Frederick A. HarrisFrederick A. HarrisUniversity of HawaiiUniversity of Hawaii

Jan. 5, 2005Jan. 5, 2005

e+ e- physics in the tau – charm energy region

Part I

OUTLINEIntroduction

Oldies but goodiesτ mass measurement and R scan

ψ(2S) scan and radiative and hadronic transitions:ψ(2S) → γγJ/ψ, XJ/ψ

12% Rule and ρπ puzzleψ(2S) → VT and VP

ηC parameters

Summary

The Beijing Electron Positron Collider

L ~ ~5 ×1030 /cm2⋅sat J/ψ peak

Ecm~2-5 GeV

A unique e+e- machinein the τ-charm energyregion from 1989 –

2003.

Beijing, China

BESII Detector

VC: σxy = 100 μm TOF: σT = 180 ps μ counter: σrφ= 3 cm MDC: σxy = 220 μm BSC: ΔE/√E= 22 % σz = 5.5 cm

σdE/dx= 8.5 % σφ = 7.9 mr B field: 0.4 TΔp/p=1.7√(1+p2) σz = 2.3 cm

CLEO-cNew comer to tau – charm energy region.

• Ran at ψ" in 2003 with 6 wigglers (~60 pb-1).

• Running now with all 12.

Luminosity ~0.6 x 1032

pb-1 s-1

• Luminosity expected ~2 x 1032 pb-1 s-1

• 300 pb-1 at ψ" this year?

• Have well understood, state of the art detector.

n 2S+1 L J

Charmonium spectrum below open charm

Charm thresholdψ(3770)

World J/ψ and ψ(2S) Samples (×106)

J/ψ ψ(2S)

0

10

20

30

40

50

60

MarkIII DM2 BESI BESII0

2

4

6

8

10

12

14

MKI MKII MKIII CBAL BESI BESII CLEO

58 M 14 M

Oldies but goodies

Tau mass measurement

• Use e+ + e- →τ+ τ- → e e, e μ, e h, μ μ, μ h, and h h events (+ 4 ν’s). h = π or K

• Use PID plus cuts on kinematic variables.• Fit threshold excitation over 12 scan points • 5 pb-1 of data.

Tau mass measurement• BES measurement:

• 10X better precision

225.018.017.021.0 MeV/c96.1776 ++

−−=τm

J. Z. Bai et al, PRD53, 20 (1996).

Tau mass measurementLeptonic decay rate in SM:

For muon decay, mμ, tμ, and Fcor are used to determine GF

For tau:

Lifetime, leptonic branching ratio, and mass related.

Was poorly satisfied before BES measurement.

),(192

) ( cor3

52

lLLL

lL mmFmGlLπ

νν =→Γ

τ

ννττννττ νντ

tB

Be eee

→→ =Γ=→Γ ) (

(Fcor ~ 1)

μμ ννμ

te e

1) ( =→Γ

Tau mass measurement• Lifetime, leptonic branching ratio, and mass:

Status 1992 (2.4 σ)

and 1994 (1.3 σ)

Status 2000

A. Pich, hep-ph0012297

1992

Tau mass measurementTest lepton universality:

Value should be ~1 if universality holds.

0085.09886.0)( 2 ±=→

→

ννμ

νντ

e

e

GG

0051.00020.1)( 2 ±=→

→

ννμ

νντ

e

e

GG

using PDG2004

Tests universality at ½% level.

With new mτ - 1996

Novosibirsk planning a new tau mass measurement.

R MeasurementR Measurement

PDG2000 – Selected measurements

R provides strong

evidence for the quark

model and 3 colors.

For u, d, s

R ≈ 2

For u, d, s, c

R ≈ 3 1/3

For u, d, s, c, b

R ≈ 3 2/3

R MeasurementR Measurement

Improved R values are very important:

Needed for interpretation

of aμ = (g – 2)/2.

Much of the theoretical

uncertainty from

R - but mostly from

ECM < 2 GeV region.

M. Davier et al., Eur. Phys. J. C31,

503 (2003).

1.9 σ0.7 σ

R measurementR measurementNeeded to improve precision of α(M2

Z):

Uncertainties in α introduced when it is extrapolated to the Z-pole:

Dominant uncertainty due to hadronic vacuum polarization.

This is determined from R values using a dispersion relation.

R measurementR measurementThe Higgs mass determined from radiative corrections in the SM is very sensitive to α(M2

Z).

B. Pietrzyk and H.

Burkhardt (1997).

BES R MeasurementBES R MeasurementDetermination of R:

Runs

~1000 events per energy point

BES R-scan

Results published: J.Z. Bai et.al., Phys. Rev. Lett. 84, 594 (2000).J.Z. Bai et.al., Phys. Rev. Lett. 88, 101802 (2002).59 + 106 citations so far; tau mass paper - 67

BES R MeasurementBES R MeasurementBES Results (continued).

R Below 10 GeV

Before BES R Scan After BES R Scan

BES reduces R errors from 15 – 20 % to an average of 6% in the 2 – 5 GeV region. Important region!

Current StatusBurkhardt and Pietryzk have updated analysis

[Phys. Lett. B513, 46 (2001).]

Error about half previous error.

Shifts Standard Model Higgs mass upward.

Data driven approach:

data for E < 12 GeV

The SM Fit to mH

GeVmGeVm

H

H

17062 53

30

<= +

−

(95% C.L.) GeVmGeVm

H

H

21298 58

38

<= +

−

Without BES dataWith BES data

(95% C.L.)

The Latest SM Fit to mH

GeVmGeVm

H

H

17062 53

30

<= +

−

(95% C.L.) GeVm

GeVm

H

H

260

114 6945

<

= +−

(95% C.L.)

Without BES data

With BES data

Thanks to B. Pietrzyk

In 2004 with new top mass

ψ(2S) scan and radiative and

hadronic transitions

ψ(2S) Scanψ(2S) ScanPurpose: Improve accuracies of ψ(2S) parameters: Γ, Γh, Γμ, Γππ J/ψ,

B(h), B(μ), and B(π+ π- J/ψ).

Ψ(2S) → μ+ μ- and Ψ(2S) → π+ π- J/ψ are importantfor identifying Ψ(2S) decays in B-factory and otherexperiments.

Scanned 24 energy points from 3.67 and 3.71 GeV.Integrated luminosity = 1150 nb-1

Four channels: ψ(2S)→ hadrons, μ+ μ-, e+ e-, and π+π- J/ψ

Fitting

• Fit observed σh(W), σππ J/ψ(W), σe(W), and σμ(W).• Include resonance and continuum production plus

interference, beam spread (Δ), ISR and FSR.• Assume Γe = Γμ = Γτ /0.3885, Γt = Γh + Γμ + Γe + Γτ.

• Determine Γh, Γμ, Γππ J/ψ, M(ψ(2S)), Δ, and R.• Results:

– R = 2.15 ± 0.17 consistent with BES R measurement (R = 2.25 ± 0.06 at 3.55 GeV).

– Δ = 1.298 ± 0.007 MeV. Agrees with expected beam spread.

Fitting Result

Parameter BES MARK I PDG2002264 ± 27(10.1 %) 228 ± 56 (24.6 %) 300 ± 25 (8.3 %)

258 ± 26(10.1 %) 224 ± 56 (25.0 %)

85.4 ± 8.7 (10.1 %)

2.44 ± 0.21 (8.8 %) 2.1 ± 0.3 (14.29 %) 2.19 ±0.15 (6.8 %)

97.8 ± 0.15 (0.16 %) 98.1±0.3 (0.31 %) 98.10 ±0.30 (0.31 %)

32.3 ± 1.4 (4.4 %) 32 ± 4 (12.5 %) 30.5 ± 1.6 ( 5.2 %)

0.93 ± 0.08 (8.5 %) 0.93 ±0.16(17.2 %) 0.7 ±0.09(12.9 %)

(keV)tΓ

(keV)hΓ(keV)ψππ JΓ

(keV)μΓ(%)hB

(%)ψππ JB(%)μB

Phys. Phys. LettLett. B550, 24 (2002). B550, 24 (2002)

Measure:ψ' → πoJ/ψ, ηJ/ψ

ψ'→ γ χcJ → γ γ J/ψ (J=1,2)• Old measurements disagree.• B(ψ’ → πoJ/ψ) very crude:

(23 evts at CBAL, 7 evts at MRK2).• Theoretical predictions for charmonium hadronic

transition amplitudes can be tested by high statistics measurements.

ψ'→ γ γ J/ψ

ηJ/ψ

πoJ/ψ

γ χcJ → γ γ J/ψ

ψ'→ γ γ J/ψ

BKG from πoπoJ/ψ

J/ψ ee or μμ, 5C (J/ψ mass) kinematic fit is applied!

ψ(2S) → ηJ/ψ

ψ'→ γ γ J/ψψ(2S) → πoJ/ψ

γ γ ee

γ γ ee

γ γ ee

γ γ μμ

γ γ μμγ γ μμ

ψ (2S) → γχcJ → γ γ J/ψ

ψ (2S) → γχcJ → γ γ J/ψ

ψ'→ γ γ J/ψ

PDG04 2.67 ± 0.15 1.30 ± 0.08

ψ'→ γ γ J/ψ

πoJ/ψ

ηJ/ψ

γ χc1

γ χc2

BES measures the BRswith high precision!

BES

Phys.Rev.D70:012006,2004

BES most

accurate

ψ'→ γ γ J/ψ

• PCAC [G. A. Miller, Phys. Rep. 194,1(1990)]: R=0.0162 (too small!)

BES (+PDG for ϒ):

R= 0.048 ± 0.007R' < 0.0098R" < 0.0065

• QCD Multipole expansion & BTG potential model[Y. P. Kuang, PRD24, 2874(1981), ibid. 37, 1210(1988)]

R' = 0.0025R" = 0.0013

ψ' → X J/ψB(ψ(2S) → hadrons)/B(J/ψ → hadrons) =

B(ψ(2S) → ggg + ggγ)/B(J/ψ → ggg + ggγ)

= 0.23 ± 0.07

Disagrees with “12 % Rule”

Important to measure ψ’ → X J/ψ and

components.

M. Suzuki, PRD63,

054021, (2001).

Y. F. Gu and X. H. Li,

PRD63, 114019 (2001).

Method – identify J/ψ → μ+μ-

Select muons.

1 C fit to mJ/ψ

determine mX

pX

p μ-p μ+ pJ/ψ

ψ' → X J/ψ

J/ψ peak

Background

e+ e- → γ μ+ μ- and

e+ e- → ψ’ → γ μ+ μ-

Fit distribution:

• background (mμμ < 3.4)

1307 events

• signal 44498 events

Inclusive measurement – use events that satisfy 1 C fit.

ψ' → X J/ψTo separate ψ’ → π0π0 J/ψ and π0π0 J/ψ, plot mX for

no extra charged tracks and for extra charged tracks.

Fit two simultaneously with component shapes.

ππ

η

χc1χc2backgrd

no extra extraππ

η

χ2 < 7

Exclusive measurements

ψ' → X J/ψ

Results

Phys.Rev.D70:012003,2004

measured

BESI – 4 million ψ(2S) events.

Determine ratio of branching ratios to

B(ψ’ → π+ π- J/ψ ) to cancel systematic errors.

Constrain χC2/χc1 since shapes similar.

CLEOc results on ψ(2S) transitions

and radiative decays

From talk by Brian Heltsley at the Third Quarkonium

Working Group Meeting, Beijing, Oct. 12 – 15, 2004.

(www.qwg.to.infn.it)

• Measure inclusive and exclusive.

• 3.1 M (± 3 %) ψ(2S) decays

• Fully reconstruct events

• J/ψ → μμ, ee

• η → γγ, π+ π- π0

• Preliminary

CLEOc ψ(2S) inclusive gamma spectrum

cJS χγψ →)2(

Good calorimeter allows measurement of inclusive spectrum.

Can determine B( ).

Higher than PDG? Yes.cJS χγψ →)2(

(www.qwg.to.infn.it)

12% Rule and ρπ Puzzle

pQCD 12% rule :T. Appelquist & H.D. Politzer, PRL 34 (1975) 43A. De Rujula & S.L. Glashow, PRL 34 (1975) 46

• J/Ψ and Ψ’ hadronic decays proceed via 3 gluons or a virtual photon.cc annihilation → decay rate ~ |ψ(0)|2

• Complications:αS correctionsRelativistic correctionsInterference with continuum (See talk by C.Z. Yuan at 2nd QWG meeting)Etc.

• Take as “Rule of thumb”

12% Rule and ρπ puzzle

12%

eeJ/ψB

eeψ'B

XJ/ψBXψ'B

hQ =−+→

−+→=→

→=

strong electromagnetic non-resonant

ψ(2S) signal continuum

(www.qwg.to.infn.it)

12% Rule and ρπ puzzle

ρπ puzzle:

• Suppression in VP mode (ρπ & K*K ) revealed by MARK-II { M.E.B. Franklin et al, PRL 51 (1983) 963 }

Q(ρπ) < 0.6% Q(K*K) < 2 %

• Suppression confirmed by BESI with higher sensitivity

• Suppression in VT mode found by BESI{ J. Z. Bai et al, PRL 81 (1998) 5080 }

Q(ωf2) < 4.0%, Q(ρa2)< 2.1%, Q(K*K*2) < 1.8%, Q(φf2

’) < 3.7%

Theoretical explanations:Brodsky, Lepage, Tuan: {PRL 59 (1987) 621 } Intermediate vector glueballChaichian & Torngvist : {NP B323 (1989) 75 } Hadronic form factor Pinsky : {PL B236 (1990) 479 } Generalized hindered M1 transitionLi-Bugg-Zou {PR D55 (1997) 1421 } Final-state interactionBrodsky-Karliner {PRL 78 (1997) 4 Intrinsic charm |qqcc> Fock components of

the light vector mesonsChen-Braaten {PRL 80 (1998) 5060 } Fock state with cc pair in a color-octet

Gerard-Weyers {PL B462 (1999) 324 } cc annihilation into 5g via 2 steps

Feldmann-Kroll {PR D62 (2000) 074006 } Decays thru light-quark Fock component by a soft mechanism

Suzuki {PR D63 (2001) 054021 } ψ(2S) - vector glueball mixing

Rosner {PR D64 (2001) 094002 } ψ(2S) - ψ(1D) mixing

J. P. Ma {PR D65 (2002) 097506 } Relativistic Correction

12% Rule and ρπ puzzle

Many ruled out. Still interesting: ψ(2S) - ψ(1D) mixing.

Ψ(2S) → V T ω f2 ↓ ↓

π+π–π0 π+π–

ρ a2 ↓

↓ ρ π↓ ↓ππ ππ

K* K*2

↓ ↓Kπ Kπ

φ f2'

↓ ↓K+K– KK

π+ π– π+ π– π0↓

γ γ

K+ K– π + π –

⇒

⇒

⇒

⇒

Ψ(2S)π+ π– π+ π– π0

↓γ γ

K+ K– K + K –

)1270(2fω

Ψ(2S) → V T

f2 (1270)

B.G.(M.C.)

B.G.( σ )

)1320(2aρ

a2 (1320)

First observation

BESII14 million ψ(2S) events

..)1430()892( 20 cc+ΚΚ ∗∗

Ψ(2S) → V T

B.G.

K*2 (1430)

K*(892)

)1525(2f ′φ

f0(980)f2

' (1525)

First observations

BESII

Ψ(2S) → V T

MCYXS

obsYXS

XS Nn

εψ

ψψ ⋅⋅

=→

→→

→ BB

)2(

)2()2(

VT mode

Bψ(2S) →X (10 – 4)(BES-II)

B J/ψ→X (10 – 3)(PDG2002)

Qh(%)

4.3±0.6 4.8±1.5

2.3±1.1

2.4±1.2

3.9±1.6

10.9±2.2

6.7±2.6

1.23±0.06±0.20†

ω f22.05± 0.41 ±

0.46ρ a2 2.55± 0.73± 0.60

K* K*2

1.64± 0.33 ±0.41

φ f2' 0.48 ± 0.14 ±

0.12† This value from DM2 only

Suppressed!!12 % rule ( pQCD rule )Phys.Rev.D69:072001,2004

BESII

BESII Preliminary

VP Mode ρ π

Dalitz plot for J/Ψ and Ψ(2S) → 3π are very different

J/ Ψ → 3πΨ(2S) → 3π

PRD70 (2004) 012005

Mππ in Ψ(2S) → 3π

ρ(770), ρ(2150) -- dominantBESII Preliminary( PWA )

VP Mode

ρ π

Results on BRs____________________________________________________________________________________________________________________________________________

BR BESII (10 – 5 ) PDG04 (10 – 5 )

Ψ(2S) → π+π-π0 18.1 ± 1.8 ± 1.9 8 ± 5

Ψ(2S) → ρ π 5.1 ± 0.7 ± 0.8 < 8.3

Ψ(2S) →

ρ(2150) π → π+ π- π0 19.4 ± 2.5____________________________________________________________________________________________________________________________________________

BESII Preliminary( PWA )

VP Mode ρ π

2.111.2

+−

hep-ex/0408047 submitted to PRL

Should help the understanding of the ρπ puzzle.

ψ (2S)→ K*(892)K + c.c. → KSKπKS →π+ π-

VP Mode

K*0

K*±

Ψ(2S) → K*±(892) K+ Ψ(2S) → K*0(892) K 0

K*(892)KVP Mode

Br±(2.9±1.3±0.4)×10 –5 Br0(15.0±2.1±1.9)×10 –5

K*±K*0

= 5.2±2.7

65.6±9.0 Evts.

Large isospin-violation

9.6±4.2 Evts.

)( 0 mπKM )( mπ±KM

hep-ex/0407037 , submitted to PRL

ψ’→ Nevt B(ψ’) (×10-5) B(J/ψ) (×10-4)PDG04

Q (%)

ρ (770) π 5.1 ± 0.7 ± 0.8 127 ± 9 0.40 ±0.08ρ (2150) π

ρ η 13.2 ± 4.8 1.78 ± 0.65 ± 0.22 1.93 ± 0.23 9.2 ± 3.7

ρ η’ 2.5 ± 1.7 1.87 ± 1.27 ± 0.36 1.05 ± 0.18 17.8 ± 12.9

ω π 14.0 ±4.8 1.88 ± 0.64 ± 0.32 4.2 ± 0.6 4.5 ± 1.8

ω η <3.3 < 1.1 15.8 ± 1.6 < 0.7

ω η’ 4.1 ±2.8 4.3 ± 2.9 ± 1.0 1.67 ± 0.25 26 ± 19

ϕ π < 3.0 < 0.3 < 0.068

ϕ η 17.8 ± 5.3 3.5 ± 1.0 ± 0.6 6.5 ± 0.7 5.4 ± 1.9

ϕ η’ 9.1 ± 3.6 3.2 ± 1.3 ± 0.6 3.3 ± 0.4 9.7 ± 4.5

K+K*-+c.c. 9.6 ± 4.2 2.9 ± 1.3 ± 0.4 50 ± 4 0.58 ± 0.27

K0K*0+c.c. 65.6 ± 9.0 15.0 ± 2.1 ± 1.9 42 ± 4 3.6 ± 0.8

* PreliminaryUpper limit @90% C.L. Results of VP mode

2.111.25.24.19 +

−±

BESII Preliminary

Test of pQCD

12% Rule

Results

12% Rule to naive

Even more BES

BESII preliminary

Test of pQCD

12% Rule

CLEOc ResultsTalk by Brain Heltsley at Third

Quarkonium Workshop, Oct. 2004. ( www.qwg.to.infn.it )

• ~3 million ψ(2S) events

• continuum data: 20.46 pb-1

(BES 6.42 pb-1)

• CLEOc subtracts continuum without considering interference.

• For ρπ, no PWA. Just use ρ(770) peak. Neglect interference.

CLEOc Results

Upper limit @90％ C.L. BESII vs. CLEO (ψ’ BRs Results) BESII Preliminary

• Most channelsBRs are consistent.

• BES BR(ρπ) > CLEO by ~ 3σ,

because PWAtakes into acount theinterference.

• BR(K*0K0) aredeviated

CLEO BRs calculated from hep-ex/0407028

12% Rule and ρπ puzzle

• There are many new measurements from BES and

CLEOC.

• Agreement is good, especially if differences

in continuum subtraction taken into consideration.

• These should help to explain the ρπ puzzle.

ηc parameters

ηc ParametersPrecise (mJ⁄ψ - mηc) needed for potential models.But ηc mass not well determined: PDG02 CL = 0.001

Width Measurements

Values spread all over with large errors.

M(pp)

J/ψ→γ ηC , ηC →pp

ηC measurements with BESII 58 M J/ψ sample

M(K+K-π+π-) M(π+π- π+π-)

M(K+/- K0Sπ-/+)

M(φφ)

J/ψ→ γηC , ηC → K+ K- π+ π- J/ψ→ γηC , ηC → π+ π- π+ π-

J/ψ→ γηC , ηC → K KS π J/ψ→ γηC , ηC → φ φ

Results: Mass and WidthResults: Mass and WidthCombined fit of five channels:

M(ηC) = 2977.5 ± 1.0 ± 1.2 MeV/c2

Γ(ηC) = 17.0 ± 3.7 ± 7.4 MeV/c2

PDG

M(ηC) = 2979.7 ± 1.5 MeV

Γ(ηC) = 16.0 +3.6-3.2 MeV

Phys. Phys. LettLett. B555, 174 (2003). B555, 174 (2003)

Results: Mass and WidthResults: Mass and Width

PDG2004

BES2003BaBar BaBar

BaBar Γ = 34.3 ± 2.3 ± 0.9 MeV/c2

γγ production – 88 fb-1 of data

hep-ex/0311038,

Phys. Rev. Lett. 92: 142002 (2004).

Results: Branching Fractions

SystematicErrors

Product BranchingFractions

Results: Branching FractionsResults: Branching FractionsDividing by B(J/ψ → γ ηc ) = 1.3 ± 0.4 % (PDG2002)

† H.C. Huang et al., hep-ex/0305068

* Calculated from results in F. Fang, et al., PRL 90:071801,2003.

B(ηc → φ φ) is smaller than PDG and agrees with Belle

measurement (hep-ex/0305068).

Physics Letter B578, 16 (2003).

*

†

*

Summary

BES has

• Made fundamental measurements of the τ mass and R in the 2-5 GeV energy region. Important for testing lepton universality and the SM.

• Improved ψ(2S) parameters from a ψ(2S) scan and measurements of radiative and hadronic transitions.

ψ(2S) → π0 J/ψ, η J/ψ, π0π0 J/ψ, γχcJ, and anything J/ψ.

• Measurements for BRs of ψ(2S) → VP channels: ψ(2S) → (ρ,ω,ϕ)(π,η,η’), K*Ko In ψ(2S) → 3π, ρ(770) & ρ(2150) dominant.o Large isospin-violation in ψ(2S) → KK* channel.o Results agree well with CLEOc.

• Measured ηC mass, width, and branching ratios.

Thanks