Recent results on non-DDbar decays of  (3770) at BES HaiLong Ma [For BES Collaboration] The IVIIth Rencontres de Moriond session devoted to QCD AND HIGH ENERGY HADRONIC INTERACTIONS (La Thuile, Italy) Mar

 R values Outline  Summary  BF[  (3770) → D 0 D 0,D + D -,DD and non-DD]  Introduction  Parameters of  (2S) and  (3770)  Search for charmless decays of  (3770)

Introduction evaluation of the electromagnetic coupling at the Z mass scale,. determination of of the muon. evaluation of understanding of  (3770) non-DD decays and others…… R(s) values are important for vacuum polarization correction, which plays an important role in the precision test of the Standard Model; R is one of the most fundamental quantities in particle physics, which counts directly the charges, the flavors and the colors of quarks involved.     

Introduction Long-standing puzzle of  (3770) production and decays  (3770) is thought to decay almost entirely to pure DDbar, but there is large discrepancy between and (Mark-III) before BES-II & CLEO-c Cross section at peak (PDG04 parameters) Simultaneously measusing both and Precisely measuring the energy dependent cross sections for both inclusive hadrons and DDbar events production simutanmeously, directly measure and Search for some exclusive non-DDbar decays BES made several fine cross section scans covering both the  (3686) and  (3770) to measure the resonance parameters, branching fractions and search for non-DD decays …

BESII  (3770) data sample of about 33 pb -1 ~17.3 pb -1 data taken at GeV ~7 pb -1 data taken at the region from GeV to GeV during Mar ~8 pb -1 data taken in the energy region from to GeV during Dec ~6.5 pb -1 of data collected at GeV ~1.0 pb -1 of data collected at GeV

E CM [GeV] σ obs had (nb) σ 0 had (nb) R Obtaining by fitting to the R values measured by BES in the range from 2.0 to 3.0 GeV PLB641(2006)145 Measurements of the R values at 3.650, and GeV

Measurements of R had, R uds(c) and R uds(c)+  (3770) in the range from to GeV efficiency ISR factor PRL 97(2006) Dec data set SourcesΔ SYS (%) Luminosity2.1 Hadron selection2.5 M.C. modeling2.0 ISR1.5 Ψ(3770) resonance parameters2.7 Total (off Ψ(3770) region) 4.0 Total (within Ψ(3770) region) 4.9 Table. Systematic uncertainties in the determination of R values

Radiative correction factor Some systematic uncertainties can be canceled out Radiative correction factor obtained based on new  (3770) resonance parameters measured by BES-II, hep/ BF[  (3770) → D 0 D 0,D + D -,DD and non-DD] PLB641(2006)145 Single tag method PLB 603(2004)130 Determination of with the measured R values at 3.650, and GeV

Line shape of the cross sections for hadron and DD-bar production  Branching fractions Simultaneously.fitting to the inclusive hadron and the DD-bar production cross sections Inclusive hadrons PRL97(2006) Mar data set

Comparison of  (3770) Resonance Parameters Mar data set PRL 97 (2006)

Comparison of  (3686) Resonance Parameters Experiment This measurement BES-II published (PLB550(2002)24) PDG2006 The measured partial width is consistent with PDG06 partial width of  (3686). PDG06 PRL97(2006) Mar data set

Precision measurements of the mass, total and leptonic widths of  (3770) with the measured R values in the range from to GeV Preliminary! hep-ex/ Dec data set Partial width

Leptonic branching fraction PRL97(2006) Preliminary! hep-ex/ (0.98+/-0.06) PRD21(1980)2716

Observed Cross Sections No obvious cross section discrepancy at the two energy points is observed. However, to extract the non-DD-bar branching fractions of  (3770) decays, one needs to consider the interference between the two amplitudes of the continuum and the resonances, and to consider the difference of ISR & vacuum polarization corrections at two energy points. Search for charmless decays of  (3770) International Journal of Modern Physics A, Vol 21 No. 27 (2006) 5416 Preliminary

 BES measured R values at the three energy points and in the energy region between and GeV Summary  BES firstly measured the branching frations for non-DDbar decays of  (3770) using two different data sample and two different methods  BES more precisely measured the parameters of the  (2S) and  (3770) resonances Thank You ！  BES searched for charmless decays of  (3770)

The R values at all energies is needed to calculate the effects of vacuum polarization on the parameters of Standard Model. [for example, and ]. A large uncertainty in this calculation arises from the uncertainties in the measured R values in the open charm threshold region (3.7 GeV to 5.0 GeV). for the evaluation of the electromagnetic coupling at the Z mass scale,. for determination of of the muon. affects the determination of the mass of Higgs boson from the measurement of indirectly. evaluation of  (3770) parameters and non-DD decays R(s) values are important for vacuum polarization correction, which plays an important role in the precision test of the Standard Model;

Measurement of R pQCD calculates the R ratioExperimentally, one measures : # of hadronic : Luminosity : Eff. events : radiative correction factor R is one of the most fundamental quantities in particle physics, which counts directly the charges, the flavors and the colors of quarks involved.

calculate R had R uds hadrons above cc-bar threshold below cc-bar threshold R had (s)=R uds(c) (s)+ΣR res,i (s), R res,i (s) is R values due to all 1 －－ resonances decay to hadrons except Ψ(3770). Definition of different R Evaluate

When scan over GeV Just before the scan experiment Mass [MeV] PDG04 BEPC BEPC energy calibration in cross section scan experiment E BEPC is the energy of BEPC set in the experiment, E true is the true energy

MC generator & simulation Full energy range ISR Generator Nch KNO φ Thrust Oblateness cosθ Sphericity Aplanarity Jet axis cosθ x η Y PtPt Density [nb/GeV] D.Zhang,G.Rong,J.C.Chen, PRD74(2006)054012

Events Recorded by BESII Cosmic-ray and beam associated background The distributions of the averaged Z of events could be estimated based on cross sections, luminosity and acceptance Radiative correction could remove the effects of high order processes from the observed cross section, and gives The events observed in the experiment

Taking the R for light hadron production to be a constant, then We obtain obtained based on PDG04  (3770) resonance parameters PLB 603(2004)130 My calculation It is consistent with  Determination of BF[  (3770) → D 0 D 0,D + D -,DD and non-DD] with the measured R values at 3.650, and GeV

Hadron efficiency vs C.M. energy Energy dependent hadron cross sections : # of hadronic : Luminosity : Eff. events Inclusive hadrons Observed cross section for hadron production [nb] The data sample used in this analysis is taken in the energy region from to GeV during Mar 2003, which cover both  (2S) and  (3770) resonance

Distributions of invariant masses of combinations at different c.m.energyies Energy dependent DDbar cross sections

Our fitted value of R uds pQCD calculated R uds Comparison of R uds with pQCD prediction

Φ π0π0 η Φ signal Φ sideband Ecm [GeV]Φ π 0 Φη around ± Search For  (3770) decay to Φπ 0 and Φη Φ π0π0 η Ecm around GeV (L=33 pb -1 ) Ecm=3.65GeV (L=6.5 pb -1 )

Ecm Φ π + π - ΦK + K - Φpp Around GeV (L=33 pb -1 ) 6.0 ± ± GeV (L=6.5 pb -1 ) ±2.6 0 K + K - π + π - K + K - pp Search For  (3770) decay to Φπ + π -, ΦK + K - and Φpp Ecm around GeV (L=33 pb -1 )Ecm=3.65GeV (L=6.5 pb -1 ) K + K - π + π - K + K - K + K - pp -

2(π + π -) η 2(π + π - ) π 0 KKπ + π - π 0 ppπ + π - π 0 ppπ 0 2(K + K - )π 0 3(π + π - ) π 0 DD-bar events have been removed. Search for  (3770) decay to multi-body final states containing π 0 or η Around 3.773GeVEcm=3.65GeV Around 3.773GeV (L=33 pb -1 ) Ecm=3.65GeV (L=6.5 pb -1 )