reach of future -charm efforts at besiii yangheng zheng graduate university of chinese academy of...

Reach of future Reach of future -charm efforts -charm efforts at BESIIIat BESIII

Yangheng ZhengGraduate University of

Chinese Academy of SciencesFPCP2008 @ NTU

May 5 - 9, 2008

May 5-9, 2007Y. Zheng @NTU, FPCP20082

OutlineOutline

Status of BESIII -charm physics potentials Summary


BEPC II Storage ringBEPC II Storage ringRFRF SR

IP22

mra

d

2. 5m8ns

1. 5cm

0.1cm

Beam energy: 1.0-2.3 GeVLuminosity: 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 A


Charm productions at BEPCIICharm productions at BEPCII

GeV


The BESIII DetectorThe BESIII Detector

Be beam pipe

SC magnet, 1TMagnet yoke

MDC, 130 m

CsI(Tl) calorimeter, 2.5 %@ 1 GeV

TOF, 100ps

RPC


Japan (1)

Tokyo University

USA (7)

University of Hawaii

University of Washington

Carnegie Mellon University Univ. of Florida

Univ. of Minnesota Rensselaer Polytechnic Institute

University of Rochester China (24)

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.

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

Hong Kong University

Chinese Univ. of Hong Kong

Europe (5)

GSI, Germany

University of Bochum, Germany

University of Giessen, Germany

JINR, Dubna, Russia

Budker institute of Nuclear Physics Russia

“Spectators”: four institutes from Italy

Totally 37 institutions now

BESIII collaborationBESIII collaboration


DAQ + Trigger （ MDC ＋ EMC ＋ TOF+MUC ）

Cosmic Ray eventCosmic Ray event

Testing period:

Jan. ~ Mar., 2008


Cosmic ray test status Cosmic ray test status

All systems work TOF resolution: 110ps achieved MDC resolution: 130m achieved

Some problems found and fixed (wrong cabling, Electronics, noisy channels, bad PMT/FED board, etc )

Online data taking is stable and robust, Most of trigger conditions tested. 2nd round of cosmic ray test has started

on May 8.


BESIII has been moved to IP (April)!BESIII has been moved to IP (April)!


BESIII StatusBESIII Status The construction, testing and field

measurement of detector super-conducting magnet completed, field measured at 1 tesla and 0.9 tesla.

Finish the installation of all the detector components, MDC, Barrel and endcap TOF, barrel and endcap EMC, all muon chambers, Be beam-pipe.

Commissioned sub-detectors with DAQ, Trigger, and Slow control passed the cosmic ray test.

Software and physics preparation in good shape.


Next StepsNext Steps

Commissioning machine and detector together in June 2008;

BESIII yellow book, (specifies the physics goals and potentials, detailed study of certain channels) will be published around June.

To pass the government review in end of 2008, Lum. ~ 3 x 1032cm-2s-1 ; Detector meet certain performances;


Physics potential at BES-IIIPhysics potential at BES-IIIYi-Fang Wang Charm 2007


Charm meson productionCharm meson production

Threshold production at 3.773, 4.03, 4.17 GeV

Double Tag techniques:

(partial-)reconstruct both D mesons Charm events at threshold are very

clean Ratio of signal to background is optimum Lots of systematic uncertainties cancellation

while applying double tag method

*, ,s s s se e DD D D D D


DD Pairs at Different Experiments Pairs at Different Experiments

0

200

400

600

800

BESII CLEO-c BES-III BaBar Belle

0.2 M 5 M~120M

500M

700M

(3770) peak (4S) PeakBackground free High statistics

~120 M is expected at BES-III with 4 years’ luminosity. 5 M is expected at CLEO-c until 2008.


ffD+ D+ and challenge of QCDand challenge of QCD

BES-III reaches 2% with 20 fb1 data @ psi(3770).

7.6%

2.0%

2.0%

CLEO-c: 281 pb-1

PRL 100, 062002(2008)


ffDs Ds –challenge LQCD–challenge LQCD

4.0 sigma discrepancy between LQCD and experimental determination in the SM.

H.B.Li ,J.H.Zou arXiv:0804.1822

1.2%

3.2%

See Hewett [hep-ph/9505246] & Hou, PRD 48, 2342 (1993).

1.0%

CLEO-c, Belle and BaBar:

2.0% 276±6

PRL 100, 062002(2008)


DD mixing at mixing at BB-factory:-factory: D D→→KKππ f = K-π+ , f = K+π-

( ) ( )(DCS)(DCS) 1 1

, , 1, 1(CF) 1 1(CF)

f fi iD D

f f

M D

D M

pAA A

A

qAR e R e

pA qA A

WS

RS

δ: strong phase diff. (assume CPV via weak phase only),

φ: weak phase

, , 0, 0, 0K D MK

q p A A A A

2

WS

22

4t

D D

x ye R Rt y t t

cos sin

cos sin

x x y

y y x

If CP is conserved:

For CPV case: fit two WS distribution separately


What about Charm factory?What about Charm factory?

Mixing at threshold Bad news: no time-dependent information Good news: Quantum coherence, CP tags

The coherence of two initial D allows simple methods to measure DDbar mixing, strong phase and CP violation

In 20fb-1 (3770) data, we can get > 4.5x105 CP+ tags and > 3.6x105 CP- tags > 10,000 CP+ vs K double tags and >

10,000 CP- vs K double tags


Mixing ParametersMixing Parameters

22mix yx

2

1R

KK

KK

cosysinxy

sinycosxx

)CP()CP(

)CP()CP(yCP

sinxcosyyCP

Mixing rate

Strong phase difference of CF decayand DCS decay, important to measure

CP eigenstate lifetime difference

CP violation phase

2222qpqp

sinx2 CP violation in mixing/decay interference

CPV in mixing

If CP is conserved, =0, =0, yCP=y


Sensitivities (20 fbSensitivities (20 fb-1-1)) Mixing parameters =(x2+y2)/2 < 10-4 in

K and Ke channels Probe y: ΔyCP < 0.7%,

ΔcosK < 0.06

CP Violation ΔACP~10-3 in D+ decays (direct

CPV),

contributions to 3/ errors: <2o (CLEO-c: ~5o,see Sheldon’s talk)

0

0

. .

. .M

D W SR

D R S

BESIII


3109 (2S) events /year at BES-III

Charmonium physics in Charmonium physics in (2S) decays(2S) decays

Understand charmonium spectroscopy and charmonium decay dynamics Hadronic transition (54%) Radiative transition (28%) Study of spin-singlets (hc, c, c’) Hadronic decays (15%) Leptonic decay (2%) Radiative decays (2%)

Search for rare decays and new phenomena


58M J/ data

5.0

at BESIIIat BESII

>10

M(’) GeV/c2M(’) GeV/c2

3109 J/psi events (50 times of BESII) 2 years’ data taking

' ,'/JX(1835) at BESIII via

ExampleExample


SummarySummary

Commissioning of the BESIII detector went smoothly. (Physics data will be taken on early July)

Software and physics analysis preparation is in good shape.

Physics potentials can reach: light hadron, charmonium spectroscopy; open charm physics; energy scan; tau physics, etc.

謝謝！謝謝！

Backup slidesBackup slides


Be beam pipe Be beam pipe

two Be cylinders (0.8 mm and 0.5 mm thick, 0.8mm gap), cold by paraffine-1

14.6 m gold at the inner surface. All will be welded together in a couple

of days, should be ready for installation in the BESIII before March 20.


Drift chamberDrift chamber To measure the momentum of charged particles Design spec.: Single wire reso. dE/dx reso.

CLEO: ~110m, 5.7%

Babar: ~110m, 6.2%

Belle: ~130m, 5.7%

BESIII ~120m 6 %

Rin = 63mm; Rout = 810mm; length = 2400 mm

7000 Signal wires: 25(3% Rhenium) m gold-plated tungsten 22000 Field wires: 110 m Al Gas: He + C3H8 (60/40)

Momentum resolution@1GeV:

0.5%

%37.0%32.0 t

P

Pt


BESIII CsI(Tl) crystal calorimeterBESIII CsI(Tl) crystal calorimeter To measure the energy of electromagnetic particles Barrel: 5280 crystals ， Endcap: 960 crystals Crystal: (5.2x 5.2 – 6.4 x 6.4) x 28cm3 Readout: ~13000 Photodiodes, 1cm2cm, Energy range ： 20MeV – 2 GeV position resolution: 6 mm@1GeV Tiled angle: theta ~ 1-3o, phi ~ 1.5o

Babar: 2.67% @1GeV

BELLE: 2.2% @1GeV

CLEO: 2.2% @1GeV

BESIII: 2.5%@1GeV


PID: Time-Of-Flight countersPID: Time-Of-Flight counters Double layers at barrel of 88 counters/layer, readout at both ends, endcap each has 48 counters, readout at the inner end.

Barrel TOF Endcap

TOF

High quality plastic scintillator: 2.4 m long, 5cm thick


CP eigenstate TagsCP eigenstate Tags

CP + K+K (3.89X10-3 ) +(1.38X10-3 ) Ks 00

00(8.4X10-4) KSKS (7.1X10-4) 00(3.2x10-3)

CP – KS0(0.012) Ks (3.9X10-3) KS ' (0.0094) KS0 (0.0078) Ks (0.012) KS (4.7X10-3)

In 20fb-1 (3770) data, we can get> 4.5x105 CP+ tags and > 3.6x105 CP tags

With large sample of CP tags, we may improve the measurementsof strong phase, probe the direct CP, and other mixing parameters

Dalitz Analysis

For Ks modes: CPV effect of Ks

need to be considered!

(Prof. Xing/Zhizhong’s suggestion)


RRmixmix measurements @3.773 measurements @3.773

Golden channel D0K Semileptonic

channel Ke, K, etc

2 2

2M

x yR

0

0

. .

. .M

D W SR

D R S

Double tag measurements. Number ofR.S. tags at BESIII are expected to be104-105, the sensitivities of Rmix will @ 10-4—10-5

2-body identical final states are Required in both D hadronic decays

experimenttheory


Strong Phase measurement Strong Phase measurement

cosr2)CP()CP(

)CP()CP(A

Nr2

1cos

In 20fb-1 (3770) data, we can get> 10,000 CP+ vs K double tags> 10,000 CP- vs K double tagsThe precision of cos < 0.06 level is expected at BESIII,

Be helpful to improve the precision of /3 measurement


yyCPCP measurements at BESIII measurements at BESIII

sinxcosy)CP()CP(

)CP()CP(yCP

sinxcosy)CPD()CPD(

)CPD()CPD(A

00

00

sinxAcosyyCP

Two interesting case with semileptonic tag + CP tags

CPV in Mixing is small, Δ=0

In 20fb-1 (3770) data, 10,000 SL+CP(+) tags 10,000 SL+CP(-) tags

ΔyCP and ΔAΓ~ 1% level

Applying the inclusive semileptonic tag Can improve the measurements

reach of future -charm efforts at besiii yangheng zheng graduate university of chinese academy of...

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