Highlights from BESIII Hai-Bo Li for BESIII Collaboration Institute of High Energy Physics Beijing, China XIV International Conference on Hadron Spectroscopy June 13 – 17, 2011 Künstlerhaus, in München , Germany June 15, 2011 Hai-Bo Li (IHEP) 1
Outline • Status of BEPCII/BESIII • Results from Charmonium data samples • 2010-11: First open charm runs • Charm Physics: advantage near threshold • Conclusion June 15, 2011 Hai-Bo Li (IHEP) 2
BESIII – physics using “charm” Charmonium physics: - Spectroscopy - transitions and decays Light hadron physics: - meson & baryon spectroscopy - glueball & hybrid - two-photon physics - e.m. form factors of nucleon Charm physics: - (semi)leptonic + hadronic decays - decay constant, form factors - CKM matrix: Vcd, Vcs - D 0 -D 0 bar mixing and CP violation - rare/forbidden decays Tau physics: - Tau decays near threshold - tau mass scan …and many more. June 15, 2011 Hai-Bo Li (IHEP) 3
BESIII final goal J/ ψ − 10 10 ψ (2S) − 3 × 10 9 ψ (3770) − 6 × 10 8 Higher ψ ’s − 10 7 In decays: (1S)-10 8 η c 10 8 χ cJ − h c 10 7 − ( ψ (2S) → h c π 0 ) 10 η / η ’ samples 8 Rare η / η ’ decays Comprehensive study of charmonium decays charm and charmonium spectroscopy June 15, 2011 Hai-Bo Li (IHEP) 4
Satellite view of BEPCII /BESIII LINAC South 2004: start BEPCII construction 2008: test run of BEPCII BESIII 2009-now: BECPII/BESIII detector data taking June 15, 2011 Hai-Bo Li (IHEP) 5
BEPCII storage rings Beam energy: 1.0-2.3 GeV Design Luminosity: 1 × 10 33 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 × 10 -4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A Circumference ： 237m June 15, 2011 Hai-Bo Li (IHEP) 6
June 15, 2011 Hai-Bo Li (IHEP) 7
Data samples • So far BESIII has collected : – 2009: 225 Million J/ ψ – 2009: 106 Million ψ ’ – 2010-11: 2.9 fb − 1 ψ (3770) (3.5 × CLEO-c 0.818fb − 1 ) - May 2011: 0.5fb − 1 @4010 MeV (one month) for Ds and XYZ spectroscopy • BESIII will also collect: – more J/ ψ , ψ ’, ψ (3770) – data at higher energies （ for XYZ searches, R scan and Ds physics ） June 15, 2011 Hai-Bo Li (IHEP) 8
since startup luminosity Note that luminosity is lower at J/ ψ , and machine is optimal near ψ (3770) Integrated luminosity: Jan. 2009– June 3 2011 about 4.0 fb -1 @ different energies Note increase in slopes! 2011: ψ (3770) & ψ (4040) for Ds 2010: ψ (3770) 2009: ψ′ & J/ ψ June 15, 2011 Hai-Bo Li (IHEP) 9
Recent ψ (3770) running Reference point: L = 0.5 × 10 33 /cm 2 /s (maximum 0.65 × 10 33 ) theoretically lumi: 43 pb -1 /day But, filling beam, HV ramp, lumi. decay and down time loss 40% Best week : 160.8 pb -1 Best day : 29 pb -1 Beam current: 700 mA × 700mA Peak luminosity Luminosity curve (decay curve) 0.6 × 10 33 /cm 2 /s Best day on April 7 2011 June 15, 2011 Hai-Bo Li (IHEP) 10
6 groups from Germany BESIII Collaboration Helmholtz Institute Mainz 11 11 Johannes Gutenberg-University Mainz Turkey: Turkish accelerator center 29 29 >300 physicists 49 institutions from 10 countries June 15, 2011 Hai-Bo Li (IHEP) 11
Released results of BESIII • Charmonium Spectroscopy and Transitions – Properties of the h c (PRL 104, 132002 (2010)) – ψ ′ → γγ J/ ψ (submitted soon ) 10 papers published • Charmonium Decays – π 0 π 0 , ηη (PRD 81, 052005 (2010)) χ cJ → – → γρ , γω , γφ (PRD83,112005(2011)) χ cJ – → ωω , φφ , ωφ (submitted to PRL) χ cJ – ψ ′ → γ π 0 , γη , γη′ (PRL 105, 261801 (2010)) – 4 π 0 (PRD 83, 012006 (2011) ) χ cJ → – Observation of χ cJ ppK + K ‐ (accepted by PRD) → • Light Quark States – a 0 (980) − f 0 (980) mixing (PRD 83, 032003 (2011) ) – matrix element (PRD 83, 012003 (2011)) η′→η π + π − – X(1860) in J/ ψ → γ (pp) (Chinese Physics C 34, 4 (2010)) – X(1835) in J/ ψ → γ ( η′ π + π − ) (PRL 106, 072002 (2011)) – X(1870) in J/ ψ → ω ( η π + π − ) (submitted soon) More than 20 analyses are under internal review! June 15, 2011 Hai-Bo Li (IHEP) 12
Property of h c (1p1) June 15, 2011 Hai-Bo Li (IHEP) 13
Observation of h c in inclusive reaction June 15, 2011 Hai-Bo Li (IHEP) 14
h c (1P1) in ψ′→ π 0 h c , h c � γη c, η c � X i (exclusive) ψ′→ π 0 h C , h C , →γη C is reconstructed η C exclusively with 16 decay modes Black from PDG2010, blue from estimation of ψ′→γη C For detail see Quarkonia session: Liangliang Wang’s talk on June 13 June 15, 2011 Hai-Bo Li (IHEP) 15
recoil mass in h c � γη c, η c � X i π 0 Sum of π 0 recoil mass Simultaneous fit to π 0 recoiling mass Consistent with BESIII inclusive in 106M ψ′ sample (preliminary results): results PRL104,132002(2010) M(h c ) =3525.31 ± 0.11 (stat) ± 0.15 (sys) MeV/c 2 CLEOc exlusive results Γ (h c ) = 0.70 ± 0.28 (stat) ± 0.25 (sys) MeV M(h c )=3525.21 ± 0.27 ± 0.14 MeV/c 2 N = 832 ± 35 N = 136 ± 14 PRL101, 182003(2008) χ 2 /d.o.f. = 32/46 June 15, 2011 Hai-Bo Li (IHEP) 16
lineshape from ψ′→ π 0 h C , h C η C →γη C Background Sum of 16 of subtracted decay modes η C The η C lineshape is not distorted in the h C →γη C Detail analysis of η c parameters is ongoing! Symmetric lineshape Asymmetric in γγ production lineshape in ψ decay June 15, 2011 Hai-Bo Li (IHEP) 17
resonance parameters from ψ′→γη C η C BESIII BESIII BESIII preliminary preliminary preliminary ππ η KsK π KK π 0 BESIII BESIII BESIII preliminary preliminary preliminary 3( ππ ) KsK3 π 2K2 ππ 0 Simultaneous fit with r-BW by considering the interference between η c and non- η c decays , as well as the energy dependence of phase space: φ : relative phase between η c decay mass: 2984.4 ± 0.5 stat ± 0.6 sys MeV/ c 2 and non-resonant component under the signal region by assuming all width: 30.5 ± 1.0 stat ± 0.9 sys MeV non- η c is 0 − + , and an universal phase φ : 2.35 ± 0.05 stat ± 0.04 sys rad for different modes is used. June 15, 2011 Hai-Bo Li (IHEP) 18
Comparison of the mass and width for η c The world average in PDG2010 was using earlier results BESIII results include both stat. and syst. errors, which is the most precision measurement, the interference between decay and non-resonance is important. η c For detail see Quarkonia session on June 13: Liangliang Wang June 15, 2011 Hai-Bo Li (IHEP) 19
Observation of η c (2S) in ψ′→γη c (2S), η c (2S) → K s K π With 106M ψ′ events: BESIII preliminary M( η c (2S)) = (3638.5 ± 2.3 ± 1.0) MeV/c 2 N( η c (2S)) = 50.6 ± 9.7 Statistical significance larger than 6.0 σ! Br( ψ ’ � γη c (2S) � γ KsK π ) =(2.98 ± 0.57 stat ± 0.48 sys ) × 10 -6 + Br( η c (2S) � KK π )=(1.9 ± 0.4 ± 1.1)% From BABAR(PRD78,012006) Br( ψ ’ � γη c (2S)) =(4.7 ± 0.9 stat ± 3.0 sys ) × 10 -4 M1 transition CLEO-c: <7.6 × 10 − 4 PRD81,052002(2010) Potential model: (0.1 − 6.2) × 10 − 4 Γ ( η c (2S)) fixed to 12MeV (world average) PRL89,162002(2002) For detail see Quarkonia session on June 13: Liangliang Wang June 15, 2011 Hai-Bo Li (IHEP) 20
Measurement of J/ ψ→ pp, nn With 2.2 million J/ ψ at BESIII, with help of EMC, we can access neutron-anti-neutron final states June 15, 2011 Hai-Bo Li (IHEP) 21
Preliminary results: J/ ψ→ pp, nn Anti-neutron identifications: BESIII preliminary BESIII preliminary BESIII preliminary nn pn π − Angle between n and recoiling direction of n EMC energy deposit: 0.6<E(anti-neutron)<2.0 GeV Comparison for anti-neutron in J/ ψ→ nn and pn π − Angle between n and recoiling direction of n Br(J/ ψ � pp) = (2.112 ± 0.004 ± 0.027) ✕ 10 -3 Br(J/ ψ � pp) ~ Br(J/ ψ � nn) PDG: Br(J/ ψ � pp) = (2.17 ± 0.07) ✕ 10 -3 suggests a large angle (~90 0 ) Br(J/ ψ � nn) = (2.07 ± 0.01 ± 0.14) ✕ 10 -3 between strong and EM PDG: Br(J/ ψ � nn) = (2.2 ± 0.4) ✕ 10 -3 amplitudes! June 15, 2011 Hai-Bo Li (IHEP) 22
Preliminary results: J/ ψ→ pp, nn Anti-neutron identifications: BESIII preliminary BESIII preliminary BESIII preliminary nn pn π − Angle between n and recoiling direction of n EMC energy deposit: 0.6<E(anti-neutron)<2.0 GeV This technique tells us that we Comparison for anti-neutron in J/ ψ→ nn can measure neutron-antineutron and pn π − Angle between n and recoiling direction of n cross section between 2.0-4.0 GeV by using scan data, which is important. Br(J/ ψ � pp) = (2.112 ± 0.004 ± 0.027) ✕ 10 -3 See MAGGIORA, Marco in Quarkonia session Br(J/ ψ � pp) ~ Br(J/ ψ � nn) PDG: Br(J/ ψ � pp) = (2.17 ± 0.07) ✕ 10 -3 on June 13 suggests a large angle (~90 0 ) Br(J/ ψ � nn) = (2.07 ± 0.01 ± 0.14) ✕ 10 -3 between strong and EM PDG: Br(J/ ψ � nn) = (2.2 ± 0.4) ✕ 10 -3 amplitudes! June 15, 2011 Hai-Bo Li (IHEP) 23
Evidence for ψ′ decays into γ π and γη PRL105, 261801(2010) We are measuring BRs at 10 -6 June 15, 2011 Hai-Bo Li (IHEP) 24
Some surprises PRL105, 261801(2010) Q. Zhao, PLB697(2011)52 June 15, 2011 Hai-Bo Li (IHEP) 25
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