中國(guó)高能物理學(xué)會(huì)第十屆全國(guó)粒子物理學(xué)術(shù)會(huì)議,南京

1、中國(guó)高能物理學(xué)會(huì)第十屆全國(guó)粒子物理學(xué)術(shù)會(huì)議中國(guó)高能物理學(xué)會(huì)第十屆全國(guó)粒子物理學(xué)術(shù)會(huì)議, 南京南京 Observation of X(1835) in Observation of X(1835) in J房雙世房雙世“晨光杯晨光杯”論文報(bào)論文報(bào)告告Outline Introduction Event Selection Background Study Results Summary and Discussion A narrow enhancement is observed in . Assuming that the system is in an S-wave resulted in

2、a resonance mass of MeV and a total width of MeV. ppJpp5325101859m30M=1859 MeV/c2 30 MeV/c2 (90% CL) +3 +5 10 25M(pp)-2mp (GeV)00.10.20.3IntroductionIntroductionppJ It can be interpreted as a ppbar bound state. In such a case, it is desirable to observe such a state in other decay modes. Many possib

3、le decay modes suggested in C. S. Cao and S.L. Zhu Commun. Theory. Phys. 42, 844(2004) C. J. Ding and M. L. Yan, Phys. Rev. C72(2005)J One possible decay modes, never studied before at BES easy to tag using Charged tracks4 good charged tracks with |cos |0.8 in MDC;The total charge is required to be

4、0;PID: at least three of them are identified as pions with TOF and dE/Dx ;Photon selection Energy deposited in BSC greater than 60 MeVIsolated from charged tracks by more than 5oN =3 forN =2 for Event Selection)(J)(J used to improve the mass resolution Event Selection for )(J824CGeVMM05. 0|1525CMGeV

5、MM015. 0| Analysis of)(JX(1835) Event Selection for )(J224KKC824C GeVMGeVmMGeVM82. 072. 005. 0|22. 0GeVMM025. 0|0 Analysis of )(JX(1835) mass-sideband events Main background, 60M decays by LUND model Check efficiency curve phase space Background Study0JJJBkg. study for )(JLUND MC)(0J sidebandsdatada

6、ta Bkg. Study for )(JPhase space eventsEfficiency curveMCBkg. Study for )(JLUND MC)(0J sidebandsdatadata)(J Bkg. Study for Efficiency curvePhase space eventsMC)(JObservation of X(1835) in The sum + - mass spectrum for decaying into + - and JJ Mass spectrum fitting 2668obsNMeVm1 . 84 .1827MeV5 .342 .

7、54 410)7 . 08 . 1 ()()(XBXJB5.1 The + - mass spectrum for )(J Mass spectrum fitting 43193obsNMeVm9 . 73 .1836MeV1 .233 .70 410)5 . 03 . 2()()(XBXJB6.0 The + - mass spectrum for )(J Mass spectrum fitting 54264obsNMeVm7 . 21 . 67 .1833MeV7 . 73 .207 .67 410)4 . 04 . 02 . 2()()(XBXJB7.7 The sum + - mas

8、s spectrum for decayinginto + - and Mass and width from m=1827.4 8.1MeV/c2 , =54.2 34.5MeV/c2 Mass and width from m=1836.3 7.9MeV/c2 , =70.3 23.1MeV/c2The sum of mass spectrum for two decay modes m=1833.7 6.1 2.7MeV/c2 , =67.7 20.3 7.7MeV/c2)(J)(J The sum of mass spectrum for two decay modes )(J410)

9、7 . 08 . 1 ()()(XBXJB)(J410)4 . 04 . 02 . 2()()(XBXJB410)5 . 03 . 2()()(XBXJBqThe mass, width and branching fractions obtained from two different decay modes are consistent with each other.Results of mass spectrum fittingPaper published inPhys. Rev. Lett. 95,262001(2005)(Received 11 August 2005; pub

10、lished 28 December 2005) SPIRES-HEP search(2008-04-01) 39 times cited 首次在以我國(guó)科學(xué)家為主首次在以我國(guó)科學(xué)家為主進(jìn)行的北京譜儀實(shí)驗(yàn)中發(fā)進(jìn)行的北京譜儀實(shí)驗(yàn)中發(fā)現(xiàn)新粒子。現(xiàn)新粒子。國(guó)際權(quán)威粒國(guó)際權(quán)威粒子數(shù)據(jù)手冊(cè)子數(shù)據(jù)手冊(cè)PDG2006首首次收錄次收錄以中國(guó)科學(xué)家為主以中國(guó)科學(xué)家為主發(fā)現(xiàn)的新粒子發(fā)現(xiàn)的新粒子X(1835)等。等。強(qiáng)烈反響和廣泛的認(rèn)同強(qiáng)烈反響和廣泛的認(rèn)同 (I) 粒子數(shù)據(jù)手冊(cè)在粒子數(shù)據(jù)手冊(cè)在2006年版的年版的“非常規(guī)介子非常規(guī)介子”綜綜合評(píng)述部分，合評(píng)述部分，因因BES實(shí)驗(yàn)實(shí)驗(yàn)的新發(fā)現(xiàn)而首次加入有關(guān)的新發(fā)現(xiàn)而首次

11、加入有關(guān)“質(zhì)子反質(zhì)子束縛態(tài)質(zhì)子反質(zhì)子束縛態(tài)”的評(píng)述。的評(píng)述。強(qiáng)烈反響和廣泛的認(rèn)同強(qiáng)烈反響和廣泛的認(rèn)同 (II) 在國(guó)內(nèi)，在國(guó)內(nèi)，“北京電子對(duì)撞機(jī)上發(fā)現(xiàn)北京電子對(duì)撞機(jī)上發(fā)現(xiàn)X1835新粒子新粒子”被評(píng)為被評(píng)為 “2006年度中國(guó)基礎(chǔ)研究十大新聞年度中國(guó)基礎(chǔ)研究十大新聞”第一名第一名 “2006年度國(guó)內(nèi)十大科技新聞年度國(guó)內(nèi)十大科技新聞”第二名。第二名。 Summary and DiscussionqA new resonance X(1835) observed in qThe mass, width and branching fractions obtained from two differ

12、ent decay modes are consistent with each other. J X(1835) could be the same structure as ppbar mass threshold enhancement. It could be a ppbar bound state since it dominantly decays to ppbar when its mass is above ppbar mass threshold. Its spin-parity should be 0-+: this would be an important test.

13、PDG2006 takes it as a possible ppbar bound state.Fit to J/ pp including FSIInclude FSI curve from A.Sirbirtsev et al.(hep-ph/ 0411386) in the fit (I=0)M = 1830.6 6.7 MeV = 0 93 MeVpppmM2In good agreement with X(1835)Summary and Discussionq Other interpretations are not excluded. q Glueball? N. Koche

14、lev, D. P. Min Phys. Lett. B633:283(2006); B.A. Li, Phys. Rev. D74:034019(2006); C. F. Qiao Phys. Lett. B642:53(2006) q radial excitation ? T. Huang S. L. Zhu Phys. Rev D73:014023(2006)Determination of its IGJPC helps us to understand this resonance Confirmation of X(1835) in other decay modes needed With 100 times high quality data, may BESIII issue a new “birth certificate” for X(1835) soon ! Summary and Discussion謝謝 謝謝Back u