Pentaquark Search at Hermes

1
Extracting Physics From BESIII Experiment
Yajun Mao (School of Physics, PKU) for BESIII
Collaboration
Oct 31,2006
2
Outline
Introduction
Some Physics Reach _at_ BESIII
BESIII Physics Book
Preparation of Physics Analysis
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Why BEPCII/BESIII?
High precision experimenthigher lumi/statistics
better detector gt higher precision for
rare process
Test SM and search for new Physics
CKM elements
J/Y decay Lepton University
D meson
decay Basic QCD Parameters Light hadron
spectroscopy Charmonium Physics
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Events Expected at BESIII
Physics Channel Energy (GeV) Luminosity (1033 cm2s 1) Events/year
J/y 3.097 0.6 1.01010
t 3.67 1.0 1.2107
y 3.686 1.0 3.0 109
D 3.77 1.0 2.5107
Ds 4.03 0.6 1.0106
Ds 4.14 0.6 2.0106
D production cross section is taken as 5 nb
5
Hints for New Spectroscopy-Challenge QCD
X(3872)
X(3940)
Z(3930)
Y(3940)
B decays
J/yccbar
gg
B decay
Belle
2003
2004
Partial Wave Analysis will be the KEY tool in
the study of spectroscopy, some of Key issues
should be solved in the future.
DsJ(2317)
2005
DsJ(2458)
Y(4260)
ISR
BaBar
Continuum
Glueball, hybrid or exotic search in J/y (10?109)
_at_ BESIII f0(600)

f0(980)

f0(1370)
J/y ? (g, ?, ?,
?) f0(1500) and also Tensor candidates
f0(1710)
and Many threshold
enhancements
f0(1790) J/y ? ppbar X ? probe excited and
exotic baryon states by B. Zou
J/?? g pp- ?
J/? ? g pp
BESII
Are they the same particle?
X(1860)
X(1835)
3 5 -10 -25
M1859 MeV/c2 G lt 30 MeV/c2 (90 CL)
X(1835) mass is consistent with the mass of the
S-wave resonance X(1860) indicated by the pp
mass threshold enhancement.
A detail angular analysis will definitely tell us
the JPC of X(1835) at BESIII
35 ?104 events in J/? ? g
pp (? 50)
24 ?104 events in J/?? g pp- ? (? 12)
10 billion J/?
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Scan of the resonance _at_ 3.7 - 4.6 GeV to probe
spectroscopy
Test QCD _at_ 3.7 - 4.6 GeV
Search for exotic ccbar, Y(4260)
Probe gluon enhanced hidden ccbar states
DD Enhancement at DD threshold
Plateau in DD
Very little DD
A detail plan to take data _at_ BESIII should be
made based on the study of RD in Physics book.
CLEO-c Preliminary
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Dalitz Analysis at BESIII

• K-pp0, Kspp- vs CP tags, measure strong phase
  of K?, Kp
• K-pp0, Kspp- vs flavor tags, measure Br of DCSD
• Kspp-, p-pp0 vs CP tags, search for CP
  Violation (via same sign CP Tags)
• Strong phase measurement Measurements of g/f3
  in B?D()K()
• CP asymmetries across Dalitz Plots
• Kspp-, p-pp0 vs flavor tags
• D ? K-K p

Light spectroscopy in D Dalitz analysis (Kp)
s-wave, (pp) s-wave, many isoscalars M.
Penningtons talk at Charm2006
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Charmonium below open charm _at_ BESIII
What can we do with 3 billion y(2S)?
?c,0,1,2 sample useful to understand the decay
dynamics of ccbar and light hadron with same
JPC! Q. Zhao, hep-ph/0508086
Y(2S) ? pp-J/y (31) really pure J/y sample
a complementary of J/y peak data!
1977
1974
2002
1975
2004
?c? in y(2S) ?g KSKp y(2S) ? g pp-?C
with untagged gamma M. Voloshin hep-ph/0206240
B(?C(2S) ? pp-?C ) 5-10
2S 1D mixing rp puzzle J. Rosner PRD 64
(094002) 2001 P. Wang et al PRD70(114014)2004
Non-DD decay of y(3770) N. Achasov
hep-ph/0505146 The productions of D0D0, DD-
M. Voloshin hep-ph/0402171
Detail study of hC at BESIII
1980
1974
?C(1S) sample from J/y ? g ?C(1S) used to study
the light spectrum
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Charmonium Decays of ?(4040), ?(4160), and Y(4260)
Scan Run will be crucial at BES-III ECM
3970-4260 GeV
From the current experimental indication!
CLEO-c Preliminary Ron Poling talk at Charm2006
CLEO-c PRL 96, 162003 (2006)
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BES III Charm Mixing (1)
Quantum Correlations in D0D0 decays from the
?(3770) allow measurement of strong phases and
mixing parameters from BESIII Coherence
simplifies study DCSD interfere away so not a
background Unmixed D0? K-p D0? Kp-
mixing D0? K-p D0? D0 ?K-p
D0D0 ?(Kev Kev)

• BESIII PID system
• dE/dx, resolution (6-7)
• Two layer barrel TOF, time resolution 100ps,
  83 solid angle coverage
• 1 layer endcap TOF, 110ps
• Selection efficiency is gt20 with a K/p double
  mis-identification rate at lt 10-4 level

• Two missing neutrinos in events
• Electron PID can suppress background
• The selection efficiency is similar as the Kp
  channel
• Background level is also negligible while running
  a small MC data sample (1 of 20fb-1). More
  detail study is needed.

With 20fb-1(4-5 years running) at ?(3770) peak
RM lt10-4
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BES III Charm Mixing (2)
Be careful ee- ? DD( ng)(mp) no resonant
contribution, TQCA will be lost!
BESIII
D0 Momenta from CLEO-c Preliminary
Evidence for multibody (MB) events, e.g.
ee-?DD?
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Estimated uncertainties (stat.) of Mixing
parameters using TQCA
From PRD 73 034024 (2006) by Asner and Sun
Using single and double CP/flavor tags
complicated analyses
From Kanglin He
Have to identify C1 of gD0D0bar and gD0D0barp0
from DDbar and DDbar decays
parameter value CLEO-c (3x106D0D0b) CLEO-c (3x106D0D0b) BESIII(20fb-1) BESIII(20fb-1)
parameter value C-1 C1 C-1 C1
y 0 0.015 0.007 0.003 0.002
x2 0 0.0006 0.0003 0.00013 0.0001
cosdKp 1 0.15 0.13 0.035 0.04
xsindKp 0 - 0.010 - 0.003
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CP eigenstate Tags

• CP
• KK- (3.89X10-3 )
• pp- (1.38X10-3 )
• Ks p0p0
• p0p0 (8.4X10-4)
• KSKS (7.1X10-4)
• ?0 p0 (3.2x10-3)

• CP
• KSp0(0.012)
• Ks? (3.9X10-3)
• KS ? (0.0094)
• KS?0 (0.0078)
• Ks? (0.012)
• KSf (4.7X10-3)

In 20fb-1 ?(3770) data, we can get gt 4.5x105 CP
tags and gt 3.6x105 CP- tags
With large sample of CP tags, we will definitely
improve the measurements of strong phase, probe
the direct CP, and other mixing parameters
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CP Violation at ?(3770) at BESIII

• CP violating asymmetries can be measured by
  searching for events with two CP odd or two CP
  even final states

pp-, KK-, p0 p0, Ksp0 ,
ACP sensitivity 10-2 - 10-3
K K vs pp
Beam constraint Mass
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Leptonic and Semileptonic decays at BESIII
BESIII Integrate Lumi. 20fb-1 DDbar MC
simulation
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BESIII Physics Yellow Book
Part One The BES-III Experiment and its
Physics Conveners Jian-Ping
Ma and Ya-Jun Mao Part Two ee- collision at
BEPC-II Conveners Xiao-Yuan
Li and Yuan-Ning Gao Part Three Light Hadron
Physics Conveners Bing-Song
Zou and Xiao-Yan Shen Part Four Charmonium
Physics Conveners
Cong-Feng Qiao and Chang-Zheng Yuan Part Five
Charm Physics Conveners
Zhi-Zhong Xing and Hai-Bo Li Part Six Tau
Physics Conveners Toni
Pich and Chang-Zheng Yuan Part Seven Comparison
with other facilities and future prospects
Conveners Cai-Dian Lu and Shan Jin
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Chapters of the Yellow Book
Part One The BESIII experiment and its physics
Jian-Ping Ma and Ya-Jun Mao Chapter 1.
Physics goal of BESIII
Jian-Ping Ma Chapter 2. The BESIII detector
Ya-Jun Mao
Chapter 3. Offline Software
Ya-Jun Mao and Wei-Dong Li
Chapter 4 Analysis tools
Kang-Lin He Part Two ee-
collision at BEPC-II
Yuan-Ning Gao Chapter 5. Physics Processes
Ping Wang and
Da-Hua Zhang Chapter 6. Hadron Production
and Fregmentation Hai-Ming Hu Chapter 7.
R values
Xiao-Yuan Li Chapter 8. QCD
studies at sqrt(s) 2-5 GeV H.M. Hu
and Y.N. Gao Chapter 9. Production cross
section of DD and DsDs Kang-Lin He
Chapter 10. Measurements of Parameters of
Charmonium Resonances

Yuan-Ning Gao and Gang Rong Part
Three Light hadron physics Bing-Song
Zou and Xiao-Yan Shen Chapter 11. Hadron
spectroscopy status and prediction Q. Zhao, C.
Liu and Y.Chen Chapter 12. Meson spectrum
Qiang Zhao
Chapter 13. Baryon spectrum
Bing-Song Zou Chapter
14. Glueball searches
Qiang Zhao Chapter 15. Hybrid,
Multi-Quark and Molecule candidate searches
Shi-Lin Zhu
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Chapters of the Yellow Book
Chapter 16. Two-photon physics
Bing-Song Zou and Hai-Bo Li
Chapter 17. Soft pions and a0-f0 mixing
Han-Qing Zheng Part Four Charmonium
Physics Cong-Feng Qiao and
Chang-Zheng Yuan Chapter 18. Charmonium
transition C.Z. Yuan Chapter 19.
Leptonic decays P.Wang Chapter
20. Radiative decays Cong-Feng Qiao
and C.Z.Yuan Chapter 21. Hadronic decays
X.H. Mo, C.Z.Yuan Chapter 22.
Rare and forbidden Charmonium Decays X-M Zhang,
J-P Ma, Hai-Bo LI Chapter 23. Charmonium
spectroscopy close to open charm threshold
Chapter 24. Exotic decays of Psi(4030),
Psi(4160) and Psi(4415) Steve Olsen Part Five
Charm Physics Zhi-Zhong
Xing and Hai-Bo Li Chapter 25. Leptonic D
(Ds) Decays Ya-Dong Yang and Gang Rong
Chapter 26. Semileptonic D(Ds) decays and CKM
matrix M-Z Yang and G. Rong Chapter 27
Hadronic D(Ds) decays
Yue-Liang Wu and Kang-Lin He Chapter
28. Charm baryon production and decays H. Y.
Chen Chapter 29. DDbar mixing and CP
violation D. Asner, I. Bigi, K. He, H.
Li, Z-Z. Xing Chapter 30. Rare and forbidden
charm decays Ya-Dong Yang and Hai-Bo Li
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Chapters of the Yellow Book
Part Six Tau Physics
Toni Pich and Chang-Zheng Yuan Chapter 31.
Tau mass near threshold Chapter 32. Hadronic
tau decays Chapter 33. Leptonic and
semileptonic tau decays Chapter 34. Search
for CP violation in tau decays Part Seven
Comparison with other facilities and future
prospects
Cai-Dian Lu and
Shan Jin Chapter 35. Tau-Charm physics at B
factories Alex Bondar and Steve Olsen
Chapter 36. Opportunities of Tau-Charm physics at
Super-B factories
D.
Asner and I. Bigi Chapter 37. Do we need a
super-charm factories D. Asner and Alex Bondar
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Status of The Book

• Proposed in Jun, 2005
• 1st meeting Mar 6, 2006, in XiamenThe
  primary content lists
• were approved Some examples were shown on
  the meeting
• Latex Style was fixed
• 2nd meeting Apr10, 2006, IHEP, in Beijing
  The editorial board
• was ratified and editor-in-chiefs were
  approved The structures of
• the book were adjusted Conveners for each
  part and each chapter.
• 3rd meeting May 10, 2006, IHEP, in Beijing
  Most of the conveners
• joined the meeting, a detailed plan was
  discussed.
• Convener of each part/chapter presented their
  own schedule.
• 4th meeting Aug 5, 2006, in Beijing, progress
  review of the book
• 5th meeting Nov. 4, 2006, in Beijing, second
  review of the progress
• 6th meeting Dec, 2006, The Proofread

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Analysis Preparation
Physics Analysis
Real Collision
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Overview of BESIII Offline Software
Reconstruction
Physics Analysis
Physics Analysis
Detector Simulation
Event Display
Event Generator
GEANT4
GAUDI
ROOT
BOSS
BOOST
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Software Environment

• Underlying framework
• GAUDI (originally developed by LHCb)
• Simulation
• GEANT4
• Other external LIBs
• CERNLIB, CLHEP, ROOT, AIDA, XercesC, GDML
• Database PGSQL/MySQL
• Software configuration management
• CMT and CVS
• Computer language C (BESII legacy code written
  in Fortran )
• Operation system
• Redhat 7.3/gcc3.2 (now), SLC3/ gcc3.2.3 (in the
  future)
• Reused code from Belle, BaBar, ATLAS,GLAST

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Main Drift Chamber Software

• Simulation
• Stereo cells are described by G4TwistTube.
• Digitization is based on parameters from test
  beam data.
• The calibration algorithm contains correction to
• X-T relation, spatial resolution,T0, wire
  position, time walk.
• Reconstruction algorithms are TrkReco and
  MdcPatRec. For single 1 GeV muons, both of them
  obtain
• Efficiency 99
• Spatial resolution 110 µm
• dE/dx resolution 6 consistent with detector
  design report.

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TOF Software

• Simulation
• Two-layered structure for Barrel
• Digitization takes into account light
  production, light propagation and PMT response
  etc.
• Intrinsic time resolution 85 ps
• Calibration reconstruction
• Calibration algorithm contains time correction,
  effective velocity and attenuation calibration.
• Reconstruction results have been used in particle
  identification

26
EM Calorimeter Software

• Simulation
• End-cap is described by G4IrregBox.
• Full simulation of readout electronics is
  included in digitization.
• Energy calibration
• Digit calibration converting ADC channels into
  energy.
• Cluster calibration correcting non-linearity of
  readout signals.
• Reconstruction
• ?E/E 2 _at_ 1GeV
• sz 0.6 cm _at_ 1GeV

27
Muon Chamber Software

• Simulation
• RPC as sensitive detector
• Detailed to each read-out strip
• Reconstruction
• Tracking algorithm is seeded by the tracks
  extrapolated from MDC.
• Searching for hits gap by gap within predefined
  windows.
• Reconstruction efficiency 99 _at_ 1GeV

28
Calibration

• Status
• Developed MDC, TOF and EMC calibration prototype
  algorithms
• Defined calibration data for each sub-detector
• Reconstruction algorithms are able to retrieved
  calibration constants through the framework.

29
Event Display Tool BesVis

• Based on ROOT, OpenGL, X3D and XML
• Support both 2D and 3D view
• Operations and controls available through menu
  and toolbar items
• First version was released in December 2005.

30
Analysis Software Preparation

• Analysis Tools
• Particle ID
• Composition Tools
• Event Data Model
• Analysis Framework
• Event/Physics Tags
• Event Tag
• Physics Tags

• Physics Tools
• RooFit
• Invariant mass fit and etc
• Charm Dalitz Analysis
• In planned
• Statistic Analysis
• In planned

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Status of Particle ID

• DedxPID
• Ready now
• TofPID
• Barrel inner TOF PID
• Ready now
• Barrel outer TOF PID
• Ready now
• MuonID
• Ready now

• EmcPID
• Ready now
• Endcap TOF PID
• Ready now
• TOFQ PID
• Ready now

Combined method for each sub-detector still in
study
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Combined Particle ID

• The probability method
• Standard BESII, combined ?2 distribution, simple
  but need correction, ready now
• The maximum likelihood method
• Combined PDF for each sub-detectors, ready now,
  still need optimization on weight factor
• ANN method
• Variables from all 4 subdetectorsp, charge, pT,
  normPH, numGoodHits, m2, Q, z, Q0, E1, E9, E25,
  depth, totHits,
• ready now but not MUC

33
Status of Composition Tools

• Vertex fitting
• Vertex fit
• Kinematic fit
• 2ndVertex fit

• Telesis
• Kinematic Fit
• BKlamsVTX
• Ks/? reconstruction

All composition tools package worked smoothly
34
No 4C fit
After 4C fit
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From Y(3770)
36
L, Ks From Y(3770)
3MeV
1.2MeV
37
f, w From Y(3770)
38
K From Y(3770)
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D0
40
D
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Inclusive photon Energy
50K ? MC data
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Performance Check

• Reconstruction efficiency of hadron
• PID efficiencies
• X2 distribution
• Photon Detection efficiencies
• Efficiencies from Physics channels
• Summary

By X.B. Ji, G. Li, S.S. Sun, J.Y. Zhang and Yang
Ming etc
44
Efficiencies from physics channels
J/???p 50
??pp-J/?, J/??µµ- 50
??p0p0J/?, J/??µµ- 12
D0?Kp 60
D0?Kppp 28
D0?Kpp0 25
D?K0p 16
D?Kpp 48
Ds ?KKp 40
Ds??p 8
The physics efficiencies have been in a
reasonable range
45
Highlight of Software Preparation
46
Important Steps Towarding Physics
Selection of physics topics ( yellow book, work
with theorists)
Final state particles (g, hadrons, leptons)
Rough estimate of cross-section/branch ratiogt
expected statistics
Prepare event generator for the interested
channels, backgound channels
Go though EventGen?Simulation? Reconstruction?Anal
ysis chain to finalize feasibility study (
Determine cuts, efficiency study, background
suppression etc.)
Calibration/alignment
Data Production, data quality check
Data sampling for interested channels
MC with calibration/alignment database
Extracting physics observables, MC/Data
comparison
Error study
47
Expectation to Analyzers
Each Analyzer should contribute to service in
some form sometime
48
Structrue of BESIII Analysis
Light Hadron
IHEP Physics Group 1
Institution 1
IHEP Physics Group 2
Institution 2
IHEP Physics Group 3
Institution 3
IHEP Physics Group 4
Institution 4
Calibration
IHEP Physics Group 5
Production
Institution 5
Quarlity Check


Analysis Tools
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How If One Wants to Contribute?
Expectations to theorists
Help on selection of physics topics
Help on development of event generators
Help on elucidation of experimental results
Help on paper drafting if you are BESIII members?
Expectations to analyzers
Help on services, as hardware, software,
calibration, data production, quality check, MC,
etc.
Physics analysis
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Summary
The analysis structure has been discussed and
we are going to organize our efforts accordingly
Contributions from theorists play very an
important role in our analysis, support and
suggestions from them are very much welcome
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The Probability method
p
K
BESII standard PID, simple but lots of work on
corrections For Emc deposit energy and Q of TOF,
need a inverse Gassian to get xi Apply histogram
method to extract the p.d.f
The first working PID package, by Dr. Wang
Liangliang
53
The Likelihood method
Measurement
momentum
Particle hypothesis
sub detector p.d.f
Likelihood ratio
Weighted Likelihood ratio
Weighted factor
Additional work on weighted factor
Dr. Huang Bin is working on
54
Neuron Network PID

• Training variables
• Tracking p, charge pT
• dE/dx normPH, numGoodHits
• Tof m2, Q, z
• TofQ Q0
• Emc E1, E9, E25
• Muc discuss with PKU people
• Output
• Return a Value between 1-5, e,µ,p,K, p

Ready after BOSS 6.0.0 release, by Dr. Qin
Gang will be in next BOSS release including all
sub-detector information
55
NN Pid Scheme
dEdx Tof1 Tof2 TofQ Emc Muc
Barrel 1
Barrel 2
Barrel 3
Barrel 4
Barrel 5
Barrel 6
Endcap 1
Endcap 2
Endcap 3
Endcap 4
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Physics Topics Under Study