cleoiii upsilon results
Post on 14-Jan-2016
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CLEOIII Upsilon results• In principle, includes:• CLEO-III dipion transitions between vectors
– Complements CLEO05 results on transitions between L=1 P-states
• High-precision measurement of dielectronic width of Y(1S), (2S) (3S)
• Many radiative results:– Observation of exclusives already presented:
– Upper limits on and ’ modes
– UL on multibody modes (>=4 charged tracks)
– Comparison of inclusive quark/gluon production in radiative decays of Y vs. qq+photon (ISR)
CLEOIIICLEAN signals, angular analysis underway.
Dipion transitions
• Renewed interest in `double-bump’ structure in (3S)(1S) following BaBar observation of 4S(nS)
Goal: spin/parity analysis across invariant mass to determine whether low-mass bump is sigma0 – if not, what is it?
Exclusives: Multibody modes
• Exclusive radiative events‘bumps’ in the inclusive (scaled to Ebeam) photon spectrum (assume narrow recoil object)• We perform a series of fits to the inclusive photon spectra as a function of E in order to set an E-dependent upper limit on these radiative events.
• Nota bene: ‘bumps’ in the inclusive photon spectra can also be caused by continuum threshold effects (ccbar, e.g.)
*→+, →4 MC
An example, albeit exaggerated, of signal . . . (10-2)
Method (Fitting Spectrum)
• We fit each step to a Gaussian+Chebyshev polynomial
• Step along the photon spectra with the Gaussian mean
• Fix Gaussian sigma at each step to be the detector resolution (~1% @ 5 GeV)
• Looking for narrow resonances so the measured photon energy dist. should be Gaussian with Gaussian width E.
Efficiencies (*→+, →?)
4 592% 2p2K0 505% 480 602%
4K 502% 22K0 532% 6 743%
4p 672% 420 591% 6K 684%
2p2 623% 4K20 492% 6p 524%
2p2K 562% 4p20 632%
22K 533% 2p220 635%
40 602% 2p2K20 572%
4K0 482% 22K20 543%
4p0 652% 440 572%
2p20 545% 460 602%
Worst
Phase Space
High Mult.
All limits on the order of 10-4
•Embed signals at a given level into data. •We then apply our procedure to the resulting spectra
• We construct all signals above our upper limit floor (~10-4) in our accessible recoil mass range
In/Out and Sensitivity Check
A(M
)+
1.6
45*
A(M
)
dN
/d(A
/A)
(<
(1S
))
A/A
Check of pulls:
Continuum data
Results
• Our sensitivity is of order 10-4 across all accessible values of M
• Above the threshold for any known B((1S)→+pseudoscalar, pseudoscalarh+h-h+h-+neutrals)
• We measure for all M:B((1S)→+,4 charged tracks) < 1.05 x 10-3
B((2S)→+,4 charged tracks) < 1.65 x 10-3
B((3S)→+,4 charged tracks) < 5.70 x 10-3
Results (2)
• Restricting M to 1.5 GeV < M < 5.0 GeV we measure:B((1S)→+,4 charged tracks) < 1.82 x 10-4
B((2S)→+,4 charged tracks) < 1.69 x 10-4
B((3S)→+,4 charged tracks) < 3.00 x 10-4
• We report these upper limits as a function of recoiling mass M (see conf. Paper)• B.R.’s are all ~10-4. • N.B. Not in conflict with any observed two-body radiative decays to-date (due to 4-charged track requirement here)
Many modes!
Dedicated search for 1S and 1S’;
Observed in J/psi decay at 10-4 and 4.7x10-4 level
Only upper limits quoted at this time…
Suggests dedicated search for (1S)c?
Quarks v. Gluons
•1981 (CESR): e+e- collisions (ECM ~ 10 GeV) produce ; ggg allows high-statistics study of gluon fragmentation
•Isolate gluons: ggg decay of Isolate quarks: fragmentation
•1984 Find: more baryons/event in ggg decay than
•Weakness: 3 partons (ggg) vs. 2 partons ( ) 3 strings (ggg) vs. 1 string ( )
•Solution: decay of vs. decay of continuum
gg
• e+e- Z0
(LEP)
Y(1S)3gluons, but also 2-gluon source:
•e+e- (CLEO)
• e+e- (1S) (CLEO)
gg
gqq
ggg
Z0
gqq
Data Sets
Data Set Luminosity (1/fb) ECM (GeV)
1S 1.19 9.46
2S 1.07 10.02
3S 1.42 10.36
4S 5.52 10.58
Below 4S 2.10 10.55Note that for 2S and 3S have not corrected for cascades:
(2S) (1S) + X(3S) (2S) + X (3S) (1S) + X
Are included as consistency checks, but have subtractions and corrections that have not been included.
Method: vs. qqggg
•Bin according to particle momentum
•Count N(Baryon) per bin and normalize to hadronic event count
•Enhancement is:
Continuum-subtracted Resonance Yield
Continuum Yield
Enhancement = 1.0 Particle is produced as often on resonance as on continuum
Method: vs.
•Bin particle yield recoiling against high-E photon according to tagged photon momentum
•Count N(Baryon) per bin and normalize to photon count in that bin
•Enhancement is:
Continuum-subtracted Resonance Yield
Continuum Yield
Enhancement = 1.0 Particle is produced as often on resonance as on continuum
qqgg
Λ p p φ
Detector and Generator Level: ggg
manageable bias; use correction factor where appropriate; discrepancy in/out used for systematics
•Successfully reproduce CLEO84 indications of baryon enhancement in 1S (ggg) vs. CO ( ) fragmentation
•Comparison of baryon production in 1S ggγ vs. e+e- (comparing two gluon to two quark fragmentation)
-1S gg baryons shows much reduced enhancement relative to baryons -Effect not reproduced in JETSET MC
Proton f2 results
Ggg/qqbar Ggγ/qqbargamma Ratio
p 1.30 ± 0.01 1.10 ± 0.02 ~ 1.2
Antip 1.33 ± 0.01 1.19 ± 0.03 ~1.1
Λ 2.56 ± 0.02 1.97 ± 0.03 ~1.3
φ 0.85 ± 0.03 1.1 ± 0.3 ~0.8
f2 0.66 ± 0.04 1.4 ± 0.9 ~0.5
Deuteron Production (Preliminary)
B(1S(ggg+ggd+X=
2.86(0.30)x10-5
Per event enhancement of deuteron production in gluons vs. quarks ~12.0(2.0). Also: note 1Spsi >> continuumpsi
Summary
• Radiative decays (in general) continue to be more elusive than for J/psi
• Baryon coupling to 3-gluons confirmed (even larger for deuterons!); enhancement in 2-gluons mitigated.
• Ramping down these efforts (CLEO-III CLEOc)
• Future improvements/results hopefully to emerge from B-factories with dedicated Upsilon running
• Thanks to everyone who did the work!
•Reproducing CLEO84 indications of baryon enhancement in 1S(ggg) vs. CO ( ) fragmentation
•New comparison of baryon production in 1S ggγ vs. e+e- comparing two gluon to two quark fragmentation -First time such a comparison has been made
•Essential results: -1S gg baryons shows much reduced enhancement
relative to baryons -Effect not reproduced in JETSET MC
•Additional cross-checks (2S, 3S, comparison with mesons) included
Overview
p and p: 2S/3S data corrected
Data Results: ggg
Λ: 2S corrected
Data Results: ggγ
Method (Extracting Limit)
• Plot the gaussian area A(x) from fits to inclusive photon spectra
• Convert into an upper limit contour with height=A(x)+1.645*A(x)
• A(x) is the Gaussian fit sigma
• Negative points → 1.645*A(x)
• Divide on-resonance fits by efficiency corrected number of (1S), (2S) and (3S) events (-1events) •Divide off-resonance fits by luminosity of off-resonance running and derive xsct UL’s
• Note: +f2(1270) will not show up in this analysis since B (f2 4 tracks) is approximately 3%• B ((1S)+, +-, +-0) << 10-4
The M-Dependent Upper Limits
CHECK OF PULL DISTRIBUTIONS
Fragmentation Models
•Simplistically there are two models: Parton vs. String
•Parton: g or q radiates a new particle
•String: g and q are connected by a string (gluon). Particles move apart; string stretches and breaks; forms new particles
•String model is what is in JetSet MC (CLEO: Jetset 7.4 PYTHIA) Parameters tuned to √s = 90 GeV LEP Data
e+
e-
q
q
Data Results
•Show data and detector level MC enhancements for both ggg and ggγ
•“Corrected” data and generator level MC enhancements for those with a low CL fit.
•Systematic errors have been introduced based on the correction factor.
Λ p p φ f2
1
Data Results: Momentum-Integrated
Λ p p φ f2
1
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