Galina Pakhlova ITEP&Belle rnational Workshop on Heavy Quarkonia 2008 December 2008, Nara Women's University
Dec 30, 2015
Galina Pakhlova ITEP&Belle
International Workshop on Heavy Quarkonia 20082-5 December 2008, Nara Women's University
Galina Pakhlova2
Two main reasons to know charm components of R
To shed light on the nature of the charmoniumlike “1–– family” with masses above open charm threshold
To provide model independent information on the parameters of the JPC = 1–– charmonium states spectrum above open charm threshold
R(s) = σ(e+e–→hadrons, s)/ σ(e+e–→μ+μ–, s)
Galina Pakhlova3
Y(4260)
Y(4325)Y(4660)
Y(4008)
Curious 1– – family
Galina Pakhlova4
e+e−→ 1– – final states via ISR
ISR physics at B-factories • Quantum numbers of final states are fixed JPC = 1– –
• Continuous ISR spectrum: access to the whole s interval em suppression compensated by huge luminosity
• comparable sensitivity to energy scanning (CLEOc, BES
c
c
e-
s=E2cm-2EEcm
e+
e–
e+
1– –
Galina Pakhlova5
PRL 99, 182004 (2007)
550 fb-1
2-BW fit with interference • two solutions: different peak cross sections
Y(4008)7.4σ Y(4260)
PRL 99, 182004 (2007)
550 fb-1
2-BW fit with interference • two solutions: different peak cross sections
Y(4008)7.4σ Y(4260)
Two or one states in e+e–→J/π+π– γISR ?Y(4260)
454 fb-1
344±39 ev
Y(4008)
arXiv:0808.1543
NEW
Absence of open charm production is inconsistent with conventional
charmonium
< 0.7 90% CL
7.5±0.9±0.8
Br(J/π+π–)Γee , eV
Solution1 Y(4008) Solution2
Solution1 Y(4260) Solution2
(2S)First Y(4260)PRL 95,142001(2005)
233 fb-1
8σ
(2S)First Y(4260)PRL 95,142001(2005)
233 fb-1
8σ
Confirmed PRL 96,162003(2006)
+ J/00 (5.1σ)
11σConfirmed PRL 96,162003(2006)
+ J/00 (5.1σ)
11σPRD74,091104R(2006)
13.3 fb-15.4σ
PRD74,091104R(2006)
13.3 fb-15.4σ
Galina Pakhlova6
Y(4360)→(2S)ππ
PRL 98, 212001 (2007)
298 fb-1
Y(4660) ?
e+e–→(2S) π+π– γISR
Y(4360), Y(4660) ...
2-BW fit with interference
Absence of open charm production is inconsistent with conventional charmonium
Y(4360) 8σ
Y(4660) 5.8
670 fb-1
PRL 99, 142002 (2007)
Y(4360)
Y(4360)
Galina Pakhlova7
Y states vs inclusive cross section e+e–→hadrons
Peak positions for M(J/) & M((2S)) significantly differentY(4008) mass is close to (4040)Y(4260) mass corresponds to dip in inclusive cross section
(3
770)
if Ruds=2.285±0.03 Durham Data Base
Y(4
008)
(4
040)
(4
160)
Y(4
260)
Y(4
325)
(441
5)
Y(4
660)
Galina Pakhlova8
Interpretations of Y states Problem:
No room for Y states among conventional 1– – charmoniumquark model S.Godfrey and N.Isgur PRD32,189 (1985)
• 33S1= (4040), 23D1 = (4160), 43S1 = (4415) are measured • masses of predicted 33D1 (4520), 53S1 (4760), 43D1(4810) higher(lower) Y masses
OptionsY(4325) = 33D1 , Y(4660) = 53S1 with shifted masses
G.J Ding et al Phys.Rev.D77:014033 (2008) A.M.Badalyan et al arXiv:0805.2291
Charmonium hybrids Zhu S.L.; Close F.E.; Kou E.and Pene O.
• are expected by LQCD in region 4.2-5 GeV• the dominant decay Y(4260)→DD1 (threshold 4287 MeV)
Hadro-charmonium • Specific charmonium state “coated” by excited light-hadron matter
S.Dubinskiy, M.B.Voloshin, A.GorskyMultiquark states• [cq][cq] tetraquark Maiani L., Riquer V., Piccinini F., Polosa A.D.• DD1 or D*D0 molecules Swanson E.; Rosner J.L., Close F.E.
S-wave charm meson thresholds Lui X.
Galina Pakhlova9
Charmonium states contribution
to inclusive cross section e+e−→ hadrons
above open charm threshold
ψ(3770), ψ(4040), ψ(4160), ψ(4415) have been known for more then 25 years
M, Γtot, Γee are quite uncertain
• To fix the resonance parameters one needs to know their decay channels to take into account their interference:
• How to take into account non-resonant contribution?• How to take into account many open charm thresholds?
Galina Pakhlova10
Resonance shapes Interference term
Rres=RBW+Rint
Phys.Lett.B660,315(2008)
Last fit to the inclusive R spectrum
To reduce model dependence need to measure exclusive cross sections e+e−→D(*)D(*)
The interference is taken into account • model dependent
Significant effect of interference
Galina Pakhlova11
D
D
s=E2cm-2EEcm
e+
e–
e+
reconstructed
not reconstructed
if undetectable
Full reconstruction of hadronic part
ISR photon detection is not required
• but used if it is in the detector acceptance
e+e– →DD via ISR
with full reconstruction
Galina Pakhlova12
Combinatorial bgs are estimated from D sb Other bgs are small and taken into account
γISR is not detected
Consistent with ISR production
DD
e+e− DD at s~3.7−5 GeV via ISR
γISR is detected
670 fb-1
D+D–
D0D0
Phys.Rev.D77,011103(2008)
• D0D0 or D+D– (full reconstruction)
• no extra tracks
• detection of γISR is not required
• if γISR is detected
• M(DDγISR) is required ~ Emc
Galina Pakhlova13
e+e– D(*)D(*)cross section calculation
Measured D(*)D(*) mass spectra
Differential ISR luminosityTotal efficiency
Translate measured mass spectra to cross sections:
D(*)D(*)
Galina Pakhlova14
σ(ee→D+D−)/σ(ee →D0D0) = 0.72±0.16±0.06
at MDD≈M(3770) is consistent with BES&CLEOc
(4040)
(4160)
(4415)
670 fb-1(3770)
Broad structure around 3.9 GeV is in qualitative agreement ?? with coupled-channel model Phys. Rev. D21, 203 (1980)
Some structure between (4040) and (4160)
• Statistics is small
Hint of (4415)
σ(e+e− →DD)
Galina Pakhlova15
Phys.Rev. D76, 111105(2007)
σ(e+e− →DD)
Phys.Rev.D77,011103(2008)
arXiv:0801.3418
Durham Data Base
Galina Pakhlova16
D(*)
D
s=E2cm-2EEcm
e+
e–
e+
π
reconstructed
not reconstructed
but constrained
D*
DD* & D*D*
D* partial reconstruction • increase eff ~ 10-20 times
detection of ISR photon
e+e– →D(*)D* via ISR
with partial reconstruction
Galina Pakhlova17
e+e–→D(*)D* with partial reconstructionPhys. Rev. Lett. 98, 092001 (2007)
D*+D*- D+ D*-
Mrec(D*+γISR) Mrec(D*+γISR)
ΔMrecΔMrec
MD*
with ΔMrec cut
σRMD~1 MeV
MD*
Reconstruction of D(*) γISR
• wide peak in Mrec(D(*)γISR) at M D*
• contribution from e+e–→D(*)D* (n)πγ
Reconstruction of D(*) γISR + πslow from unreconstructed D* • wide peak in Mrec(D(*)π-γISR) at MD
Use recoil mass difference Mrec = Mrec(D(*)γISR) - Mrec(D(*)πγISR)
• narrow peak at (MD* - MD)• cancellation of momentum smearing
• Tight ΔMrec cut small background
Use kinematical constraint Mrecoil(D(*)γISR) →MD* to improve resolution
Galina Pakhlova18
D*+D*-
D+D*-
550/fb
(4040)
(4415)
Phys. Rev. Lett. 98, 092001 (2007)
(4160)
Y(4260)
Exclusive e+e–→D(*)D* cross-sections
Y(4260) signal DD* : hint, but not significant D*D* : clear dip (similar to inclusive R) • Systematic errors ≈ statistical errors
(4160)
(4040)
arXiv:0801.3418
(4160)
(4040)
Durham Data Base
Backgrounds are reliably estimated from the data
Galina Pakhlova19
D
D
s=E2cm-2EEcm
e+
e–
e+
π
reconstructed
not reconstructed
if undetectable
D0 D− +
full reconstruction of hadronic part
ISR photon detection is not required • but used if it is in the detector acceptance
Three body final states
Galina Pakhlova20
e+e− D0D–+ at s ~ 4−5 GeV via ISR
D0 D− π+ full reconstruction no extra tracks
Clear (4415)DD signal
similar analysis and bgs no major bgs except for combinatorial
Consistent with ISR production
670 fb-1
Galina Pakhlova21
Resonant structure in (4415)DD
Br((4415) D(D)non D2(2460))/Br((4415) DD*2(2460))<0.22
M = 4411± 7 MeVΓtot =77±20 MeV
Nev= 109± 25
Consistent with BES,Phys.Lett.B660,315(2008)
PDG06, Barnes at.al Phys. Rev. D72, 054026 (2005)
M(D0π+) vs M(D–π+) from (4415) region Clear D*
2(2460) signals
Constructive interference No non-D*
2(2460) contribution
DDπ non DD*2(2460)
DD*2(2460)
~10σ
670 fb-1
Phys.Rev.Lett.100,062001(2008)
σ(e+e–→(4415))×Br((4415)→DD*2(2460))×Br(D*
2(2460) →Dπ)=(0.74±0.17±0.07)nb
Galina Pakhlova22
Reconstruct Λc+
anti-proton tag from inclusive Λc–→p–X
Br(Λc+→pX) = (50±16)%
• combinatorial background
suppressed by a factor of 10
detect the high energy ISR photon
Λc+
X
s=E2cm-2EEcm
e+
e–
e+
p
reconstructed
not reconstructed
Λc–
─
Partial reconstruction with anti-proton tag Charm baryons final states
p tag ─
Galina Pakhlova23
e+e–→Λc+Λc
– γISR
Λ c sidebands
Mrecoil(Λc+γISR)
Λc–
Λc–(2595)
Λc–(2625)
Λc–(2765)
Λc–(2880)
no Σ–
partial reconstruction with p tag ─
Clear peak in Mrec(Λc+ISR )
distribution at Λc mass. Wide shoulder for mass >2.5GeV/c2
contributions from Λc+Λc
–π0 • could proceed via Λc
+Σ– ; violates isospin and should be highly suppressed
and Λc+Λc
–π π • could proceed via Λc
+Λc(2595)–, Λc
+Λc(2625)–, Λc+Λc(2765)–,
Λc+Λc(2880)–Apply asymmetric requirement on Mrec(Λc
+ISR ) to suppress tail from Λc
+Λc–π0 and Λc
+Λc–π π reflection
Total refection contributions < 5% (included in systematics)
Use kinematical constraint Mrecoil(ΛcISR) M Λc to improve resolution Look at Mrecoil(ISR) ≡ Mass spectra of Λc
+Λc–
Galina Pakhlova24
670 fb-1
X(4630) 8.2
Phys.Rev.Lett.101,172001(2008)
e+e–→Λc+Λc
– γISR
NEW
e+e–→Λc+Λc
– γISR
PRL 99,142002(2007)
ee→ΛΛ via ISR
PRD73,012005(2006)
ee→pp via ISR
PRL 99,142002(2007)
ee→ΛΛ via ISR
PRD73,012005(2006)
ee→pp via ISR
• no peak-like structure
PRL 97, 242001 (2006)
6.2σ B–→Λc+p π–─
PRL 97, 242001 (2006)
6.2σ B–→Λc+p π–─
• dibaryon threshold effect • like in B→pΛπ, J/→γpp
Interpretations for the new X(4630)
•53S1 charmonium state • in some models M (53S1) ~4670MeV
• Something else...
• X(4630) = Y(4660)? JPC=1––
Galina Pakhlova25
Contribution to the inclusive cross section
D*D*
DDπ
DD*
DD
Λc+Λc
–
Galina Pakhlova26
D*D*
DD*
(4
040)
(4
160)
Y(4
008)
(4
415)
Y(4
660)
Y(4
260)
Y(4
360)
DD
DDπ
Λc+Λc
–
?
PRD77,011103(2008)
PRL100,062001(2008)
σ(e+e–→open charm) via ISR
NEW
PRL98, 092001 (2007)
Phys.Rev.Lett.101,172001(2008)
(3
770)
if Ruds=2.285±0.03
Durham Data Base
Y(4
008)
(4
040)
(4
160)
Y(4
260)
Y(4
360)
(4
415)
Y(4
660)
Belle: Sum of all measured exclusive contributions
Y states vs exclusive cross sectionsY(4008) mass coincides with DD* peak Y(4260) mass corresponds to dip in D*D* X-sect.
Y(4660) mass is close to Λc+Λc
– peakEnhancement near 3.9 GeV in ee→DD coupled channel effect?
(4415) more contributions to be measure
Galina Pakhlova27
In conclusionFive exclusive open charm final states were measured
DD, DDπ, D*D, D*D*, ΛcΛc
Their sum is close to e+e– → hadrons
Belle & BaBar &Cleo_c cross sections measurements are consistent with each other in corresponding energy ranges
D*D* (main contribution)• complicated shape of cross section • clear dip at M(D*D*) ~ 4260GeV (similar to inclusive R)
DD* (main contribution)• broad peak at threshold (shifted relative to 4040 GeV)
DD • complicated shape of cross section • broad enhancement ~ 3.9 GeV – coupled channel effect?
DDπ (4415) signal observed, dominated by (4415)→DD2 (2460)
ΛcΛc
• Enhancement at threshold, mass and width are consistent with Y(4660)
Galina Pakhlova28
All presented cross sections could be found in Durham Data Base
In conclusion
Theoretical efforts to describe charm components of R are kindly requested!
Galina Pakhlova29
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