The  -charm BESIII SHEN Xiaoyan Institute of High Energy Physics, CAS International Review Meeting Oct. 21, 2013, IHEP, Beijing

Outline Outline Introduction Highlights from  -charm physics Management structure of BESIII Future prospects Summary 2

Standard Model (EW+QCD) Many precision tests on SM, especially EW theory, mainly in 4 exps. at LEP in CERN Higgs discovered at LHC in CERN Great success of EW theory ! QCD has been tested extensively at the high momentum transfer by lots of high precision experiments (> 10 GeV). At low energy, QCD is difficult to be tested due to its non-perturbative nature.

How does QCD work at low energy?  Do the new forms of hadrons predicted by QCD exist ?  How to calibrate QCD at low energy ? Does the physics beyond Standard Model exist?  How to test EW theory precisely in  -charm region?  Where is the new physics in  -charm sector ? Fundamental questions need to be answered What can we do at BEPC2/BESIII ?

5 BESIII detector LINAC 2004: started BEPCII upgrade, BESIII construction 2008: test run now: BESIII physics run Beijing Electron Positron Collider (BEPC) Beijing Electron Positron Collider (BEPC) beam energy: 1.0 – 2.3 GeV BEPCII/BESIII – unique facility at  -charm energy region in the word now.

Features of the BEPC Energy Region  Rich of resonances: charmonia and charmed mesons  Threshold characteristics (pairs of , D, D s, …)  Energy location of the glueballs, hybrids and multi-quark states  Energy location of the XYZ’s  Transition between smooth and resonances, perturbative and non-perturbative QCD 6 6 The Y’s are here …. PDG

How does QCD work at low energy?  Do the new forms of hadrons predicted by QCD exist ?   How to calibrate QCD at low energy ? Does the physics beyond Standard Model exist?  How to test EW theory precisely in  -charm region?   Where is the new physics in  -charm sector ? Fundamental questions need to be answered Search for the new hadrons and systematic study of the spectroscopy – a way of understanding the internal structure of hadrons.

Conventional hadrons consist of 2 or 3 quarks ： Naive Quark Model ： QCD predicts the new forms of hadrons: Multi-quark states ： Number of quarks > ＝ 4 Hybrids ： qqg ， qqqg … Glueballs ： gg ， ggg … None of them is settled after many years’ efforts. New forms of hadrons g gg g None of the new forms of hadrons is settled !

Precision measurement of CKM elements -- Test EW theory Precision measurement of CKM elements -- Test EW theory CKM matrix Three generations of quark? Unitary matrix?  5% precision  10% precision Expected precision < 2% at BESIII BESIII + B factories + LQCD Precision measurement of CKM matrix elements -- a precise test of SM model New physics beyond SM? Precision measurement of CKM matrix elements -- a precise test of SM model New physics beyond SM? 9 CKM matrix elements are fundamental SM parameters that describe the mixing of quark fields due to weak interaction. BESIII + B factories + LHCb + LQCD

 Hadron spectroscopy  search for the new forms of hadrons  meson spectroscopy  baryon spectroscopy  Study of the production and decay mechanisms of charmonium states: J/ ,  (2S),  C (1S),  C{0,1,2},  C (2S), h C ( 1 P 1 ),  (3770), etc. Calibrate QCD  Precise measurement of R values,  mass,...  Precise measurement of CKM matrix  Search for DD mixing, CP violation, etc.. Physics Topics at BESIII Physics Topics at BESIII Int. J. Mod. Phys. A, Vol. 24 (2009) 10

TOF BTOF: two layers ETOF: 48 crys. for each 11 BESIII Detector MDC R inner: 63mm ; R outer: 810mm Length: 2582 mm Layers: 43 CsI(Tl) EMC Crystals: 28 cm(15 X 0 ) Barrel: |cos  |<0.83 Endcap: 0.85 < |cos  | < 0.93 RPC MUC BMUC: 9 layers – 72 modules EMUC: 8 layers – 64 modules

BESIII Detector Performance Exps. MDC Spatial resolution MDC dE/dx resolution EMC Energy resolution CLEOc 110  m 5% % Babar 125  m 7%2.67 % Belle 130  m 5.6%2.2 % BESIII (2013) 115  m <5% (Bhabha) 2.2% Exps. TOF Time resolution CDFII100 ps Belle90 ps BESIII (2013) 68 ps (BTOF) 98 ps (ETOF) MUC: Efficiency ~ 96% BG level: < 0.04 Hz/cm 2 (B-MUC), < 0.1 Hz/cm 2 (E-MUC)

Data/Monte-Carlo Consistency For tracking efficiency, data/MC difference < 1% For particle identification efficiency, data/MC difference < 2%

BESIII Physics Results Hadron spectroscopy – Search for non-qq, non-qqq states – Meson & baryon spectroscopy Charmonium physics – Transitions and decays Charm physics – Decay constant f D – CKM matrix elements: Vcd, Vcs Precision measurement of R,  Search for new physics

BESIII Physics Results (since 2009) 15 Papers published ： –53 papers published (PRL 12, PRD 37 ， PLB 1, CPC 3 ) 2010: 4 (PRL 2, PRD 1, CPC 1) 2011: 11 (PRL 3, PRD 8) 2012: 17 (PRL 5, PRD 10, PLB 1, CPC 1) 2013: 21 (PRL 2, PRD 18, CPC 1) -- Submitted 6 (PRL 5, CPC 1) International conference talks About 50 talks at the international conferences every year. Among them, about half are the invited talks.

Highlights from  -charm Physics

Below open charm threshold All charmonium states observed. No surprising found. Above open charm threshold: many expected states not observed many unexpected discovered X(3872) XYZ(3940 ) X(3915) X(4160) Y(4008) Y(4140) Y(4260) Y(4360) X(4350) Y(4660) X(3915) X(4160) Y(4008) Y(4140) Y(4260) Y(4360) X(4350) Y(4660) Z(4430) Z(4250) Z(4050) Z(3900) Charmonium spectroscopy

Data taking at 4260 and 4360 MeV for XYZ study

BESIII: Observation of the Z c (3900) — a charged charmonium-like structure BESIII: PRL110, (2013) BESIII Significance >8  What is Z c (3900)? Couples to cc Has electric charge At least 4-quarks  DD * molecule? Tetraquark state? Cusp? Threshold effect? … Many theoretical interpretations: Submitted the paper on March 24, Already got 81 citations !

Impacts of the Z c (3900) PRL referee says: ”Since a charged charmonium-like state cannot be conventional ccbar meson, the Z(3900) may be the first indisputable example of a multi-quark meson. 81 citations PRL110, (2013)

Observation of Z c (3900) in D  D *0 Any more decay modes for Z c (3900) ? Z c (3900)  6 6  (Z c (3900)  D  D *0 )  (Z c (3900)    J/  ) J P favors 1 + Very important in understanding Z c (3900) ! arXiv: , submitted to PRL

Observation of Z  c (4020) 22 Does the charged Z c (3900)’s partner exist ? What is Z c (4020)? Couples to cc Has electric charge At least 4-quarks BESIII arXiv: , submitted to PRL

BESIII confirmed X(1835) and observed X(2120) & X(2370) BESIII confirmed X(1835) and observed X(2120) & X(2370) BESIII: Phys. Rev. Lett. 108 (2011) Glueballs can be largely produced in J/  radiative decays. First observed the resonant structures in the 2.4 GeV/c 2 region in J/  radiative decays. LQCD predicts the lowest lying 0 -+ glueball at around 2.4 GeV/c 2. What is the nature of X(2120)/X(2370) ? 0 -+ glueball ? excited  /  ’ state ? Is X(1835) the same state as pp enhancement?

Measurement of f D from D +  

Japan (1) Tokyo Univ. US (5) Univ. of Hawaii Carnegie Mellon Univ. Univ. of Minnesota Univ. of Rochester Univ. of Indiana Europe (13) Germany: Univ. of Bochum, Univ. of Giessen, GSI Univ. of Johannes Gutenberg Helmholtz Ins. In Mainz Russia: JINR Dubna; BINP Novosibirsk Italy: Univ. of Torino ， Frascati Lab, Ferrara Univ. Netherland ： KVI/Univ. of Groningen Sweden: Uppsala Univ. Turkey: Turkey Accelerator Center China(29) IHEP, CCAST, GUCAS, Shandong Univ., Univ. of Sci. and Tech. of China Zhejiang Univ., Huangshan Coll. Huazhong Normal Univ., Wuhan Univ. Zhengzhou Univ., Henan Normal Univ. Peking Univ., Tsinghua Univ., Zhongshan Univ.,Nankai Univ., Beihang Univ. Shanxi Univ., Sichuan Univ., Univ. of South China Hunan Univ., Liaoning Univ. Nanjing Univ., Nanjing Normal Univ. Guangxi Normal Univ., Guangxi Univ. Suzhou Univ., Hangzhou Normal Univ. Lanzhou Univ., Henan Sci. and Tech. Univ. Korea (1) Seoul Nat. Univ. Pakistan (2) Univ. of Punjab COMSAT CIIT ~400 members 52 institutions from 11 countries The BESIII Collaboration 25 ~180 members from IHEP

BESIII Management Structure Spokespersons (3, 3 years term) EB(~9) Run coordinator Software and Computing coordinator Physics coordinators Speakers bureau Publication committee Shift committee Membership committee IB(~51) Convener-1 Convener-2 ……… Similar to other International Collaborations

Rules and policies BESIII Collaboration Governance Rules BESIII membership rules Publication Policy Responsibilities of the Speakers Bureau …….. Responsibilities of the Speakers Bureau Data Taking Data taking proposals presented and discussed at CM, decision made by EB and collaboration Adjust the data taking plans accordingly taking into account the importance of the physics, the competitions from other exps. Run coordinator, weekly run coordinators, chief shifters, shifters, on-call people, …. to ensure the high quality data.

IHEP Contribution MDC & electronics EMC & electronics BTOF ETOF & electronics MUC MUC electronics Trigger & DAQ IHEP USTCIHEPUSTCIHEP MDCEMCTOFMUCPhysics tools IHEP+SDUIHEP PKU+IHEPIHEP+USTC BESIII software BESIII software The design, construction & operation of BESIII The design, construction & operation of BESIII BESIII papers BESIII papers TotalIHEP IHEP supervisors + univ. students Universities

IHEP Manpower Currently, 57 faculties (16 profs. ) and 42 Students & post-docs for the maintenance, operation, upgrade of BESIII, and for the software and physics analysis.

Leading scientists WANG Yifang (Spokesperson from 2005 to Nov. 2011) SHEN Xiaoyan (Spokesperson from Dec. 2011) LOU Xinchou (EB member, IHEP IB) ZHU Kejun, HE Kanglin (Run coordinators) YUAN Changzheng (Physics coordinator) LI Weidong (Software coordinator, EB member) LI Haibo, JIN Shan (Were physics coordinators) DONG Liaoyuan, ZHANG JIngzhi, FANG Shuangshi, MO Xiaohu, LIU Huaimin, …… (conveners)

BESIII data taking status & plan Previous data BESIII present & near future Goal J/  BESII: 58M1.2 B 20* BESII10 B ’’ CLEO: 28 M0.5 B 20* CLEOc3B ”” CLEO: 0.8/fb2.9/fb 3.5*CLEOc10/fb  4040)/  4170)/  4260) …. CLEO:  4160) 2011:  4040) 2013 ： /fb R scanBESII Prospects of BESIII

In physics run, R scan above 3.8 GeV. The goal: reach the precision of ~2% for R values. More results on XYZ particles will come  understand the nature of XYZ Search for glueballs, hybrids,… with huge J/  data. Precision measurement of CKM elements  mass Expected to have an error of 0.1MeV. Prospects of BESIII fDfD

Summary Observed Z c (3900), Z c (4020) at BESIII, opened a new window  big impact. More results on XYZ particles will come  understand the nature of XYZ Produced many important results on charmonium physics, hadron spectroscopy, …. BESIII will run another 7-10 years Upgrade of BESIII on going – MRPC for ETOF – New inner drift chamber – CGEM for drift chamber More data will come, more physics output Keep the leading role in  -charm physics in these years.

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Backup slides

36 Matters are made of leptons and quarks: Interactions are mediated by: photons — electromagnetic W ± and Z — weak gluons — strong  QCD Origin of masses Higgs (Discovered at LHC in 2012) Electroweak theory (EW) Standard Model (SM)

37 Pure leptonic decays All quantities are well measured except f D. Use world average |V cd | to extract f D Compare f D with LQCD for the validation of LQCD

Preliminary study of D +   at BESIII 9 singly D - tag modes

The error is still statistical dominated.

Comparison of f D with theories f D (MeV)

Z c (4020)’s other decay mode ? Observation of Z c (4025) in D*  D *0 arXiv: , submitted to PRL

Standard Model and BES Physics Three generations of quarks and leptons Interactions – Electromagnetic interaction – Weak interaction – Strong interaction BES  - charm Physics ｝ EW theory QCD theory

Y.B. Yang, et al, Phys. Rev. Lett. 111, (2013) The widths of J/  radiatively decay to glueballs are calculated directly in lattice QCD. This result can be compared to the production rates of scalar mesons f0(1710), f0(1500) Support f 0 (1710) to be dominantly a scalar glueball. Scalar glueball production in J/  radiative decays from LQCD Scalar glueball production in J/  radiative decays from LQCD

Tensor glueball production in J/  radiative decays from LQCD Tensor glueball production in J/  radiative decays from LQCD The tensor glueball production rate in J/  radiative decay With the largest J/psi events sample, the LQCD results can provide useful information for BESIII to identify the tensor glueballs. L. Gui, et al, Phys. Rev. Lett. 110 (2013)

Paper submission procedures Talk at the group meeting, get approval by the group and group convener, get the analysis memo ready. Talk at the phys. & software meeting, get approval Physics coordinators assign 3 internal referees to review the analysis, memo  draft  be approved Collaboration wide review Spokespersons’ approval The time from the submission to the journal to finally being accepted for publication is short.