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CLEOC/BESIII— New Frontiers of  -C Physics. Z.G. Zhao University of Michigan, Ann Arbor, MI, USA IHEP of CAS, Beijing, China. I . CLEOC /CESRC and BESIII /BEPCII II. Physics Over View III. Current Status Suggestions to BESIII V. Summary. . KEKB. PEPII. BEPCII.

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cleoc besiii new frontiers of c physics
CLEOC/BESIII—New Frontiers of -C Physics

Z.G. Zhao

University of Michigan, Ann Arbor, MI, USA

IHEP of CAS, Beijing, China


II. Physics Over View

III. Current Status

  • Suggestions to BESIII

V. Summary

current operating e e colliders








Peak Luminosity

(1/1030 cm-2s-1)





Current Operating e+e- Colliders






  • Modify CESR for low-energy operationCESR-C;
  • Add wigglers for transverse cooling


1.5 T now,... 1.0T later

93% of 4p

sp/p = 0.35% @1GeV

dE/dx: 5.7%p @mip

83% of 4p

87% Kaon ID with 0.2% p fake @0.9GeV

93% of 4p

sE/E = 2% @1GeV

= 4% @100MeV

Trigger: Tracks & Showers


Latency = 2.5ms

Data Acquisition:

Event size = 25kB

Thruput < 6MB/s

85% of 4p

For p>1 GeV

  • State of art detector, well understood
  • Replace silicon strip tracker with 6 layer inner drift chamber
bepc ii double ring




Ecm=2~5.16 GeV

Luminosity~1033 cm-2s-1

(optimized at 3.68 GeV)






BEPC II — Double Ring


- 0.4-0.5 T existing BESII magnet

- 1 T Super conducting magnet


CDC: xy=50 m

MDC: xy=130 m

sp/p = 0.5% @1GeV

dE/dx=6% p @mip


T = 80 ps Barrel

100 ps Endcap


sE/E = 2.5% @1GeV

z = 0.5 cm/E

Muon ID: 9 layer RPC

Trigger:Tracks & Showers

Pipelined; Latency = 2.4ms

  • Be competitive to CLEOC
  • Almost a completely new detector

Data Acquisition:

Event size = 12kB

Thruput ~50 MB/s

physics features in c energy region1
Physics Features in -c Energy Region
  • Transition between smooth and resonances, perturbative and non-perturbative QCD
  • Rich of resonances, charmonium and charmed mesons.
  • Newtype of hadronic matterare predicted in the region, e.g. glueball and hybrid
  • Threshold characteristics, large , low multiplicity, pure initial state, S/B optimum
a typical hadronic event in cleoiii besii
A Typical Hadronic Event in CLEOIII/BESII

Hadronic events from BESII

R scan


key issues in particle physics
Key Issues in Particle Physics

Verify the SM

The test of the SM has been dominating exp. HEP for about three decades.

Establish and test strong-coupled, nonperturbative quantum field theories

Still the foremost challenge in modern physics

The effects of the strong interactions non PQCD permeate every

experimental measurement involving quarks and are an obstacle in

almost every attempt to extract precision electroweak physics from data.

Probe new physics beyond the SM

It’s of profound importance to

  • systematically study the weak interactions that mix quark and lepton flavor
  • complete understand QCD

Precision data is badly needed to enable a comprehensive mastery over

non PQCD and to calibrate and validatethe theoretical technology

ckm matrix

B decay

D decay


CKM Matrix
  • CKM, fundamental parameters in nature that reflect the flavor
  • and generation mixing, is induced by weak interaction.
  • Cannot be predicted within the SM and must be determined
  • by experiment.
  • Charm decays is a unique laboratory to determine directly Vcd
  • and Vcs, indirectly Vub and contribute to Vcb.
lattice qcd
Lattice QCD
  • LQCD is the only compete definition of QCD. It includes both perturbative and non perturbative QCD.
  • LQCD is not a model.

- The only parameters are s and the quark masses.

- Relates B/D physics to Y/ physics and to glueball

physics to …

  • Predict to ~15% accuracy for a wide range of masses (include glueball and hybrid), decay constants, form factors for many conventional hadrons.
  • The challenge for LQCD is to demonstrate reliability at the level of a few percent accuracyrequire wide range of highly precision experimental data
lqcd predictions for glueball masses
LQCD Predictions for Glueball Masses

Lowest Lying States:

Scalar 0++, M ~ 1.6 GeV

Tensor 2++, M ~2.3 GeV

Pseudoscalar, M ~ 2.5 GeV

QCD is not understood until we

understand gluonic degree of

freedom in the spectrum,

glueballs and hybrids.

the cleoc program
The CLEOC Program

Act I (2003): (3770) 3 fb-1

30M events, 6M taggedD decays

Act II (2004): ~ 4100  3 fb-1

1.5M DsDs, 0.3M taggedDs decays

Act III (2005):(3100)  1 fb-1

1 billion J/ decays

Focused data samples to collect and clear

physics goals to reach.

precision standard model tests
Precision Standard Model Tests
  • Absolute hadronic charm branching ratios with 1-2% errors
  • fD+ and fDs at ~2% level
  • Semileptonic decay form-factors (few % accuracy)

Contribute to CKM Measurements

absolute branching ratios
Absolute Branching Ratios

Decay Mode PDG2000 CLEOC

(dBr/Br %) (dBr/Br %)

D0 Kp 2.4 0.5

D+ Kpp 7.2 1.5

Dsfp 25 1.9

Set absolute scale for all heavy quark


f d and f ds
fD+ and fDs
  • LQCD can predicts fB/fD and fBs/fDs. Measure fD, fDsgive fBand fBs, thus determine Vt d and Vts
  • Similarly measure fD/fDschecks fB /fBs

CLEOC Expected Precision in Decay Constants

Decay Mode Decay Constant fDq/fDq (%)

D+ + fD2.3

Ds+ + fDs 1.7

Ds+ + fDs 1.6

semileptonic form factors

Weak physics

Strong physics

Semileptonic Form Factors

Semileptonic decay severe as excellent laboratory to study

both weak and strong interaction

e.g. D+ Kl

Decay Mode / CKM Element CKM Precision

D0 K-e+ 1.2% |Vcs| 1.6%

D0 -e+ 1.5% |Vcs| 1.7%

test of the sm and qcd in continuum
Test of the SM and QCD in Continuum
  • R scan2-5 GeV (2~3%)

Evaluating QED, a’ mHiggs,high precision test of SM, hunting for new physics beyond the SM; structures of high mass  region

  • Large hadronic events sampleat point (2-3GeV)

- Multiplicity: second binomial momentum

R2 [nch(nch-1)/nch2] = 11[1-cs(s)]/8 NLQCD

- =-ln(p/s) distribution for charged particles MLLA, LPHD

- Hadronic events shape: thrust, transverse moment distribution

pQCD, power correction

- (e+e- 2/4 /K); e+e-  /K+X;

Polarized parton density, S/U universality; quark and glue fragmentation(combine with J/ data)

  • Charmed baryons

pQCD, string fragmentation, HQE and duality

j and 2s decays
J/ and (2S) Decays

J/ decays

  • Search for new forms of matter

- Glueballs: h(1440),f0(1370), f0(1500), f(1700), fJ(2000)

- Exotic mesons: 0--, 0+-, 1-+, 2+- p1(1400), p1(1600),

  • Study of excited baryonic states (N*, *, *, *... )

(2S) decays

  • Search for missing or unconfirmed states: 1P1, c’
  • Measure hadronic branching fraction ( puzzle)
  • Measure radiative transition rate
  • Study of cJ states

Best laboratory to elucidate a tricky situation; unique

opportunity for QCD studies and new level of understanding

new study of the lepton
New Study of the  Lepton
  • Lower limit on mat sub 10 MeV level
  • Determination of m0.1 MeV
  • Precision measurement of key Br. (,0)
  • Measure Michel parameters
  • Direct search for non-SM physics
searches and new physics
Searches and New Physics
  • D0D0bar mixing
  • CP violation in , J/, (2S) decays
  • Lepton flavor violating processes

e.g. J/’, =e, , 

  • Rare decays

--X, e-G, -……. J/DX

Taking advantage of threshold production,

much high statistics and low background

why cleoc in b factory era
Why CLEOC in B Factory Era
  • Some important measurements at B’s arelimited bysystematical uncertainty
  • CLEOC enjoys threshold production, large production cross section, low multiplicity, low BG, high S/B. But limited by statistics
why besiii in cleoc era

CLEOC: 2003: y(3770) -- 3 fb-1; 30 M

2004: 4100 -- 3 fb-1; 1.5M DsDs

2005: y(3100) -- 1 fb-1; 1 Billion J/y






  • Three years CLEOC program does not cover all the interesting physics in c energy region

- 2-3 GeV, 2-3% R scan in 2-5 GeV

- physics of  and (2S)

- Charmed baryon

  • Need higher statistics for searches (glueball, exotica), rare decay, D0-D0bar mixing, CP and further improve the precision measurements.
  • New discoveries needs to be confirmed or continued. New type of matters, need high statistics to study it’s properties.
is besiii worth doing
Is BESIII Worth Doing?


if L~1033 cm-2s-1 and BESIII is competitive to CLEC, and the commissioning is not too late

Otherwise NOT really

possible side product
Possible Side Product
  • Cosmic ray experiment

e.g. low energy (E<10 GeV)  spectrum. Important for SupperK  experiment

L3CBESIII-C (cosmic exp.)

suggestions to besiii bepcii
Suggestions to BESIII/BEPCII
  • BEPCII: L~1033 cm-2s-1; BESIII compatible to CLEOC
  • Learn experiences and lessons from the other successful labs. Utilize ONLYmature technology.
  • Don’t use highest version of hardware and software.
  • Build a workable, reliable system has the highest priority. Don’t try to design fancy systems which is difficult for one to learn and use.
  • Set up an active international collaboration. A team that can committed and devoted to the project is essential
  • Select or train qualified experts in charge of each sub-system is of profound importance for the success of the project
suggestions to besiii bepcii1
Suggestions to BESIII/BEPCII
  • Prototype, R&D work should be done as early as possible
  • Additional attention should be paid to

- overall detector/ machine integration

- alignment and monitoring

- IR region

- trigger

- detector simulation, database, computing and network

- better thermo isolation in detector hall (~12-28 0C)

- better gas supply system (shorten the transportation

distance, less T)

cleoc cesrc status
  • CESR/CLEO Program Advisory Committee

Sept 28 2001 Endorsed CLEO-c

  • Proposal submission to NSF (October 15,2001)
  • Site visit on Jan/Feb 2002: Endorsed CLEO-c
  • Expect approval in Summer of 2002
  • Wiggler prototype test successfully in vertical cryostat; now being installed in its horizontal cryostat. Will be put into CESR in July
  • Start building six layers CDC
  • Cost $3.5 M
status of bepii besiii
  • Feasibility Study Report of BEPC II has been submitted to the funding agency.
  • Technical Design Report of BEPC II to be submitted soon.
  • Construction expected d to be started in 2003 and commissioning in 2007.
  • Cost $75 M (~1/3 for BESIII)
interesting schedule of cleoc besiii

CLEOC phys. run





Engineer & phys. run



Interesting Schedule of CLEOC/BESIII


Wisely seizes the great opportunity; perfectly fills the gas in the

frontier of weak and strong interactions


Nature extension. Will be a unique frontier of c physics for a

decade after CLEOC.

typical dada samples proposed
Additional Data for other physic topics

Charm baryons at threshold, e.g.

+- pairs at threshold

R scan in 2-5 GeV; large hadronic event sample in 2-3 GeV

Typical Dada Samples Proposed
  • Physics in tau-charm energy region is sill very rich in the B’s era.
  • CLEOC/CESRC, a smartdecision that seizes great physics opportunities, is opening a new era of understanding weak and strong interaction.
  • BESIII/BEPCII, an nature extension of the only high energy physics base in China, will continue BESII and CLEOC’s mission to deepen the understanding of weak and strong physics, play a unique role in the precision test of SM, QCD and search for new physics in c sector.
tanks to
Tanks to

Maury and CLEOC collaboration for the

Information about CERSC/CLEOC

Weiguo Li and BES collaboration for the

information about BESIII/BEPCII

Fred for many useful discussion about BES’s