Decays at CLEO
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Transcript of Decays at CLEO
Decays at CLEO
Steve BluskSyracuse University
for the CLEO Collaboration
Preview Introduction Measurements of B((nS) +- ) Electric Dipole Transitions (1S) ( c c ) + X Summary
Preview Introduction Measurements of B((nS) +- ) Electric Dipole Transitions (1S) ( c c ) + X Summary
ICHEP’04, Beijing, China Aug 16-22,2004
BottomoniumBottomonium
JPC
1-- (bb) states couple to virtual photon
(1S)- (3S) too light to form B mesonsggg and qq decays dominant, but suppressed. States are narrow ! EM and hadronic transitions to lower-lying bb states competitive
(4S)BB; Weak Int. Physics
n2S+1LJ J=L+S
Photon TransitionsE1: |L|=1, S=0: 3 2| | | |f f f fE n L R n L
M1: L=0, |S|=1: 3 2 2( / ) | | | |b f f f fE m n L R n L E1 >> M1
Hyperfine(spin-spin) splitting
Spin-orbit3PJ3P0,1,2
CLEO III
Detector & Data Samples
(1S)
(2S)(3S)
106
Analyses presented here makeextensive use of the excellent CsIcalorimeter, tracking and muonsystems
CsI: 6144 crystals (barrel only): E/E ~ 4% at 100 MeV ~2.5% at 1 GeV
Tracking
Measurement of B((nS)) Goal: Extract tot.of (nS) .
tot << Ebeam cannot be extracted by scanning the resonance. Use: tot= ee / Bee = ee / B where Bll=B((nS)+-); (assumes lepton universality) B((nS)) also important for (nS) EM & hadronic BF’s.
We actually measure:
Which is related to B by:
( ) ( )/ /had nS nS hadronsN N B
/(1 3 )B B B
(nS) Event Selection Exactly 2 back-to-back oppositely charged muons < 2 showers with E>50 MeV
(nS)hadrons Event Selection >2 charged tracks For Ntrk<5: (Ecc> 0.15Ecm) & (Ecc<0.75Ecm or Esh
max<Ebeam) Evisible > 0.2Ecm
(nS) efficiency: (65.2±0.2)%
(nS)hadrons efficiency: (97-98)%
Background dominated by cascade decays:e.g. (2S) (1S) 00/ (2S) : (2.9±1.5)% (3S) : (2.2±0.7)%
Nsh < 2Nsh 2
M/Ebeam
(2S)(1S)X, (1S)
(2S)
(2S) Data
ICHEP ABS10-0774
B(%) B(%)B(%)
Results(1S) (2S) (3S)
N 344,908 ± 2485 119588 ± 1837 81179 ± 2660
0.652 ± 0.002 0.652 ± 0.002 0.652 ± 0.002
Nhad 18,957,575 ± 11729 7,838,270 ± 8803 4,641,369 ± 12645
had 0.979 ± 0.016 0.965 ± 0.013 0.975 ± .014
Interference corr. 0.984 0.961 0.982
B (%) 2.49 0.02 0.07 2.03 0.03 0.08 2.39 0.07 0.10
tot (keV) 52.8 ± 1.8 29.0 ± 1.6 20.3 ± 2.1
PDGtot (keV) 53.0 ± 1.5 43.0 ± 6.0 26.3 ± 3.4
(1S) in goodagreement with previousmeasurements
(2S), (3S) significantly larger than current world average values
Electromagnetic
Transitions
Aim is to get precision measurements of masses and transition rates. Tests of LQCD & effective theories, such as potential models or NRQCD.
We present results on Inclusive Analyses of E1 transitions: (2S)bJ(1P) (3S)bJ(1,2P)
Can be used to extract E1 matrix elements and extract relative importance ofspin-orbit and tensor interactions.
C. Davies, et al, PRL 92. 022001 (2004)
Inclusive (2S)bJ(1P)
e+e-
hadrons
hadrons
(2S) Branching
Fraction (%)Photon energy
(MeV)
b0(1P) 3.750.120.47
162.560.190.42
b1(1P) 6.930.120.41
129.580.090.29
b2(1P) 7.240.110.40
110.580.080.30
Raw
Backgroundsubtracted
hadrons
Preliminary
Dominant Systematics B: Shower Simulation & Fitting E: Calorimeter calibration
(3S) Branching Fraction (%)
Photon energy(MeV)
b0(2P) 6.770.200.65121.550.160.4
6
b1(2P) 14.540.180.73
99.150.070.25
b2(2P) 15.790.170.73
86.040.060.27
b0(1P) 0.300.040.10 -
Inclusive (3S)bJ(1,2P)
(2S)b(1PJ) (1DJ)b(1Pj)
(3S) b(1P0) (3S) b(1P2) +
(3S) b(1P1) +
b(1PJ) (1S)
(3S)bJ(2P)
(3S)bJ(1P)
100 50 200EMeV
EMeVPreliminary
Summary of (2S) bJ(1P) Results (Preliminary)
EE
BB
(2S)b(1P2) (2S)b(1P1) (2S)b(1P0)
2 1
1 0
0.57 0.01 0.01m m
rm m
Gives quantitative information on the relativeimportance of spin-orbit & tensor forces
Summary of (3S) bJ(2P) Results (Preliminary)
EE
BB
(3S)b(2P2) (3S)b(2P1) (3S)b(2P0)
2 1
1 0
0.58 0.01 0.01m m
rm m
Charmonium Production in (1S) Decay History: CDF observes J/, (2S) ~10x, 50x too large. Braaten & Fleming propose color-octet (CO) mechanism; J/ produced perturbatively in CO state and radiates a soft-gluon (non-perturbatively) to become a color-singlet (CS); <ME> fit to data. Problems though: J/ polarization data from CDF, e+e-J/+X from BaBar & Belle, J/ at HERA .
Suggestion by Cheung, Keung, & Yuan: If CO is important, the glue-rich decays of should provide an excellent labortatory for studying the role of the CO mechanism in production. Distinct signatures in J/ momentum spectrum (peaking near endpoint).
Li, Xie & Wang show that the Y(1S)J/+ccg may also be important (2 charm pairs)
Li, Xie & Wang, PLB 482, 65 (2000)
Cheung, Keung & Yuan, PRD 54 929 (1996)
B((1S)J/+X) 6.2x10-4 5.9x10-4
Momentum Spectrum Soft Hard
Previous CLEO measurement based on ~20 J/ events: B=(11±4)x10-4
ICHEP ABS10-0773
Event Selection & Signals Data Sample: 21.2x106 (1S) decays Reconstruct J/, e+e- Backgrounds:
Radiative return: suppressed through Ntrk, Emax, and Pev
miss requirements Radiative Bhabha (ee only): veto events where either electron can form M(e+e-)<100 MeV. cJ: Negligible after Ntrk and Pev
miss requirements. e+e-J/+X continuum: Estimated using (4S) data and subtracted.
Efficiencies: ~40% (~50%) for J/ (J/ee); small dependence on momentum, cos
(1S)J/+X e+e-J/+X below Y(4S)
(1S)J/+X
B((1S)J/+X)=(6.4±0.4±0.6)x10-4
Spectrum much softer than CO prediction Somewhat softer than CS prediction Very different from continuum
Continuum Background
(e+e-J/+X)=1.9±0.2(stat) pb
BaBar(e+e-J/+X)=2.52±0.21±0.21 pb, PRL87, 162002 (2001) Belle(e+e-J/+X)=1.47±0.10±0.13 pb,
PRL88, 052001 (2002)
Normalization to (1S) Data * Luminosity ratio * Phase space ratio: 0.78±0.13
9.46 10.56 2
/ /* / (10.56 / 9.46)GeV GeV
e e J X e e J X
BaBar
First Observations/Evidence(1S)(2S)+X (1S)cJ+X
( (1 ) (2 ) )0.41 0.11 0.08
( (1 ) / )
B S S X
B S J X
2
1
0
( (1 ) )0.52 0.12 0.09
( (1 ) / )
( (1 ) )0.35 0.08 0.06
( (1 ) / )
( (1 ) )7.4
( (1 ) / )
c
c
c
B S X
B S J X
B S X
B S J X
B S X
B S J X
CO & CS both predict ~20%
c1, c2 BF’s ~2x CO prediction
(4S) Continuum
SummaryCLEO has the world’s largest sample of (1S), (2S), and (3S) data sets Precision measurements in (bb) spectroscopy (rates, masses) provides a unique laboratory for probing QCD. Glue-rich environment is ideal for studying color-octet predictions
Recent work also includes: Searches/limits for M1 transitions (b) First observation of a (1D) state (first new (bb) state in 20 years!) Measurements of new hadronic transitions (e.g., b1,2(2P)(1S)) Searches for anomalous couplings Many other interesting topics are in the pipeline Exclusive 2 and 4 transitions in (3S) decays New measurements of ee for (1S), (2S), (3S) (1S,2S,3S)Open Charm (1S) , K*K, etc (“puzzle”) Searches for LFV …
Backup Slides
The Physics
The (1S)- (3S) resonances are the QCD analogy of positronium - bb are bound by the QCD potential:
e.g. V(r)= – 4/3 s/r + kr
Large b quark mass (v/c)2 ~ 0.1 non-relativistic to 0th order(In some models, relativistic corrections added to non-relativisticpredictions)
In much the same way that positronium allowed for a greater understanding of QED, the masses, splittings between states and the transition rates provide input into understanding QCD.
Tests of lattice QCD Important for flavor physics ! Test of effective theories, such as QCD potential models
Coulomb-like behaviorfrom 1-g exchange
Long distancebehavior, confiningk~1 GeV/fm
Electric Dipole Transitions
2321 )12(
27
4)( SnrPnEJePnSn ifQfiE
After normalizing out the (2J+1)E3 between
different J’s, we obtain:
b(2P):(J=2) / (J=1)
(J=0) / (J=1)
(J=0) / (J=2)
1.000.010.05
0.760.020.07
0.760.020.09
b(1P):(J=2) / (J=1)
(J=0) / (J=1)
(J=0) / (J=2)
1.010.020.08
0.820.020.06
0.810.020.11
c(1P):(J=2) / (J=1)
(J=0) / (J=1)
(J=0) / (J=2)
1.500.020.05
0.860.010.06
0.590.010.05
In the non-relativistic limit, the E1 matrix element is spin independent.
In NR bb system, (v/c)2~ 0.1 expect ratios ~ 1 NR corrections O(<20%) for J=0
Also shown are (cc), which show sizeabledifferences (v/c)2~0.3; mixing between 23S1and 13D1 states may also contribute.
Comparison with various models
E1=B(niSnfP)tot((nS))Using:Uses newCLEO tot
valuesWe can extract | | f in P r n S
Relativistic corrections needed for (cc)
In (bb) system, NR calculations in reasonable agreement with data.
o = predictions (non-relativistic)▲ = spin-averaged predictions (relativistic)
time
Spin-Orbit & Tensor InteractionsResponsible for splitting the P states 3PJ
Can express:
MJ=2 = Mcog + aLS - 0.4aT
MJ=1 = Mcog - aLS + 2aT
MJ=0 = Mcog - 2aLS - 4aT
where
2 02
1 1| (2 0.5 ) |LS
b
da nP V V nP
m R dR
32
1| |
12Tb
a nP V nPm
Spin-Orbit Coeff.
Tensor Coeff.
V0= static potential; V2,3= spin-dependent potentials(both model-dependent)
Data on mass-splittings can be used to extract aLS and aT,
Experimentally, the mass splittings are most precisely determined using
01
12
mm
mmr
CLEO3 CLEO2
r (1P) 0.570.010.01 0.540.020.02
r (2P) 0.580.010.01 0.570.010.01
Our results indicate that there is no difference between the different radial excitations of the P waves in (bb) system.
Search for b in (3S) b(1S) and (2S) b(1S)
(2S) b(1S) (3S) b(1S)
b(2PJ) (1S)
(2S) Data
b(1PJ) (1S)
Hindered (ninf) M1 transition suppressed by 1/mb
2
Large differences amongmodels
(3S) Data
(3S) b(2S) (2S) b(1S) (3S) b(1S)
CUSBII(PRD46,1928(1992)) vs CLEOIII
£(3S)~200/pb £(3S)~1300/pb
~10% (poor segmentation of calorimeter) ~60% Also it seems that they had worse energy resolution.
We are very surprised that they claimed comparable accuracy to ours.
(3S) b(2PJ)
e+e-J/+X using on Y(4S) Data, pJ/>2 GeV
Y(1S) & Y(4S) Overlayed