Recent BES BES Results and the Results and the BESIIIBESIII UpgradeUpgrade

Frederick A. HarrisFrederick A. HarrisSept. 11, 2007Sept. 11, 2007

For the BES CollaborationFor the BES Collaboration

Menu2007IKP, ForschungzentrumJuelich, GermanySept. 10-14, 2007

OUTLINEOUTLINE• Introduction• BESII physics

•ψ′ → ττ•ψ’ BB-bar•ψ’ radiative decays•J/ψ, ψ(2S) → ΛΛπ0 & ΛΛη•J/ψ and ψ (2S) → nK0

SΛ•ψ(3770), ψ(4040), ψ(4160),

ψ(4415)• BESIII• TOF calibration system• Summary

Introduction – BESCM Energy ranges from 2 to 5 GeVLuminosity at J/ψ ~ 5 x 1030 cm–2 s -1

Detector Performance:

A unique e+e- machine in the τ-charm energy region since 1989 – until CLEOc.

Beijing, China

BESII

World J/ψ and ψ(2S) Samples (×106)

BES: J/ψ 2001 – 58 M ψ(2S) 2002 – 14 M

0

10

20

30

40

50

60

MarkIII DM2 BESI BESII0

5

10

15

20

25

30

MKI MKII MKIII CBAL BESI BESII CLEO

2006Many papers based on these BESII samples.

BESII Physics

B(ψ′ → ττ) = 2.71 ± 0.43 ± 0.55 - first measured by BESI:[PRD65, 052004 (2002)]:

ψ′ → ττ

BESI:

According to sequential lepton hypothesis, branchingratios expected to satisfy:

ψ′ → ττBESII

Remeasure with larger sampleMeasure in ψ′ → ττ → (μντνμ)(eντνe)Characterized by

•2 charged tracks; 1 μ and 1 e•missing energy and momentum•no extra hits in BSC

ε = 17.8%

BESII ψ′ → ττ

Result:

B(ψ′ → ττ) = (3.10±0.21±0.38) x 10-3

Bee (10-3) Bμμ (10-3) Bττ/0.3885 (10-3)PDG07 PDG07 BESII

7.43 ± 0.18 7.4 ± 0.8 8.0 ± 1.1

Lepton universality is tested in charmonium decays.

PRD 74: 112003 (2006)

ψ’ BBbarFirst measurement by BESI, remeasure BR with BESII data sample.

pp-bar

ΛΛ-bar

ΣΣ-bar

ψ’ pp

ψ’ → ΛΛ→ pπ-pπ+

ψ’ → Σ0 Σ0

→ γpπ-γpπ+ ΞΞ-barψ’ → Ξ- Ξ+

→ p2π-p2π+

Consistent with “12% rule”.

K*Kρπ

MARK-II

0

0.5

1

1.5

2

2.5

3

3.5

4

BES

CLEO

ψ’ BBbar

BESII – CLEOccomparison

pp-bar ΛΛ-bar ΣΣ-bar ΞΞ-bar

Consistent with SU(3) symmetry.

Reduced Branching Ratios

R = Br/(π p* /s½), p* is baryonmomentum.

R’s same under SU(3) symmetry.

BES

Phys. Lett. B648, 149 (2007)

+−−+−+

−+−+−++−−+−+

+−−+

ΚΚ ,

+,ΚΚ ,

,ΚΚ ,

→+→)(

•][ ,ΚΚ→)(

,

•

)(2)3(:prong-6

..),2(,pp)2(:prong-4 ,pp :prong-2

X X2

data. BESII with modes more Measure)2003(032004,672-

(1998)] 101[PRD58,097 - BESIby measured modes few aOnly

'

ππππ

πππππππ

ηππππ

γψ

ππγγψγηγη

ccKKKK

S

PRDS

S

ψ’ radiative decays

First measurements of ψ’ radiative decays

Mode BR (×10-5)[m<2.9 GeV/c2]

γ pp-bar 2.9 ± 0.4 ± 0.4

γ η’ 12.6 ± 2.9 ± 1.5

γ 2(π+π-) 39.6 ± 2.8 ± 5.0

γ KSK+π-+c.c. 25.6 ± 3.6 ± 3.6

γ π+π-K+K- 19.1 ± 2.7 ± 4.3

γ π+π-ppbar 2.8 ± 1.2 ± 0.7

γ 2(K+K-) < 4.0

γ 3(π+π-) < 17

γ 2(π+π-)K+K- < 22

• Expect ~1% BR, but only 0.05% previously observed.• ~ 0.1% more observed in this analysis.

PRL 99, 011802 (2007)

PRD74, 072001 (2006).

J/ψ and ψ(2S) → ΛΛπ0 and ΛΛηJ/ψ → ΛΛπ0 measured by DM2 and BESIB(J/ψ → ΛΛπ0 ) = (2.2 ± 0.6) x 10-4 PDG – isospin violating

ψ(2S) → ΛΛπ0 unmeasuredJ/ψ and ψ(2S) → ΛΛη unmeasured – isospin conserving

SelectJ/ψ → ΛΛπ0 → (p π-)(pπ+)γγRequire:

4C kinematic fit, χ2 < 10L > 5 mm|M(p π) – M(Λ)| < 10 MeV/c2

BackgroundJ/ψ → Σ0 Σ0

andM(ΛΛ) < 2.8 GeV/c2

J/ψ and ψ → ΛΛπ0 and ΛΛη

signal shape

Use similar selection forJ/ψ → ΛΛ η

J/ψ → ΛΛ π0: BES finds large background from J/ψ → ΣπΛ.Must measure BR for this process.

signal shape

N(J/ψ → ΛΛπ0) < 7.0

Clear signal.N(J/ψ → ΛΛη) = 44 ± 10

Preliminary

Backgroundsbiggest fromJ/ψ → ΣπΛ

J/ψ and ψ → ΛΛπ0 and ΛΛη

hep-ex: 0707.1127First measurement!

Preliminary

ψ(2S) → ΛΛπ0 , ΛΛ η

No signals seen.

signal shapes

J/ψ and ψ (2S) → nK0SΛ and c.c

In 2004, BES published a threshold enhancement in J/ψand ψ(2S) → pK-Λ.

ψ(2S) → pK-Λ

For J/ψ → pK-Λ – S wave BW fit:M = 2075 ± 12 ± 5 Mev/c2

Γ = 90 ± 35 ± 9 Mev/c2

B(J/ψ → K- X) B(X → pΛ)= (5.9 ± 1.4 ± 2.0) x 10-5

Also see one in M(KΛ)

J/ψ → pK-Λ

M(KΛ) GeV/c2

PR 93:112002 (2004).

J/ψ and ψ (2S) → nK0SΛ and c.c.

Here study:J/ψ → nK0

SΛ + c.c. → n π+ π- p π + + c.c.

Require K0S and Λ :

|M(ππ) – M(K0S)| < 12 MeV/c2

|M(pπ) – M(Λ)| < 20 MeV/c2

Lxy(Λ) > 5 mm

χ2 (1C) < 5Lxy(K0

S) > 5 mm

Further:

signal

K0SΛ

Preliminary

n

See KΛ enhancementconsistent with PWA in pKΛ.[Int. J. Mod. Phys.,A 552, 344 (2005)].

Fitting with simple BW:

M = 1648 ± 6 Mev/c2

Γ = 61 ± 21 Mev/c2

(errors stat. only)

But no obvious nΛ thresholdenhancement like in pK Λ.B(J/ψ → KS X)B(X → nΛ +c.c.)< 4.8 x 10-5 (90% CL)Not inconsistent.

J/ψ and ψ (2S) → nK0SΛ and c.c.

J/ψ → nK0SΛ + c.c. → n π+ π- p π + + c.c.

Possible interesting structures.

Preliminary

Λ*sN*s

J/ψ and ψ (2S) → nK0SΛ and c.c.

Signal

ψ(2S) → nK0SΛ + c.c.

→ n π+ π- p π + + c.c.use similar selection

PreliminaryResultsB(J/ψ → nK0

SΛ + c.c.)= (6.42 ± 0.20 ± 0.99) x 10-4

B(J/ψ → nK0SΛ)

= (3.09 ± 0.14 ± 0.56) x 10-4

B(J/ψ → nK0SΛ)

= (3.37 ± 0.14 ± 0.45) x 10-4

B(ψ(2S) → nK0SΛ + c.c.)

= (0.77 ± 0.11 ± 0.13) x 10-4

B(J/ψ → K0SX) B(X → nΛ + c.c.)

< 4.8 x 10-5 (90% CL)

Qh = B(J/ψ → nK0SΛ + c.c.)

B(ψ(2S) → nK0SΛ + c.c.)

= (12.0 ± 3.2)%(consistent with 12% rule of pQCD)

ψ(3770), ψ(4040), ψ(4160), ψ(4415)In 1998 and 1999, BES scanned 91 energy pointsbetween 2 and 5 GeV to determine R.

Phys. Rev. Lett. 84, 594 (2000) and 88, 101802, (2002).

ψ(3770), ψ(4040), ψ(4160), ψ(4415)

In the calculation of ISR factor (1+δ), the values of resonant parameters in PDG2000 were used.

Here we refit to determine parameters of high massJPC = 1-- states.

Use Breit Wigner amplitudes with arbitrary phase to describe resonances:

Allow interferences betweenresonances.

Resonant parameters

ψ(3770), ψ(4040), ψ(4160), ψ(4415)

Use 2nd order polynomial for charm continuum. (Compare to DASP phenomenological form.)

Use potential model variable hadronic width. (Compare with Effective Interaction Theory model.)

Must fit using iterative procedure - resonant parameters will influence (1+δ) and then Rexp.

Other models: The results are not the same, but are consistent within errors.

For details, see hep-ex: 0705.4500

The new results

preliminaryhep-ex: 0705.4500

The new resultsComparison of the updated R value and the old results in Phys. Rev. Lett. 88 (2002)101802

Differences in R values are due to the updated resonant parameters and initial state radiative correction factor (1+δobs).

preliminary

hep-ex: 0705.4500

Resonant parameterspreliminary

BEPCII/BESIII

BEPCII: a high luminosity double–ring collider

SC RF

Beam magnets

BEPCII Design goal

Energy range 1 – 2.1 GeV

Optimum energy 1.89 GeV

Luminosity 1 x 10 33 cm-2s-1 @ 1.89 GeV

Injection Full energy injection: 1.55 − 1.89 GeV Positron injection rate > 50 mA/min

Synchrotron mode 250 mA @ 2.5 GeV

Use many bunches and mini-beta.

BEPCII Status• Nov. 2006 – start commissioning; beam stored in storage ring.

• June 2007 - SR radiation for users at 2.5 GeV/c; 200 mA, τ = 5.5 hr.

• Aug. 2007 – beam current reached 0.5 A.

• At present: moving SC quads to IR; machine studies to start.

• BESIII detector to IR in Mar. 2008; commissioning summer 2008.

BESIII Detector

Be beam pipe

SC magnetMuon Counter

Drift Chamber

CsI(Tl) calorimeter

TOF

MDCParametersR inner: 63mm ; R outer: 810mm Length (out.): 2582 mm Inner cylinder: 1.2 mm Carbon fiberOuter cylinder: 11.5 mm CF with 8 windowsSense wire : 25 micron gold-plated tungsten (plus 3%Rhenium ) --

- 6796 Layers (Sense wire ): 43

Expected performance

Field wire: 110 micron gold-plated Aluminum --- 21884Gas: He + C3H8 (60/40)Cell: inner chamber --- 6 mm

outer chamber --- 8.1 mmPolar angle: |cos θ| < 0.83 (all layers)

< 0.93 (20 layers)%6~

@1GeV/C%5.0~

130~

dxdE

P

m

dxdE

P

x

σ

σμσ

MDC construction

MDC wiring

resrevoverallEntries 781908Mean -2.772e-05RMS 0.123

/ ndf 2χ 2234 / 154Prob 0p0 24.2± 5551 p1 1.416e-04± 9.471e-05 p2 0.00022± 0.07865 p3 23.5± 2245 p4 0.000456± -0.000392 p5 0.0008± 0.1854

Residual (mm)-1 -0.8 -0.6 -0.4 -0.2 -0 0.2 0.4 0.6 0.8 10

5000

10000

15000

20000

25000

30000

35000resrevoverall

Entries 781908Mean -2.772e-05RMS 0.123

/ ndf 2χ 2234 / 154Prob 0p0 24.2± 5551 p1 1.416e-04± 9.471e-05 p2 0.00022± 0.07865 p3 23.5± 2245 p4 0.000456± -0.000392 p5 0.0008± 0.1854

mμ=120σ

=80HT

=60, VLTV

Cosmic ray test of completed MDC

resolution 120 μm

MDC ready forinstallation in detector.

CsI(Tl) crystal calorimeter• Design goals:

– Energy: 2.5% @ 1GeV– Spatial: 0.6cm @ 1GeV

• Crystals:– L = 28 cm (15 X0)– Barrel: 5280 w: 21564 kg– Endcaps: 960 w: 4051 kg– Total: 6240 w: 25.6 T

Mechanical structure

Assembly of Barrel EMC

Insertion

EMC Status:• Barrel assembly

complete.• End cap begun.

View from inside

TOFCrucial for particle ID• Barrel

– 50mm x 60mm x 2320 mm (inner layer).

– BC408 – 2 layers – 88 in each– Radius from 810 to 930 mm.

• Endcap– 48 fan shaped pieces – each

end.– BC404

• PMT: Hamamatsu R5942fine mesh

TOF – IHEPTOF electronics - USTC

Coil: single layer solenoid Cooling mode: two phase helium force

flowSuperconductor: Al stabilized NbTi/CuWinding: inner windingCold mass support: tension rodThermal shield: LN2 shield, MLIFlux return: barrel/end yoke, pole tip

Superconducting MagnetCryostat

Inner radius 1.375m

Cable dimension 3.7mm*20mmElectrical parameters

Central field 1.0TNominal current 3650A

Stored energy 10MJCold mass 3.6tonTotal Weight 15ton

Inductance 2H

Radiation thickness 2X0

Outer radius 1.7mLength 3.91m

CoilMean radius 1.482mLength 3.52m

First of its kind built in China.

BESIII SC Magnet ProgressThermal insulation assembly

transportation

wiring

installation

0 500 1000-0.018

-0.016

-0.014

-0.012

-0.010

-0.008

-0.006

-0.004

-0.002

0.000

0.002

0.004

0.006

VTL1A-VTL2A VTLL1A-VTLL2A VTLL1B-VTLL2B VTLL3A-VTLL4A VTLL3B-VTLL4B VTM6A-VTM1A VTM6A-VTM5A VTM1A-VTM2A VTM3A-VTM4A VTM4A-VTM5A

Vol

tage

(V) Time:22:00Time:19:00

Voltage curve shows that the magnet is in super-conducting state.

Magnetic field 10029.8 Gauss.

BESIII SC Magnet ProgressSept. 19, 2006

Field mapping of magnet completed.

Spring 2005: All RPC production, assembly, testing, and installation completed.

Physics Topics at BESIIIOpen charm factory :

• Absolute BR measurements of D and Ds decays• Rare D decay• D0 - D0bar mixing• CP violation• f D+, fDs form factors in semi-leptonic D decays• precise measurement (1.6% stat.) of CKM (Vcd, Vcs)• CP violation and strong phase in D Dalitz Decays• light meson spectroscopy in D0 and D+ Dalitz Decays.

Physics Topics at BESIII

• Charmonium: J/ψ, ψ(2S), ηC(1S), χC{0,1,2} , ηC(2S), hC(1P1), ψ(1D), etc. • New Charmonium states above open charm threshold• Exotics : hybrids, glueballs, and other exotics in J/ψ and ψ(2S)

radiative decays.• Baryons and excited baryons in J/ψ and ψ(2S) hadronic decays.• Mesons and mixing of quark and gluon in J/ψ and ψ(2S) decays.• Electromagnetic form factors and QCD cross section (R values).• tau mass and tau physics near the threshold

Very rich and interesting energy region.

Resonance Mass(GeV)CMS

Peak Lum.(1033cm-2s-1)

Physics Cross Section (nb)

Nevents/yr

J/ψ 3.097 0.6 3400 10 × 109

τ 3.670 1.0 2.4 12 × 106

DsDs 4.030 0.6 0.32 1.0 × 106

ψ(2S) 3.686 1.0 640 3.2 × 109

D0D0bar 3.770 1.0 3.6 18 × 106

D+D- 3.770 1.0 2.8 14 × 106

DsDs 4.140 0.6 0.67 2.0 × 106

Average Lum: L = 0.5×Peak Lum.; One year data taking time: T = 107s

Nevent/year = σexp ×L× T

Production

Huge J/ψ and ψ(2S) samples at BESIII

BESIII Collaboration

Institute of High Energy PhysicsUniversity of Science and TechnologyPeking UniversityTsinghua UniversityShangdong UniversityNankai UniversityCentral China Normal UniversityUniversity of AnhuiUniversity of ZhejiangUniversity of ZhengzhouNanjing Normal UniversityNanjing UniversityShanxi UniversitySichuan UniversityHenan Normal University

University of HawaiiUniversity of WashingtonUniversity of TokyoJoint Institute of Nuclear

Research, DubnaGSIUniversity of BochumUniversity of Giessen

Need more here!

BESIII TOF Monitoring System

Monitor the amplitude and time performance of each channel including PMTs and electronics. Concept:

Use fiber cable bundles (2 cables) to distribute light to barrel and endcap TOF counters.Use light splitter to illuminate one bundle at a time.

BESIII TOF Monitoring System

TOF endcap 48 fibers

TOF endcap 48 fibers

LaserDiode

Light splitter

TOF barrelPMT PMT

Ref. PMTsTo TOFelectronics

Fiber

TOF barrel 176 fibers

TOF barrel 176 fibers

Electronic switchFiber bundles

fiber

connectorBeam splitter

Use PicoQuant 440M Laser Diode (440 nm).– Simple to use and maintain.– Long lifetime (6 k hours at

full power).– Peak power: ~1W– Pulse width < 70 ps.– Wavelength 440 ± 10 nm.– Power stability 1% RMS.– 1.5 x 108 photons/pulse.

BESIII TOF Monitoring System

PicoQuant LDH-P-440M

Fiber Bundle Cables (need 2)

Barrel TOF

EC TOF

Time difference measurementScheme: LD illuminates common end; measure time differencebetween reference fiber and all other fibers.

Laser diode illuminating common end of bundle through diffuser.

Barrel distribution boxes. One set of distribution fibers. Two distribution fibers connected

to reference PMTs.

Summary• Many results from BESII J/ψ and ψ' data sets.

Only presented a few.• BEPCII/BESIII progressing well.• Commissioning in summer 2008. • Rich physics program after CLEO-c. Complementary to B-factories.

• Collaborators welcomed!