Results from BESII and Prospects at BESIII

Weiguo LI(Representing BES Collaboration)

Institute of High Energy Physics, Beijing

Sep. 3 , 2009, Beijing, China

Outline• Introduction

• Results from BESII (selected topics)

– Results on light hadron spectroscopy– R measurement– Non-DD decays and the line shape of the

hadron cross section

• Physics at BESIII • Summary

3

Linac Storage ring

BES

BSRF

Beijing Electron Positron Collider (BEPC) at IHEP

4

BES

1-2.3GeV e+ e- collisions produce charmonium states （ J/ ， (2S) ， cJ and (3770) etc.), charm mesons and lepton.

beam energy: 1.0 – 2.3(2.5) GeV

Physics goal

4

（ BEPC/BES ）

We are unique now in -charm region

In transition region between pQCD and non-pQCD.

5

From PDG

Physics at BEPC/BES

6

Study of Light hadron spectroscopy

search for non-qqbar or non-qqq states meson spectroscopy baryon spectroscopy

Study of the production and decay mechanisms of charmonium states: J/, (2S), C(1S), C{0,1,2} , C(2S), hC(1P1), (3770), etc. New Charmonium states above open charm threshold.

Precise measurement of R values

Precise measurement of CKM matrix

Search for DDbar mixing, CP violation, etc.

Physics Topics at BES

7

Study of the spectroscopy – a way of understanding the internal structure

glueball spectrum from LQCDglueball spectrum from LQCD

Y. Chen et al., PRD 73 (2006) 0145167

Motivation: Establish spectrum of light hadrons Search for non-conventional hadrons Understand how hadrons are formed Study chiral symmetry in QCD

Why at a -charm collider ? Gluon rich Larger phase space than at

higher energies Clean environment, JPC filter

Many results in BESII: ~ 50 publicationsMuch more from BESIII:100 statistics, 10 resolution

New forms of hadrons

Hadrons consist of 2 or 3 quarks ： Naive Quark Model ：

QCD predicts the new forms of hadrons:• Multi-quark states ： Number of quarks > ＝ 4

• Hybrids ： qqg ， qqqg …

• Glueballs ： gg ， ggg …

Meson （ q q ）

Baryon （ q q q ）

Multi-quark states, glueballs and hybrids have been searched for experimentally for a very long time, but none is established.

The observation of the new forms of hadronswill be a direct test of QCD. This has beenone of the important physics goals for many experiments.

Charmonium physics• What to study ?

– Production, decays, transition, spectrum

• For what ?– A lab for pQCD and non-

pQCD– Calibrate LQCD– How quarks form a

hadron ?• Why at a tau-charm collider ?

– A clean environment – Tagging possible – Abundantly produced Examples of interesting/long standing issues:

• puzzle• Missing states ?• Mixing states ?• New states above open charm thre.(X,Y,Z,…)

11

R : one of the most important and fundamental quantities in particle physics.

R -

e+

e-

+

h a d ro n s-e

e+

q-

q

f la v o rc o lo r

= Qf2

lowestorder

R measurement

Why precise R important?

Essential for precise tests

of SM.

the global fit of Higgs mass anomalous magnetic

moment from g-2

Precise measurement of CKM elements-- Test EW theory

Precise measurement of CKM elements-- Test EW theory

b

s

d

VVV

VVV

VVV

b

s

d

tbtstd

cbcscd

ubusud

'

'

' CKM matrix

Three generations of quark? Unitary matrix?

5% precision 10% precision

Expect precision < 2% at BESIII

Precision of measurement CKM matrix elements --a precise test to SM ！

New physics beyond SM?

Precision of measurement CKM matrix elements --a precise test to SM ！

New physics beyond SM?12

CKM matrix elements are fundamental SM parameters that describe the mixing of quark fields due to week interaction.

Decays constants vs LQCD

2.3 difference for fDs. Real ?BESIII may resolve this issue, reach the precision of LQCD.

CP violation is regarded as the origin of asymmetry of the matter and anti-matter.

CP violation predicted by theoretical models is not big enough to describe the asymmetry.

CP violation is observed in K and B decays, but has never been in charm sector.

CP violation and mixing CP violation and mixing

0

0

00 | | DDCP

00 DD

e+e- (3770) D0D0

At BESIII, the sensitivity of the mixing rate: 1.5 10-4

mixing : a good place to search for CP violation

In SM, the mixing is very small.

14

00 DD

15

BESII @ BEPC

VC: xy = 100 m TOF: T = 180 ps counter: r= 3 cm MDC: xy = 220 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.5 % = 7.9 mr B field: 0.4 T p/p =1.7%(1+p2) z = 3.1 cm

16

BESI: run from 1989-1998

BESII: run from 1999-2004

L ~ 51030 /cm2s at J/

Ebeam~ 1 – 2.5 GeVBESII data samples

Data BESII CLEOc

J/ 58 M --

(2S) 14 M 27 M

(3770) 33 pb-1 800 pb-1

• A structure at 2175MeV was observed in

e+e- ISR f0(980),

e+e- ISR K+K-f0(980) initial state radiation

processes

MeV201658

MeV15102175

M

Observation of a new 1-- resonance Y(2175) at BaBar

Phys. Rev. D 74 (2006) 091103(R)Phys. Rev. D 76 (2007) 012008

Y(2175)

6.2

Y(2175)

(1680)

BESII: Y(2175) in J/ f0(980)

f0(980)

Final states: , K+K-, f0(980)+-

Define , , f0(980) signal and sideband regions.

Phys. Rev. Lett., 100, 102003 (2008)

M =2.186±0.010 GeV/c2

=0.065±0.023 GeV/c2

N events= 5212

5.5

M(f0(980)) GeV/c2

0 0

4

B(J/ψ ηY(2175)B(Y(2175) φf (980))B(f (980) π π )

(3.23 0.75( ) 0.73( )) 10stat syst

A peak around 2175 MeV/c2 is observed in J/ f0(980)

20

BELLE: e+e- ISR +-

Φ(1680)Fit results:

Belle: I. Adachi et al., arXiv:0808.0006

M(Y(2175)) = 2133+69-115 MeV/c2

Γ(Y(2175))= 169+105-92 MeV/c2

M(Φ(1680)) = 1687 21 MeV/c2

Γ(Φ(1680)) = 212 29 MeV/c2

Two(+1 for third peak) coherent BW

One BW interfering with non-resonant

673 fb-1

What is Y(2175)?

Some theoretical interpretations:

A conventional state? An analog of Y(4260) ( )? An 4-quark state?

More experimental information needed.

To understand the nature of Y(2175), we are

now working on J/K*K*, , KK, …

ss

ssssgssss

BESII: Y(2175) in J/K*0K*0 ?

B(J/K*K*)=(7.70.81.4)10-4

First measured.

M(K+-)

M(K-+)K*

M()

M(K*K*)

3-body phase space

background

K*0K*0 invariant mass in J/K*0K*0

Upper limit @ 90% C.L.B(J/Y(2175))B(Y(2175)K*K*) < 2.5210-4

24

The observation of new N* peaks in

../ ccnpJ

Missing mass spectrum (GeV/c2)

N*(1440)?

N*(1520)

N*(1535)N*(1650)

N*(1675)

N*(1680)

?

npJ /

25

Phys. Rev. Lett. 97 (2006) 062001

N*(2065)BW fit yields:

2

21530

MeV/c 4012175

MeV/c 32065

M

../ ccnpJ

PWA is performed.

• well-established N*’s are fixed to PDG values.

• for N*(2065), L=1 is much worse than L=0 in the fit.

1/2+ or 3/2+ (improve log likelihood by 400)

1/2+ + 3/2+ (improve log likelihood further by 60)

BESII: PWA of 0/ ppJ

M

0

)p(M 02

M2(p0

)

Resonances used in the PWA

Comparison of data with fit results

+ : datahist.: fit

N(1440), N(1520), N(1535), N(1650), N(1675), N(1680), N(1710) are needed.

Nx(2065) exists in this channel (stat. sig. >>5σ)

The spin-parity favors 3/2+

MeV 258230 MeV, 252040 34

M

N* M(MeV/c2) (MeV/c2) JP fraction(%)

1/2+ 9.74~25.932.38~10.926.83~15.58 6.89~27.94

4.17~30.1023.0~41.8

3/2-1/2-1/2-

N(1710)

1/2+ 0.54~3.863/2+

N(1440)

1.33~3.54

N(1535)

0.92~2.10N(1650

)0.91~3.71

N(1520)

0.34~1.54

N(2065)

0.91~3.11

Br (×10-4)

431455 27

131513 34

121537 26

261650 36

291715 22

52230 88

67316 56

37127 78

39135 88

31145 510

252040 34

4495 21

Observation of charged at BESII was first found in K scattering data

However, its phase shift is much less than 180o and it cannot be filled into any nonets of ordinary mesons.

There have been hot debates on the existence of .

In recent years:

FNAL E791 found evidence of neutral in D+ K-++

CLEO D0 K-+0 data find no evidence of

FOCUS data on K+K-++ require K*0 interfere with either a constant amplitude or a broad 0+ resonance in K

BESII observed neutral in J/ K*0K KK neutral pole:

qq

24872

8173 MeV/c )45309()30841(

i

22 MeV/c 8743410 ,MeV/c 4319797 M

• CLEO reported the necessity of in

• However, no charged is needed in BABAR data. • Charged is observed at BESII in

0 K 00 KKD

The existence of charged is expected !

0*/ KKKJ s

M(K0) GeV/c2

BESII Preliminary

Different parameterizations of are tried in PWA. Consistent results on the pole of charged are obtained.

The pole position for charged is consistent with that for neutral within the error.

26430

1428 MeV/c )101288()51841(

i

K*(1410), K*(1430)

First observation of (2S)+

• This decay mode is thought to be mainly produced from the annihilation of three gluons into ss pair.

5

22)2(

10)86.025.121.3(

)()())2((

pBKBN

NSB

S

dataobs

Statistical significance ~ 5

M

M

BESII preliminary• X,Y,Z type of particles in ss system ?• Hint: Y(2175) ?• BESIII will answer these questions with help from theorists

Resonance parameter fit• Heavy charmonia parameters were fitted with the data

between 3.7–5.0GeV, taking into accounts the phase angles, interference, energy-dependent width, etc.

Phys. Lett. B660, (2008)315

Probability =31.8%

Fitting Results Comparison

Phys. Lett. B660 (2008) 315-319

35

(3770) non-DD decays

(3770) decays most copiously into DD.

(3770) is a mixture of the 13D1 and 23S1, other (2S)-like decays for (3770) are expected. (mixing angle 122o).

Many theoretical calculations estimate the partial width for (3770) +- J/. (Lipkin, Yan, Lane, Kuang, Rosner)

Kuang obtained a partial width for (3770) +- J/ in the range of 25 -113 keV. (Y.P. Kuang, PRD 65 (2002) 094024)

36

BES first reported (3770) non-DD decay

(3770) +- J/

8.48.11)/)3770(( JN

Open histogram is for e+e-, histogram in yellow is for +-

ISR todue production '

mainly

The histogram is ’ error bars are ’+’’

/Jψ ''

/' Jψ

data MC

20 times large than the data

keV )233380()/)3770((

)%09.014.034.0()/)3770((

J

JBrhep-ex/0307028PLB 605 (2005) 63

27.7 pb-1

Anomalous LineShape of [e+e-Hadrons] in energy region from 3.650 to 3.872 GeV

Phys.Rev.Lett101,102004,2008

Two data sets taken in March and December 2003

2. Significance of the interference between the two amplitudes is 3.6

1. Significances of the two amplitudes are more than 7

3. The hypothesis of (3770) amplitude +G(3900) and interference does not significantly improve the fit from the one (3770) amplitude hypothesis

A fine scan in this area at BESIII is needed!

38

Previous exps: R/R 15 % below 5 GeV

1998-1999, BESII measured 6+85 points R values in 2-5 GeV region. R/R 6 %

Phys. Rev. Lett., 88 (2002) 101802

R Measurement

• In 2003, from a dedicated (3770) scan data, the R values at 68 energy points from 3.650-3.872 GeV were measured.

• stat. error: 3-4% syst. error: 4%

Phys. Rev. Lett., 97(2006) 262001

R values at 2.6, 3.07 and 3.65 GeV measured

with the precision of about 3.5% at BESII in 2008.

The running coupling constant s(s) was determined

• In the 1990s, there was discussion of the future. The conclusion was to continue tau-charm physics with a major upgrade of the accelerator and detector (BEPCII/BESIII). Officially approved in 2003.

• The physics window is precision charm physics and the search for new physics.

– High statistics: high luminosity machine + high quality detector.

– Small systematic error: high quality detector.

BEPCII/BESIII

BEPC II Storage ringBEPC II Storage ring:: Large angle, double-ring

RFRF SR

IP

22 m

rad

2. 5m8ns

1. 5cm

0.1cm

Beam energy: 1.0-2 .3GeVLuminosity: 1×1033 cm-2s-1

Optimum energy: 1.89 GeVEnergy spread: 5.16 ×10-4

No. of bunches: 93Bunch length: 1.5 cmTotal current: 0.91 ASR mode: 0.25A @ 2.5 GeV

43

Main parameters achieved in collision mode

parameters design Achieved

BER BPREnergy (GeV) 1.89 1.89 1.89

Beam curr. (mA) 910 650 700

Bunch curr. (mA) 9.8 >10 >10

Bunch number 93 93 93

RF voltage 1.5 1.5 1.5

s @1.5MV 0.033 0.032 0.032

x*/y

* (m) 1.0/0.015 ~1.0/0.016 ~1.0/0.016

Inj. Rate (mA/min) 200 e50 e+ >200 >50

Lum. (1033cm-2s-1) 1 0.30

44

BESIII @ BEPCII BESII @ BEPC

BESIII BESII

MDC p/p = 0.5%@1GeV, dE/dx = 6% p/p =2.5%@1GeV, dE/dx = 8%

TOF 90 ps(Barrel) 180 ps (Barrel)

EMC E = 2.5% @1GeV E = 22% @1GeV

MUC 9 for barrel, 8 for endcap 3 layers for barrel

Magnet 1.0 T 0.4 T

acceptance ~ 93%

Europe (8)GSI, Germany

University of Bochum, GermanyUniversity of Giessen, Germany

KVI/University of Groningen, NetherlandINFN, Laboratri Nazionali di Frascati

University of Torino, Italy JINR, Dubna, Russia

Budker institute of Nuclear Physics Russia  

45

Others in Asia(3)Tokyo University

Seoul National Univ.Univ. of Punjab, Lahore

USA (6)University of Hawaii

University of WashingtonCarnegie Mellon University

Univ. of Minnesota University of Rochester

Indiana University

China (25)IHEP, CCAST, GUCAS ，

Univ. of Sci. and Tech. of ChinaShandong Univ., Zhejiang Univ.

Huazhong Normal Univ., Wuhan Univ.Zhengzhou Univ., Henan Normal Univ.

Peking Univ., Tsinghua Univ. ,Zhongshan Univ.,Nankai Univ.

Shanxi Univ., Sichuan UnivHunan Univ., Liaoning Univ. , Huangshan College.

Nanjing Univ., Nanjing Normal Univ.Guangxi Normal Univ., Guangxi Univ.

Hong Kong University                 Chinese Univ. of Hong Kong          

Totally 42 institutions

BESIII commissioning and data taking milestones

Mar. 2008: first full cosmic-ray eventApril 30, 2008: Move the BESIII to IPJuly 20, 2008: First e+e- collision event in BESIIINov. 2008: ~ 14M (2S) events collectedApril 14, 2009 ~100M (2S) events collectedMay 30, 2009 ~42 pb-1 at continuum collected (3.65 GeV)July 28, 2009 ~200M J/ events collected

Machine luminosityPeak Lumi. @ Nov. 2008: 1.2 1032cm-2s-1

Peak Lumi. @ May 2009: 3.21032cm-2s-1

First collision event on July 19, 2008

0

30

60

90

120

150

180

3-6 3-11 3-16 3-21 3-26 3-31 4-5 4-10 4-150

10

20

30

40

50

5-24 5-26 5-28 5-30 6-1 6-3

0

20

40

60

80

6-12 6-17 6-22 6-27 7-2 7-7 7-12 7-17 7-22 7-27

June 12 – Jul. 28

Mar. 6 – April 14 May 24 – June 2

100 M (2S) data

200 M J/ data

42 pb-1 data at 3.65 GeV

Data accumulated at BESIII

49

Statistics at BESIII at designed peak Luminosity

(assuming 107s data taking time each year)

Physics

Energy

(GeV)

Peak Luminosity

(1033 cm–2s –1)

Events/year Existing data

J/ 3.097 0.6 10×109 60×106 (BESII)

200×106 (BESIII)

3.67(?) 1.0 12×106 --

’ 3.686 1.0 3×109 27 ×106 (CLEOc)

14 ×106 (BESII)

100 ×106 (BESIII)

D 3.77 1.0 30×106 5×106 (CLEOc)

Ds 4.03 0.6 1×106 4×103 (BESI)

Ds 4.17 0.6 3×106 0.3×106 (CLEOc)

R scan 3.0-4.6 0.6(?)-1.0 -- --

Detector performance and calibration● Layer 7● Layer 22

Wire reso. Design: 130 m

dE/dx reso.: 5.80%Design ： 6-8%

CsI(Tl) energy reso. Design: 2.5%@ 1 GeV

Barrel TOF reso.: 78 psDesign ： 80-90 ps

Bhabha

EM transitions: inclusive photon spectrum

c2c1

co

c1,2 J/

c

BESIII preliminary

Some physics signals signal

Red: K*

Blue: K*

0 signal

signalBESIII preliminary

’ l+l- : signals of cJ, 0 and

1c 2c0

m

m

BESIII preliminary

(2S) cJ

BESIII preliminary

Structures in c0+-K+K- at BESIII

BESII: PRD72, 092002

BESIII preliminary

Observation of hc: E1-tagged (2S)0hc,hcc

• Select E1-photon to tag hc

• A fit of D-Gaussian signal + sideband bkg. yield:

M(hc)Inc = 3525.16±0.16±0.10 MeV

(hc)Inc = 0.89±0.57±0.23 MeV First measurement

Br(’hc )×Br(hcc )Inc =(4.69±0.48(stat)) ×10-4 ((hc) floated) =(4.69±0.29(stat)) ×10-4 ((hc) fixed at (c1))

background subtracted

Systematic errors under study

CLEO’s results (arXiv 0805.4599v1) : M(hc)Inc= 3525.35±0.23±0.15 MeV Br(’hc )×Br(hchc )Inc =(4.22±0.44±0.52) ×10-4 ((hc) fixed at (c1) ~ 0.9MeVCLEOc: Combined E1-photon-tagged spectrum and exclusive analysis M(hc)avg= 3525.28±0.19±0.12 MeV Br(’hc )×Br(hchc )avg =(4.19±0.32±0.45) ×10-4

BESIII preliminary

BESIII preliminary

N(hc)= 2540±261 2/d.o.f = 39.5/41.0

BESIII preliminary

Observation of hc : Inclusive (2S)0hc

• Select inclusive 0

• A fit of D-Gaussian signal + 4th Poly. bkg yield N(hc) = 9233±935, 2/d.o.f = 38.8/38.0

• Combined inclusive and E1-photon-tagged spectrum Br(’hc ) =(8.42±1.29(stat)) ×10-4 (First measurement)

Br(hcc) =(55.7±6.3(stat))% First measurement

57

background subtracted

Inclusive recoil mass spectrum

Systematic errors under study

BESIII preliminary

BESIII preliminary

BR (10-3) c0 c2

00 BESIII 3.25±0.03(stat) 0.86±0.02(stat)

PDG 2. 43±0.20 0.71±0.08

CLEO-c 2.94±0.07±0.35 0.68±0.03±0.08

BESIII 3.1±0.1(stat) 0.59±0.05(stat)

PDG 2.4±0.4 <0.5

CLEO-c 3.18±0.13±0.35 0.51±0.05±0.06 CLEO-c arxiv:0811.0586

Study of (2S)→ 00 , ( → , 0 → )

• Interesting channels for glueball searches

• Based on 110M (2S)

• BK study from 100M inclusive MC sample

and 42pb-1 continuum sample

• Unbinned Maximum Likelihood fit:

– Signal: PDF from MC signal

– Background: 2nd order Poly.

2S)00

Nc0 16645±175 Nc2 4149±82

2S)

Nc0 1541±56 Nc2 291±23

Confirmation of the BESII observation: pp threshold enhancement in J/ decays

PRL 91 (2003) 022001

/J pp

BES III preliminary

(2S)→ J/

M=1864.6 ± 5.3MeV/c2

< 33 MeV/c2 (90% CL)

M=1859 MeV/c2

< 30 MeV/c2 (90% CL)

+3 +510 25

0.3

/J pp BES II

M(pp)-2mp (GeV)

Confirmation of BESII observation: No pp threshold enhancement in (2S) decays

No significant narrow enhancement near threshold(~2 if fitted with X(1860))

Mpp (GeV)

BES III preliminary

PRL 99 (2007) 011802

BES II

No enhancement in ’ decays

pp pp

In fact, no enhancement in ’ decays or in the process of J/ pp shows that FSI unlikely

Study of cJ VV (V= , )

0c

1c2c

0c1c

2ccJ

cJ • First measurement of c1 and

• First measurement of cJ

cJ

0c1c

2c

BESIII preliminary

M()

M()

M()

BESII data 58M J/ BESIII MC 58M J/

' '

X(1835)

> 10

X(1835) 6

MC simulation: X(1835) at BESIII ,' ,'/J

,' ,'/J

BESII data 58M J/ BESIII MC 58M J/

'

X(1835)

> 10

X(1835) 5.1

'

• assuming 2.5 BESII J/ events

• J/a0(980), a2(1320), (1390), a2(1700) are included. the spin-parity of each component as well as the interference between them are considered.

• background included (estimated from sideband, about 10%)

• a full PWA is performed.

Search for 1-+ in J/00 (MC)

Comparison of generated data and PWA projections

M(0) GeV/c2

M(0) GeV/c2

input output input output input output

a2(1320) 1318 13202 107 112± 4 20.84 19.49± 0.80

1(1400) 1376 1380 8 360 376±16 14.57 14.66± 1.30

Mass(MeV/c2) Width(MeV/c2)

Fraction(%)

Input/output check

Data taking plan in the near future

(3770) scan to study non-DD decay, the precise energy measurement system should be ready

Taking larger data sample of J/ , and (2S)

Taking large data sample at (3770)

nb 80025.028.9Born)3770( .

Born

obsDD

Born

BornDDDD

σgN

NDDBF

)3770(IIBES)3770(prd

(3770)

prd

))3770((

014.0764.0IIBES g

)%5.31.11.36())3770(( DDBF )%9.33.15.50())3770(( 00 DDBF

)%9.57.16.86())3770(( DDBF

)%9.57.14.13())3770(( DDnonBF

))3770(( & DDBFR

Assuming that there are interference between the two amplitudes

With BES previously measured cross sections for DD production.

Phys. Lett. B 641, 145(2006)

00DD

DD

Inclusive hadrons

Branching fractions

)%8.27.39.36())3770(( DDBF

)%3.27.47.46())3770(( 00 DDBF

)%2.43.76.83())3770(( DDBF

)%2.43.74.16())3770(( DDnonBF

Phys.Rev.Lett.97:

121801(2006)))3770(( DDBF

Mainly due to vacuum polarization corrections

MeV 0.83772.2M (3770)

MeV 2.426.9tot(3770)

eV 28251ee(3770)

Resonance parameters

Better than PDG world average

First observed this effects!

keV 258331tot(2S)

keV 0.110.042.33ee(2S)

CLEO (3770)

non-DDbar decays

+ c0

’’XJ/:

missing event energy (GeV) after finding +, -, J/(ll)

e+e-’ (J/+-)’’

J/+-

’’cJ:

cJ

J/

:

cJ

had

rons

:

((3770)hadrons)(6.5 0.1 +0.4

-0.3 ) nb

((3770)DD)(6.39 0.10 +0.17

-0.08 )nb

( (3770)non-DD)(-0.01 0.12 +0.40

-0.33 )nbtranslates into BR UL

B((3770)non-DD) < 10%

Exclusive channels:

Mode BR (%)

+J/ 0.1890.0200.020

00J/ 0.0800.0250.016

J/ 0.0870.0330.022

c0 0.730.070.06

c1 0.390.140.06

(3.10.60.3)10-2

other ~2

(3770)non-DD decay is very interesting ， needs results from BESIII to finally decided 。

Challenges in BESIII Physics Analyses

personal view

New ideas in BESIII Physics, although

There is a nice guidance for BESIII

Physics (yellow book), new ideas are

very important. Theorists – experimentalists

To collect large data samples with good data quality

There are some difficult problems to solve:

-- Machine backgrounds and noise: adding more masks;

adjusting detector setting (MDC); solving problems when

they occur.

arXiv: 0809.1869

-- Gradually increase the machine luminosity and stability of the machine, last time the luminosity is 20%, 10% of the designed luminosity at (2S), J/, still a long way to reach designed luminosity,

More currents(vacuum, RF power?);

Better tuning of the machine, …;

Hardware improvement if needed;

Beam energy is estimated to reach 2.3 GeV, but it needs to be tested;

Develop physics analysis tools: partial wave analysis, Dalitz plot analysis, etc.

Improve software and understand the detector: calibration, alignment, simulation, data/MC comparison. It is important to reduce the systematic errors, as for some physics, the systematic errors are already dominant.

Prospects: a bright future Usually each year, BESIII should take data 5-6 months, SR 3-4 months,• BESIII will resume data taking after summer shutdown, ~5 months until next summer

• Possible plans: – 500-1000 M J/ events (2-4 months)– 500-1000 M (2S) (2-4 months)– 2fb-1 (3770) (4 months)– Lineshape scan of (3770) (2 weeks)

• Expecting new and exciting results from new data

To be decided in Nov. 2009

Thanks

mixing & strong phase• Tag one D0 in CP eigenstate, the

other side is a mixture of and Rate B1B2(1+2rcos)

• A global fit with inputs of – Yield of each channel(ST & DT)– BG from MC + PDG– Results from Babar, Belle, CDF,

E791, Focus & CLEO

• Output:

DDCLEO

0 0

2 2, , , cos , , sin , 9 BFsD D

y r x x N

0D0D

Hadronic Single Tags

D. M. Asner and W.M. Sun, Phys. Rev. D73, 034024 (‘06) and Phys. Rev. D77, 019901 (E) (‘08);

W. M. Sun, NIMA 556, 326 (’06)

Quantum correlation

DDbar mixing described by:x=M/yRM=(x2+y2Actually measuredx’ = xcos+ ysiny’ = -xsin + y cos

Phys. Rev. Lett. 100, 221801 (’08)

Phys. Rev. D78, 012001 (’08)

CLEO

11 + 922

12 11

• Based on 281 pb-1 at (3770)• Still limited by statistics • Future:

– More statistics: 818 pb-1 in hands– More semileptonic channels to better

constrain y• At BESIII:

– will collect ~15 fb-1 in a few years – Muon ID: better in channels such as

K

First determination of cos

mixing: where are we now ?• We know there is a mixing, but• Consistent with SM ?

– Quark level: much too small – Hadron level: not calculable yet

• Consistent with NP ?– Yes, with many models

• What’s next ?– Integrate all flavor physics

results – Correlate with other mixing

results – More rare decay/CPV limits to

constrain NP models

DD

no mixing excluded at 9.8σ

http://www.slac.stanford.edu/xorg/hfag/charm

ICHEP08BESIII can provide valuable information

Search for CP violation

• CP violation in D0-D0bar mixing

• CP violation in direct decay (direct CP violation)

• CP violation from the interplay of decay and mixing (indirect CP violation)

consistent with CP conservation

http://www.slac.stanford.edu/xorg/hfag/charm

CP violation in direct decays• CPV in D and Ds decays

• CPV in Cabibbo suppressed D(s) decays

281 pb-1 PRD 76, 112001 (’07) 298 pb-1 PRL 100, 161804 (’08)

PRD 78, 072003 (’08)

No observed asymmetry, integrated over phase space: ACP = (-0.03 0.84 0.29)%Or in specific two-body amplitudes Still far away from SM expectations (< 10-3)BESIII can touch it

CLEO