Transcript Document

5th International Conference on Quark Confinement, Gargnano, Italy, September 10-14, 2002
Heavy Quark Production and Decay
in the Upsilon region:
Results from Belle
•Hadronic physics in the Upsilon region
•Belle and KEKB
•Selected Results:
Prompt J/y and double charm production
Observation of hc’
Production of charmonia in B decay
Rate of h’ from B decay
•Summary
Kay Kinoshita
University of Cincinnati
Belle Collaboration
Heavy quarks in the  region
}B{
b
(4S)
in cms, Ec=Ee, ~1 nb
c
} meson
} meson
in cms, EB=Ee, ~1 nb
most c-hadrons have
p>(kinematic limit for b->c)
Well-defined (& measureable!)
production rate, energy
At Belle, ∫L(4S)dt/∫L(<4S)dt~0.10
BB threshold
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Beams: KEKB
bg = 0.425
(E*beam) = 2.6 MeV
IP size = 77µm(x) x 2.0µm(y) x 4.0mm(z)
Lmax = 7.4 X 1033 cm–2s–1 (design: 1x1034)
Data (6/1999–7/2002)
Ldt = 89.6 fb–1@(4S), 9.0 fb–1off
(~9x107 B, c events)
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Belle detector
Charged tracking/vertexing
- SVD: 3-layer DSSD Si µstrip
– CDC: 50 layers (He-ethane)
Hadron identification
– CDC: dE/dx
– TOF: time-of-flight
– ACC: Threshold Cerenkov (aerogel)
Electron/photon
– ECL: CsI calorimeter
Muon/KL
– KLM: Resistive plate counter/iron
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Belle Collaboration
274 authors, 45 institutions
many nations
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Prompt J/y production (PRL88, 052001 (2002))
29.4 fb-1(4S)+3.0 fb-1(<4S)
(explains y(2S) excess @ FNAL):
Test of NRQCD
e+e- -> J/y gg (dominant) + J/y g + J/y cc (~10%)
Predict ~0.8-1.7 pb, peak @ pmax from J/y g
Measure e+e-->J/yX, y(2S)X, search c1X, c2X
subtract y(2S) contribution to J/yX for J/ydirectX
+momentum spectra
+polarization(momentum)
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Prompt J/y
Results
J/y
y(2S)
Spectra
• softer than expectation
for J/y gg
• ~ expectation for J/y cc
• No peak @ pmax* (from J/y g)
Polarization
• no significant p* dependence
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(hep-ex/0205104; 41.8 fb-1(4S), 4.4 fb-1(<4S))
: predictions vary 0.07 -> few pb
•  region: high rate, S/B for
•
= clean signature for sea-c
• high L of B-factory compensates for low e.
Outline of analysis
• find J/y -> e+e-, µ+µa) search for B->J/y{ }: plot “recoil mass”
Mr2 = Er2 - pr2  -py
Ebeam-Ey
-> Mr2 = (Ebeam-Ey)2-py2
resolution improved ~ 2x via constraint: Ey2 - py2 = My2
b) search for associated D*+, D0
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a)
J/y mass sideband
Event selection:
Nchg≥5
with J/y
mass constraint
hc
c0
hc’
(J/y J/y forbidden by C)
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b)
Reconstruct
D*+ -> D0π+ {D0->K-π+, K-K+, K-π-π+π+, Ksπ+π-, K-π+π0}
net
D0 -> K-π+, K-K+
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b)
Average:
Conclusion:
Not consistent with NRQCD
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Observation of hc’
History
Theory:
Exp’t:
In B decay:
B{
(PRL 89, 102001 (2002); 41.8 fb-1)
M~3625-3645 MeV/c2
M=3594±5 MeV/c2 (Xtal Ball, PRL48,70(1982))
(several unsuccessful attempts to verify)
} charmonium
Unrestricted in J,P,C
-> spectroscopy
B->hcK observed (CLEO), hc’, hc expected to decay similarly
->search in observed hc channels
Outline
Search for B->hc’K+, hc’Ks {hc’->KsK-π++c.c.}
Reject bg: B->D(Ds)X, K*->Kπ
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Observation of hc’
bins of M(KsKπ)
Kinematics for final selection:
DE E*cand–E*beam 0
(E*beam s0.5/2)
~13 MeV
Mbc (Beam-constrained mass)
Mbc (E*beam2-p*cand2 )0.5
!
|DE|<0.04 GeV
!
Simultaneous fit, each bin of M(KsKπ):
Mbc , DE{5.271 < Mbc < 5.287 GeV/c2}
M(hc’)=3654±6±8 Mev/c2
104±14
M(hc)=2979.8±1.8
Mev/c2
39±11 consistent w
theory
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Charmonia in B decay
Test of factorization approximation:
} Factorizable ( no gluon req’d)
modes dominate
for color-suppressed modes
Factorization-violating
B--> c0K- (PRL88,052001 (2002)) 29.1 fb-1(4S), 2.3 fb-1(<4s)
B -> c2X
<- c0->ππ BR
(PRL89,011803 (2002)) 29.4fb-1(4S), 3.0 fb-1(<4s)
cf:
Conclude: non-factorizable/factorizable=o(1)
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B->h’K
(PLB 517, 309 (2001)
10.4 fb-1(4S)
Theory:
B(B->h’K+)~(21-53)x10-6
B(B->h’K0)~(20-50)x10-6
Experiment - history:
CLEO, first indication of anomalously high B (new physics?)
B(B->h’K+)x106
B(B->h’K0)x106
Belle:
in h’->hππ, h’->g
Consistent with CLEO,
somewhat larger than
theory->need more data
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Summary
Belle 1999-2002: rapidly increasing L
Large sample of B, c events
to test many aspects of hadronic physics
Intriguing results:
• NRQCD fails to describe
• hc’ mass consistent with potential model
• factorization approx. fails for B->charmonium
• hint of anomalously high rate for B->h’X
Next
• systematics improving
• data - 90 fb–1; increasing - 8617 pb–1/mo
• new developments in theory?
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