Transcript Phi2Psi - Novosibirsk

Rc measurement
at B-factories
Galina Pakhlova
ITEP
Belle collaboration
22.09.2011
Historical remarks on inclusive measurements
 states were discovered at e+e– colliders
(4415) MARK-I 1976, DASP 1978
 (3770) MARK-I 1977, DELCO 1978, MARK-II 1980, BESII 2005
 (4040) and (4160) DASP 1978
Total cross section
e+e–  hadrons
Crystal Ball 1986
BESII 2005
CLEO 2009
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Exclusive measurements of  state decays
 Only (3770)
non-DD decays problem
 The single measurement of D and D* meson production
at Ecm= 4.028 GeV Phys.Lett.B 69, 503 1977
 The single measurement of Λc production at Ecm= 5.2 GeV
Phys.Rev. Lett. 44, 10 1980
Phys.Lett.B660,315(2008)
 BESII fit of R spectrum
Phys.Lett.B660,315 2008
All possible two-body decays of
ψ(3770), ψ(4040), ψ(4160), ψ(4415)
Rres=RBW+Rint
model-dependent results
Resonance shapes
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Interference term
Luminosity at B factories
Not only B-Factories but
Charm-Factories as well
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Radiative return in LO
ISR
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FSR
ISR measurements at B-factories
 Fixed quantum numbers of final state JPC = 1– –
 Study of open charm final states from threshold in wide energy region
 Huge accumulated luminosity at B factories
 Limited statistics
 strong electromagnetic suppression
 typical events topology: fast photon with small pt
 Specific reconstruction methods
 e.g. D+D*– & D*+D*–
 partial reconstruction of D*– to increase efficiency by 10-20
 reconstruction of ISR photon
 measurements of recoil mass against γISR ≡ mass of D(*)+D*–
 translation of D(*)+D*– mass spectrum to cross section
 e.g. D+D–
 full reconstruction of hadronic part
 no reconstruction of ISR photon
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Two-body
final states
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Phys.Rev. D77, 011103(2008)
Belle, BaBar, CLEO: σ(e+e− →DD)
Phys.Rev. D76, 111105(2007)
Phys.Rev. D80, 072001(2009)
CLEO: narrow range 3.97 - 4.26 GeV
no radiative corrections
problem of direct comparison with B-factories results
 Wide structure near 3.9 GeV
 Good agreement between
Belle и BaBar
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 agreement with coupled channel model
Structure at 4.0 - 4.2 GeV
 (4040)? (4160)?
 First hint of (4415) →DD
Belle, BaBar, CLEO: σ(e+e−→D(*)D*)
Phys. Rev.Lett. 98, 092001 (2007)
Phys.Rev. D79, 092001(2009)
 Good agreement between Belle и BaBar
 Belle measurements more accurate than BaBar
Phys.Rev. D80, 072001(2009)
CLEO: 3.97 - 4.26 GeV
ψ(4160)
ψ(4040)
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no radiative correction
problem of direct comparison
with B-factories results
ψ(4040)
ψ(4160)
Ds+Ds*–
Ds+Ds–
Ds*+Ds*–
e+e– → Ds(*)+Ds(*)–
The single measurement of
CLEO 2009
Energy scan with high
accuracy but in narrow
region 3.97 - 4.26 GeV
Problems
 Cross sections of charm strange mesons were found to be order
of magnitude less than cross sections of D(*)D(*)
 Ds* Dsγslow
 very low efficiency of soft photons at threshold
 multiple counting due to lots of soft photons in event
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Belle measurements of e+e– → Ds(*)+Ds(*)–
Full reconstruction method similar to DD
(4040)
(4160)
Ds+Ds–
Ds+Ds*–
Ds*+Ds*–
(4415)
Sum of e+e– → Ds(*)+Ds(*)–
(4160)
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Y(4260)
(4040)
(4415)
 Ds+Ds–
peak at threshold near (4040)
 Ds+Ds*–
peak at threshold near (4160)
and (4415)
dip near Y(4260) mass
Ds+Ds–
Ds+Ds–
Ds+Ds*–
Ds+Ds*–
Ds*+Ds*–
Belle, BaBar, CLEO: e+e– → Ds(*)+Ds(*)–
BaBar: Bin size of 100 MeV is too large to observe
relatively narrow structures
Belle & BaBar are in agreement within errors
CLEO: 3.97 - 4.26 GeV
no radiative corrections
Ds*+Ds*–
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Ds+Ds–
Ds+Ds*–
Three-body
final states
D0 D(*)− π+
Full reconstruction method
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Cross section of e+e− D0D–+
Phys.Rev.Lett.100,062001(2008)
(4415)D0D–+
670 fb-1
M = 4411 ± 7 МэВ
Γtot = 77 ± 20 МэВ
Nev= 109 ± 25
In agreement with BES
Phys.Lett.B660,315(2008)
PDG06, Barnes at.al
Phys. Rev. D72, 054026 (2005)
σ(e+e–→ψ(4415))×Br(ψ(4415)→DD2(2460))×Br(D2(2460) →Dπ) = (0.74 ± 0.17 ± 0.07)nb
Br((4415)  D(D)non D2(2460))/Br((4415) DD2(2460))<0.22
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Cross section of e+e− D0D*–+
Upper limit
ψ(4415)
Phys.Rev.D 80, 091101 (2009)
Y(4260)
ψ(4415)
σ(e+e–→ψ(4415))×Br(ψ(4415)→D0D*–π+)< 0.76 nb at 90% CL
Br(ψ(4415)→ D0D*–π+) < 10.6 % at 90% CL
UL at 90% CL
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First final state with charm baryons
e+e–→Λc+Λc–
 (5S) or (4D) J.Segovia, A.M.Yasser, D.R.Entem,
F.Fernandez
 (6S) B.Q.Li and K.T.Chao
 influence of (3D) E.Beveren, G.Rupp
 (2S)f0(980) molecule
F.K.Gou,C.Hanhart, S.Krewald,U.G.Meissner
 tetraquark D.Ebert, R.N.Faustov, V.O. Galkin
 hexaquark M.Abud,F.Bucella, F.Tramontano
 charm baryonium G.Gotugno, R.Faccini,
A.Polosa
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X(4630) ≡ Y(4660)? JPC=1– –
DD
DD*π
DD*
D*D*
DDπ
Exclusive cross sections contribution
to the total cross section
ΛcΛc
DsDs +DsDs* +Ds*Ds*
Contributions of D+D*–, D*+D*–, D0D–π+ and D0D*–π+ are
scaled following isospin symmetry
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In conclusion...
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Search for charmonium-like states
Y family
 no peaks near Y states mass in exclusive open charm cross
sections
 X(4630) ?
 minima near Y(4260) mass in cross sections of e+e– → D*+D*–,
Ds(*)+Ds(*)–
 predictions of dominant decays of Y(4260)  DD(*)π were not
confirmed
X(4630)
 quantum numbers, mass and width are in agreement with
Y(4660)
 does not mean that X(4630) ≡ Y(4660)
 lots of interpretations – absence of clear understanding of
X(4630) nature
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Status and perspectives
 Almost all measured cross sections are included into Durham
Hep Data Base
 Parameters and branchings of observed decays of (4415), σ(ee
D0D0)/σ(eeD+D−) for (3770), upper limits on YDD*π are
included to PDG tables
Obtained results are important for physical programs of
experiments at e+e– colliders
 KEDR at VEPP-4M
 BESIII at BEPCII
 c-τ factory in Novosibirsk
 Belle II at SuperKEKB
 ... and for theory
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(4040)
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(4160)
Y(4260)