Charmonium and Charmonium-like States at BaBar PANIC 11 - MIT - - PowerPoint PPT Presentation

Charmonium and Charmonium-like States at BaBar PANIC 11 - MIT - July 28, 2011 Torsten Schröder Ruhr-Universität Bochum Representing the BaBar Collaboration

Outline • Introduction - Charmonia & Exotics - BaBar Experiment • Results: Charmonia Phys. Rev. D 81, - Observation of χ c2 (2P) in γγ  D D 092003 (2010) - Observation of η c (1S), η c (2S), χ cJ (1P) Phys. Rev. D 84, in γγ  K + K - π + π - π 0 , 012004 (2011) γγ  K + K - π 0 • Results: Exotics Phys. Rev. D 82, - Evidence of X(3872)  J/ ψω 011101(R) (2010) July 28, 2011 T. Schröder - PANIC 11 2

Charmonium Until 2002 • Charmonium spectrum well understood up to Mass / GeV/c 2 ψ (3770) (i.e. up to open charm threshold) • above threshold: significant width, decay mainly to open charm • Some missing states: Experiment η c (2S) h c (1P) χ cJ (2P) Potential model • No new states (Godfrey & Isgur, Phys. Rev. D32, 189) discovered between 1980 and 2002 J PC July 28, 2011 T. Schröder - PANIC 11 3

Charmonium After 2002 • Missing states observed: Mass / GeV/c 2 χ c2 (2P) - η c (2S) [Belle 2002] - h c (1P) [Cleo 2005] - χ c2 (2P) [Belle 2006] • B-factories (Belle, η c (2S) h c (1P) BaBar) contributed and also discovered Experiment numerous unexpected Potential model charmonium-like states (Godfrey & Isgur, Phys. Rev. D32, 189) - X, Y, Z - not matching J PC conventional states July 28, 2011 T. Schröder - PANIC 11 4

Exotic Charmonium-like states χ c2 (2P) QWG Report Eur. Phys. J. C71, 1534 (2011) S. Godfrey & S.Olsen, Annu. Rev. Nucl.Part. Sci. 58, 51 (2008) July 28, 2011 T. Schröder - PANIC 11 5

Exotic Charmonium-like states QWG Report Eur. Phys. J. C71, 1534 (2011) S. Godfrey & S.Olsen, Annu. Rev. Nucl.Part. Sci. 58, 51 (2008) July 28, 2011 T. Schröder - PANIC 11 6

Exotics: Interpretation Charmonium Hybrid P. Lacock et al. (UKQCD), PLB 401, 308 (1997) c c additional gluonic degree of freedom S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005) Lattice QCD: mass of lowest state ≈ 4.2 GeV/c 2 g E. Kou, O. Pene, PLB 631, 164 (2005)... J PC = 0 +- , 1 -+ , 2 +- ... possible July 28, 2011 T. Schröder - PANIC 11 7

Exotics: Interpretation Charmonium Hybrid P. Lacock et al. (UKQCD), PLB 401, 308 (1997) c c additional gluonic degree of freedom S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005) Lattice QCD: mass of lowest state ≈ 4.2 GeV/c 2 g E. Kou, O. Pene, PLB 631, 164 (2005)... J PC = 0 +- , 1 -+ , 2 +- ... possible N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004) q Molecular state q E. Braaten, T. Kusunoki, PRD 69, 074005 (2004) weakly bound pair of two mesons via π exchange c c C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 (2004) X. Liu, EPJ C54, 471 ... July 28, 2011 T. Schröder - PANIC 11 8

Exotics: Interpretation Charmonium Hybrid P. Lacock et al. (UKQCD), PLB 401, 308 (1997) c c additional gluonic degree of freedom S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005) Lattice QCD: mass of lowest state ≈ 4.2 GeV/c 2 g E. Kou, O. Pene, PLB 631, 164 (2005)... J PC = 0 +- , 1 -+ , 2 +- ... possible N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004) q Molecular state q E. Braaten, T. Kusunoki, PRD 69, 074005 (2004) weakly bound pair of two mesons via π exchange c c C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 Tetraquark (2004) c X. Liu, EPJ C54, 471 ... compact, strongly bound diquark-antidiquark pair q L. Maiani et al., PRD 71, 014028 (2005) q T.W. Chiu & T.H. Hsieh, PRD 73, 111503 (2006) c D. Ebert et al., PLB 634, 214 (2006) … July 28, 2011 T. Schröder - PANIC 11 9

Exotics: Interpretation Charmonium Hybrid P. Lacock et al. (UKQCD), PLB 401, 308 (1997) c c additional gluonic degree of freedom S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005) Lattice QCD: mass of lowest state ≈ 4.2 GeV/c 2 g E. Kou, O. Pene, PLB 631, 164 (2005)... J PC = 0 +- , 1 -+ , 2 +- ... possible N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004) q Molecular state q E. Braaten, T. Kusunoki, PRD 69, 074005 (2004) weakly bound pair of two mesons via π exchange c c C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 Tetraquark (2004) c X. Liu, EPJ C54, 471 ... compact, strongly bound diquark-antidiquark pair q L. Maiani et al., PRD 71, 014028 (2005) q T.W. Chiu & T.H. Hsieh, PRD 73, 111503 (2006) c D. Ebert et al., PLB 634, 214 (2006) … Hadrocharmonia c c within complex structure (light quarks, gluons), similar to nuclear bound c c non-zero charge & strangeness possible M.B. Voloshin, Prog. Part. Nucl. Phys. 61, 455 (2008) q c S. Dubynski et al., PLB 671, 82 (2009) ... q c g July 28, 2011 T. Schröder - PANIC 11 10

Exotics: Interpretation Charmonium Hybrid P. Lacock et al. (UKQCD), PLB 401, 308 (1997) c c additional gluonic degree of freedom S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005) Lattice QCD: mass of lowest state ≈ 4.2 GeV/c 2 g E. Kou, O. Pene, PLB 631, 164 (2005)... J PC = 0 +- , 1 -+ , 2 +- ... possible N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004) q Molecular state q E. Braaten, T. Kusunoki, PRD 69, 074005 (2004) weakly bound pair of two mesons via π exchange c c C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 Tetraquark (2004) c X. Liu, EPJ C54, 471 ... compact, strongly bound diquark-antidiquark pair q L. Maiani et al., PRD 71, 014028 (2005) q T.W. Chiu & T.H. Hsieh, PRD 73, 111503 (2006) c D. Ebert et al., PLB 634, 214 (2006) … Hadrocharmonia c c within complex structure (light quarks, gluons), similar to nuclear bound c c non-zero charge & strangeness possible M.B. Voloshin, Prog. Part. Nucl. Phys. 61, 455 (2008) q c S. Dubynski et al., PLB 671, 82 (2009) ... Conventional Meson q c g e.g. high angular momentum state C. Meng & K.T. Chao, PRD 75, 114002 (2007) Artifact W. Dunwoodie & V. Ziegler, PRL 100, 062006 (2008) e.g. threshold, cusp effects: No resonance at all O. Zhang, C. Meng & H.Q. Zheng, arXiv:0901.1553 ... July 28, 2011 T. Schröder - PANIC 11 11

The BaBar Experiment Electron-Positron Collider: PEP-II / SLAC Integrated luminosity 1999-2008: 531 fb -1 - Υ (4S): 432 fb -1 - Y(3S): 30 fb -1 - Y(2S): 14 fb -1 - Scan, Offpeak: 54 fb -1 Powerful B-Factory: 467 million B B pairs Also rich Charm source: 690 million c c events  Great environment for (charm) spectroscopy July 28, 2011 T. Schröder - PANIC 11 12

Charmonium Production at BaBar Double Charmonium Production: Color-suppressed B decays: J/ ψ or ψ (2S) and 2 nd c c state all quantum numbers c c e - c b c W - B - , B 0 γ * s q q c c e + 2-Photon Interaction: Initial State radiation: J PC =1 -- J PC =0 ±+ , 2 ±+ , 3 ++ , ... collision below CM energy e - e - γ c e - γ (*) c c γ * γ (*) e + e + c e + July 28, 2011 T. Schröder - PANIC 11 13

χ c2 (2P): Overview Radial excitations of χ cJ
 • predicted mass region 3.9 – 4.0 GeV/c 2 S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985). • no further information until 2005 Belle 2006: Z(3930) • observed in γγ  X  D D • data sample: 395 fb -1 collected at Y(4S) CMS and below • resonance parameters consistent with χ c2 (2P) PRL 96, 082003 (2006) July 28, 2011 T. Schröder - PANIC 11 14

χ c2 (2P): Overview Radial excitations of χ cJ
 • predicted mass region 3.9 – 4.0 GeV/c 2 S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985). • no further information until 2005 BABAR • confirmed observation & parameters of Z(3930) • consistent with χ c2 (2P) • observed in γγ  X  D D • Data sample: 384 fb -1 collected at Y(4S) CMS and below D 0 → K − π + D 0 → K + π − ¯ D 0 → K − π + D 0 → K + π − π 0 ¯ D 0 → K − π + D 0 → K + π − π + π − ¯ D 0 → K − π + π + π − D 0 → K + π − π 0 ¯ D + → K − π + π + D − → K + π − π − PRD 81, 092003 (2010) July 28, 2011 T. Schröder - PANIC 11 15

χ c2 (2P): Overview Radial excitations of χ cJ
 • predicted mass region 3.9 – 4.0 GeV/c 2 S. Godfrey and N. Isgur, Phys. Rev. D 32, 189 (1985). γ D • no further information until 2005 γ D BABAR • confirmed observation & parameters of Z(3930) 2-photon interaction: • consistent with χ c2 (2P) clean environment to study charmonia • observed in γγ  X  D D This analysis: • Data sample: 384 fb -1 collected at Outgoing e + , e - not detected, lost in beampipe Y(4S) CMS and below  small scattering angle D 0 → K − π + D 0 → K + π − ¯  quasi-real γ D 0 → K − π + D 0 → K + π − π 0 ¯  large missing mass m 2 miss = |p e+ +p e- -p D -p D | 2 D 0 → K − π + D 0 → K + π − π + π − ¯  small transversal momentum of resonance D 0 → K − π + π + π − D 0 → K + π − π 0 ¯  Spin-parity J P : 0 ± , 2 ± , 3 + ... D + → K − π + π + D − → K + π − π − - J=1 suppressed for quasi-real γ (Yang) - Charge conjugation C = +1 PRD 81, 092003 (2010) July 28, 2011 T. Schröder - PANIC 11 16