplitude + G(3900), interference
Red line: Solution 3Blue line: one (3770) Yellow line: Solution 1Green line: Solution 2The 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) 102004
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
3.
4. 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) 102004
Numbers of events and Detection efficiencies
Measurement of D+D-(s)/D0D0(s)PLB668 (2008) 263
DD [n
b]
Measurement of D+D-(s)/D0D0(s)D+
D-(s
)/D0
D0(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]
Thank You !