Reach of future -charm efforts at BESIII Yangheng Zheng Graduate University of Chinese Academy of...
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Transcript of 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
May 5-9, 2007Y. Zheng @NTU, FPCP20083
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
May 5-9, 2007Y. Zheng @NTU, FPCP20084
Charm productions at BEPCIICharm productions at BEPCII
GeV
May 5-9, 2007Y. Zheng @NTU, FPCP20085
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
May 5-9, 2007Y. Zheng @NTU, FPCP20086
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
May 5-9, 2007Y. Zheng @NTU, FPCP20087
DAQ + Trigger ( MDC + EMC + TOF+MUC )
Cosmic Ray eventCosmic Ray event
Testing period:
Jan. ~ Mar., 2008
May 5-9, 2007Y. Zheng @NTU, FPCP20088
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.
May 5-9, 2007Y. Zheng @NTU, FPCP20089
BESIII has been moved to IP (April)!BESIII has been moved to IP (April)!
May 5-9, 2007Y. Zheng @NTU, FPCP200810
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.
May 5-9, 2007Y. Zheng @NTU, FPCP200811
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;
May 5-9, 2007Y. Zheng @NTU, FPCP200812
Physics potential at BES-IIIPhysics potential at BES-IIIYi-Fang Wang Charm 2007
May 5-9, 2007Y. Zheng @NTU, FPCP200813
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
May 5-9, 2007Y. Zheng @NTU, FPCP200814
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.
May 5-9, 2007Y. Zheng @NTU, FPCP200815
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)
May 5-9, 2007Y. Zheng @NTU, FPCP200816
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)
May 5-9, 2007Y. Zheng @NTU, FPCP200817
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
May 5-9, 2007Y. Zheng @NTU, FPCP200818
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
May 5-9, 2007Y. Zheng @NTU, FPCP200819
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
May 5-9, 2007Y. Zheng @NTU, FPCP200820
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
May 5-9, 2007Y. Zheng @NTU, FPCP200821
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
May 5-9, 2007Y. Zheng @NTU, FPCP200822
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
May 5-9, 2007Y. Zheng @NTU, FPCP200823
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
May 5-9, 2007Y. Zheng @NTU, FPCP200826
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.
May 5-9, 2007Y. Zheng @NTU, FPCP200827
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
May 5-9, 2007Y. Zheng @NTU, FPCP200828
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
May 5-9, 2007Y. Zheng @NTU, FPCP200829
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
May 5-9, 2007Y. Zheng @NTU, FPCP200830
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)
May 5-9, 2007Y. Zheng @NTU, FPCP200831
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
May 5-9, 2007Y. Zheng @NTU, FPCP200832
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
May 5-9, 2007Y. Zheng @NTU, FPCP200833
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