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 Schrder Ruhr-Universitt Bochum Representing the BaBar Collaboration Outline Introduction - Charmonia & Exotics - BaBar Experiment Results:
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092003 (2010)
012004 (2011)
011101(R) (2010)
Until 2002
well understood up to ψ(3770) (i.e. up to
significant width, decay mainly to open charm
ηc(2S) hc(1P) χcJ(2P)
discovered between 1980 and 2002
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Mass / GeV/c2 JPC
Experiment Potential model (Godfrey & Isgur,
After 2002
BaBar) contributed and also discovered numerous unexpected charmonium-like states
conventional states
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Mass / GeV/c2 JPC
Experiment Potential model (Godfrey & Isgur,
χc2(2P) hc(1P) ηc(2S)
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QWG Report
1534 (2011)
χc2(2P)
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QWG Report
1534 (2011)
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c c g
S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005)
Charmonium Hybrid additional gluonic degree of freedom Lattice QCD: mass of lowest state ≈ 4.2 GeV/c2 JPC = 0+-, 1-+, 2+-... possible
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c c g c q c q
S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005)
Charmonium Hybrid additional gluonic degree of freedom Lattice QCD: mass of lowest state ≈ 4.2 GeV/c2 JPC = 0+-, 1-+, 2+-... possible Molecular state weakly bound pair of two mesons via π exchange
N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004)
074005 (2004) C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 (2004)
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c c g c q c q q c c q
T.W. Chiu & T.H. Hsieh, PRD 73, 111503 (2006)
S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005)
Charmonium Hybrid additional gluonic degree of freedom Lattice QCD: mass of lowest state ≈ 4.2 GeV/c2 JPC = 0+-, 1-+, 2+-... possible Molecular state weakly bound pair of two mesons via π exchange Tetraquark compact, strongly bound diquark-antidiquark pair
N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004)
074005 (2004) C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 (2004)
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c c g c q c q q c c q
T.W. Chiu & T.H. Hsieh, PRD 73, 111503 (2006)
S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005)
M.B. Voloshin, Prog. Part. Nucl. Phys. 61, 455 (2008)
Charmonium Hybrid additional gluonic degree of freedom Lattice QCD: mass of lowest state ≈ 4.2 GeV/c2 JPC = 0+-, 1-+, 2+-... possible Molecular state weakly bound pair of two mesons via π exchange Tetraquark compact, strongly bound diquark-antidiquark pair Hadrocharmonia cc within complex structure (light quarks, gluons), similar to nuclear bound cc non-zero charge & strangeness possible q c c q g
N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004)
074005 (2004) C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 (2004)
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c c g c q c q q c c q
N.A. Tornqvist, PLB 590, 209 (2004) E.S. Swanson, PLB 598, 197 (2004)
074005 (2004) C.Y. Wong, PRC 69, 055202 (2004) M.B. Voloshin, PLB 579, 316 (2004) F.E. Close & P.R. Page, PLB 578, 119 (2004)
T.W. Chiu & T.H. Hsieh, PRD 73, 111503 (2006)
S.L. Zhu, PLB 625, 212 (2005) F.E. Close, P.R. Page, PLB 628, 215 (2005)
Artifact e.g. threshold, cusp effects: No resonance at all
M.B. Voloshin, Prog. Part. Nucl. Phys. 61, 455 (2008)
Charmonium Hybrid additional gluonic degree of freedom Lattice QCD: mass of lowest state ≈ 4.2 GeV/c2 JPC = 0+-, 1-+, 2+-... possible Molecular state weakly bound pair of two mesons via π exchange Tetraquark compact, strongly bound diquark-antidiquark pair Hadrocharmonia cc within complex structure (light quarks, gluons), similar to nuclear bound cc non-zero charge & strangeness possible Conventional Meson e.g. high angular momentum state q c c q g
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Electron-Positron Collider: PEP-II / SLAC Integrated luminosity 1999-2008: 531 fb-1
Powerful B-Factory: 467 million BB pairs Also rich Charm source: 690 million cc events Great environment for (charm) spectroscopy
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e- e+ cc cc e- e+ c c γ γ* γ* e- e- e+ e+ γ(*) γ(*) c c
2-Photon Interaction: JPC=0±+, 2±+, 3++, ... Double Charmonium Production: J/ψ or ψ(2S) and 2nd cc state Initial State radiation: JPC=1-- collision below CM energy Color-suppressed B decays: all quantum numbers
c c b W- q q s B-, B0
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Radial excitations of χcJ
Belle 2006: Z(3930)
Y(4S) CMS and below
PRL 96, 082003 (2006)
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Radial excitations of χcJ
BABAR
parameters of Z(3930)
Y(4S) CMS and below
D0 → K−π+ ¯ D0 → K+π− D0 → K−π+ ¯ D0 → K+π−π0 D0 → K−π+ ¯ D0 → K+π−π+π− D0 → K−π+π+π− ¯ D0 → K+π−π0 D+ → K−π+π+ D− → K+π−π−
PRD 81, 092003 (2010)
Radial excitations of χcJ
BABAR
parameters of Z(3930)
Y(4S) CMS and below
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PRD 81, 092003 (2010) D D 2-photon interaction: clean environment to study charmonia This analysis: Outgoing e+, e- not detected, lost in beampipe small scattering angle quasi-real γ large missing mass m2
miss = |pe++pe--pD-pD|2
small transversal momentum of resonance Spin-parity JP: 0±, 2±, 3+...
γ γ
D0 → K−π+ ¯ D0 → K+π− D0 → K−π+ ¯ D0 → K+π−π0 D0 → K−π+ ¯ D0 → K+π−π+π− D0 → K−π+π+π− ¯ D0 → K+π−π0 D+ → K−π+π+ D− → K+π−π−
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∝
t(m − mt)αe[−β(m−mt)]
Signal: convolution of relativistic Breit-Wigner with detector resolution parameterization Background model: Belle Mass: 3929 ± 5 ± 2 MeV/c2 Width: 29 ± 10 ± 2 MeV Γγγ×BF = 0.18 ± 0.05 ± 0.03 keV NSignal = 76 ± 17 Significance 5.8σ PRD 81, 092003 (2010)
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Entries in signal region (from fit to data; m, Γ fixed) Data efficiency corrected, ε(cosθ) D θ DD Lab momentum D Spin 2, Helicity 2 (Helicity 0 contribution largely suppressed) Spin 0 Flat distribution
DD rest frame
Spin 2 most likely, Production, Decay JPC=2++ States with higher J unlikely Spin, Mass: χc2(2P) [PDG 2010]
PRD 81, 092003 (2010)
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ηc(1S) [Charmonium ground state]
production process
Γ ≈ 30 MeV in B decays, 2-photon int. ηc(1S) mass ηc(1S) width PDG 2010
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ηc(2S)
but no significant signal
double charmonium production
between charmonium models ηc(2S) mass PDG 2010
July 28, 2011
BABAR Data sample: 519 fb-1 collected at Y(2S,3S,4S) CMS in
γγ → K0
SK+π−
)
2
) (GeV/c
! !
"
"
K
S
m(K 2.6 2.8 3 3.2 3.4 3.6 3.8 4 )
2
Events / ( 0.004 GeV/c 200 400 600 800 1000 (a)
3.3 3.4 3.5 3.6 3.7
50 (b)
ηc(1S) χc2(1P) ηc(2S) J/ψ ηc(2S) χc2(1P) Insets: Background subtracted J/ψ: background from ISR events
21
Signal: convolution of Breit-Wigner with detector resolution parameterization Background: Combinatorical: 4th order polynomial J/ψ background: Gaussian
)
2
) (GeV/c
! !
"
"
K
S
m(K 2.6 2.8 3 3.2 3.4 3.6 3.8 4 )
2
Events / ( 0.004 GeV/c 200 400 600 800 1000 (a)
3.3 3.4 3.5 3.6 3.7
50 (b)
ηc(1S) χc2(1P) ηc(2S) J/ψ ηc(2S) χc2(1P)
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γγ → K+K−π+π−π0
BABAR Data sample: 519 fb-1 collected at Y(2S,3S,4S) CMS in
γγ → K0
SK+π−
)
2
) (GeV/c !
+
!
+
m(K 2.6 2.8 3 3.2 3.4 3.6 3.8 4 )
2
Events / ( 0.004 GeV/c 200 400 600 800 1000 1200 1400 1600 (c)
3.3 3.4 3.5 3.6 3.7
50 100 150 (d)
ηc(1S) J/ψ χc2(1P) χc0(1P) ηc(2S) χc2(1P) χc0(1P) ηc(2S) Signals: First observation in K+K-π+π-π0: ηc(1S) [18 σ] ηc(2S) [5.3 σ] χc0(1P) [5.4 σ] (not allowed in KSK+π-) χc2(1P) [4.0 σ] No signal from χc2(2P) Insets: Background subtracted J/ψ: background from ISR events
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(KSK+π-) (K+K-π+π-π0) (KSK+π-) (K+K-π+π-π0)
world average
ηc(1S) m = 2980.3 ± 1.2 MeV/c2 Γ = 28.6 ± 2.2 MeV ηc(2S) m = 3637 ± 4 MeV/c2 Γ = 14 ± 7 MeV
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K+K-π+π-π0 BF
(KSK+π-) (K+K-π+π-π0) (KSK+π-) (K+K-π+π-π0)
Parameters
Belle in B J/ψππK (2003) confirmed by CDF, D0, BaBar
width < 2.3 MeV (90% CL)
Radiative decays C-parity +1,
Spin-parity JP = 1+ or 2-
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Interpretation
χc1(2P) [1++ ], ηc2
(= 1D2) [2-+] mass and width inconsistent with prediction
isospin-violating decay not expected, but J/ψρ (ρ-like ππ-spectrum)
(at threshold: m(DD*) =3871.73 ± 0.29) Decays to J/ψω expected large BF for radiative decays and decays to J/ψππ disagree with molecular picture
neutral, charged partner states not found
Parameters
Belle in B J/ψππK (2003) confirmed by CDF, D0, BaBar
width < 2.3 MeV (90% CL)
Radiative decays C-parity +1,
Spin-parity JP = 1+ or 2-
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Belle (2005) BJ/ψπππK: excess of events in πππ Interpretation as X(3872)J/ψω Old BABAR analysis (2008)
0.7695 < m3π < 0.7965 GeV/c2 (B+) 0.7605 < m3π < 0.8055 GeV/c2 (B0) (ω signal region)
but no evidence of X(3872)J/ψω PRL 101, 082001 (2008)
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)
2
Events / 10 (MeV/c
+
B 200 400
a)
)
2
(GeV/c
! " J/
m
3.8 4 4.2 4.4 4.6 4.8 )
2
Events / 10 (MeV/c B 200 400
b)
B+ J/ψπ+π-π0K+ B0 J/ψπ+π-π0K0 hep-ex/0505037
kinematic limit
Y Y
2
Events/10 MeV/c 200 400 a)
3.85 3.9 3.95 200 400
c)
)
2
(GeV/c
! " J/
m 4 4.2 4.4 4.6 4.8
2
Events/10 MeV/c 200 400 b)
Data Fit function X(3872) Y(3940) Nonresonant
New BABAR analysis
same selection criteria, except 0.7400 < m3π < 0.7965 GeV/c2 (B+) 0.7400 < m3π < 0.8055 GeV/c2 (B0) (ω signal region)
X(3872): Gaussian (resolution) Y(3940): Breit-Wigner x phasespace Nonresonant: mJ/ψω x Gaussian x phasespace
use ω-Dalitz-plot weights
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PRD 82, 011101(R) (2010) B+ J/ψπ+π-π0K+ B0 J/ψπ+π-π0K0
X(3872): m = 3873.0+1.8
Y(3940): m = 3919.1+3.8
Γ = 31+10
X Y X Y
2
Events/7.4 MeV/c 5 10
a)
2
Events/7.4 MeV/c 2 4
b)
)
2
(GeV/c
! 3
m 0.74 0.76 0.78
2
Events/7.4 MeV/c 5 10 15
c) MC S-wave MC P-wave
3π mass for events in X(3872) signal region: 3862.5 < mJ/ψω < 3882.5 GeV/c2
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PRD 82, 011101(R) (2010) B+ J/ψπ+π-π0K+ B0 J/ψπ+π-π0K0
Fit to 3π mass S-wave lineshape: χ2/NDF =10.2/5 P=7% P-wave lineshape: χ2/NDF =3.5/5 P=62% negative parity favored JPC = 2-+ more likely than 1++
nominal ω mass (πππ suppr. near kinem. limit)
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Spin 2
(εB: mean reconstruction efficiency including D branching fractions)
ΓγγxBF(Z(3930)DD)
Spin 2 Spin 0
σ(e+e− → γγ → Z(3930) → DD) = NSignal
B R Ldt
solid line: values from GamGam MC generator
PRD 81, 092003 (2010)
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π+ π0 θh π+π- rest frame PRD 82, 011101(R) (2010)
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mES for events in X(3872) signal region weighting: Background reduced, signal yield constant Crosscheck: events in ηπ+π‐π0 signal region (B J/ψηK) no weighting weighting Signal: ω resonance no weighting PRD 82, 011101(R) (2010)