Transcript Pentaquark Search at Hermes

Extracting Physics From
BESIII Experiment
Yajun Mao
（School of Physics, PKU）
for BESIII Collaboration
Oct 31，2006
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
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Outline
Introduction
Some Physics Reach @ BESIII
BESIII Physics Book
Preparation of Physics Analysis
Summary
Oct.28-Nov.1,2006
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Why BEPCII/BESIII?
High precision experiment：higher
lumi/statistics + better detector
=> higher precision for rare process
Test SM and search for new Physics
CKM elements
Lepton University
J/Y decay
D meson decay
Basic QCD Parameters
Light hadron spectroscopy
Charmonium Physics
Oct.28-Nov.1,2006
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Events Expected at BESIII
Physics
Channel
Energy
(GeV)
Luminosity
(1033 cm–2s –1)
Events/year
J/y
3.097
0.6
1.0×1010
t
3.67
1.0
1.2×107
y’
3.686
1.0
3.0 ×109
D*
3.77
1.0
2.5×107
Ds
4.03
0.6
1.0×106
Ds
4.14
0.6
2.0×106
*D production cross section is taken as 5 nb
Oct.28-Nov.1,2006
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Hints for New Spectroscopy-Challenge QCD
Particle Zoo from
R. Faccini
X(3872)
X(3940)
B decays
J/yccbar
Z(3930)
Y(3940)
gg
B decay
Belle
2003
BaBar
2004
Partial Wave Analysis will be the KEY
DsJ(2317)
DsJ(2458)
tool in the study of spectroscopy,
some of2005
Key
issues should be solved in the future.
Y(4260)
ISR
Continuum
Glueball, hybrid or exotic search in J/y (10109) @ BESIII
J/y  gf0pp
(600)
BESII
X(1860)
J/y g p+p- ’
f0(980) Are they the same particle?
X(1835)
f0(1370)
2
M=1859 +3 +5 MeV/c
X(1835) mass is consistent with the
-10
-25
J/y  (g, , , )
+ f0(1500)
and
also
Tensor
candidates
N obs  264  54
mass of the
S-wave
resonance
X(1860) indicated
2
G < 30 MeV/c (90% CL)
by the pp mass threshold enhancement.
M  1833.7  6.1  2.7 MeV/c 2
(1710)
enhancements2
B( J yf0
gX ) B( X  p p )  (2.2  0.4  0.and
4)  10 G threshold
67
.
7

20
.
3
 7.7 MeV/c
c. f . : B( J y  gX ) B( X  pp )  (7.0  0.4+-10..98 )  10-5
+
-
-4
Many
f0(1790)
A detail angular analysis
will definitely tell us the JPC of X(1835) at BESIII:
35 104 events in J/y  g pp ( = 50%)
J/y  ppbar +X  probe
exotic
B.billion
Zou J/y
4 eventsand
24 10excited
in J/y
g p+baryon
p- ’ (states
= 12%)by10
Oct.28-Nov.1,2006
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Scan of the resonance @ 3.7 - 4.6 GeV to probe spectroscopy
(*)
 (e e  D D ), (e + e -  DS+ DS-(*) ),
+ -
 (e + e -  J /yp +p - ), (e + e -   cJ  ( ))
Test QCD @ 3.7 - 4.6 GeV
Search for exotic ccbar, Y(4260)
 (e + e -  pp ), (e + e -   J /y )
 (e + e -  KK ), (e + e -    )
Probe gluon enhanced hidden ccbar states
D*D Enhancement
at D*D* threshold
Plateau in D*D*
Very little DD
A detail plan to take data @ BESIII should be
made based on the study of R&D in Physics book.
CLEO-c Preliminary
Oct.28-Nov.1,2006
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Dalitz Analysis at BESIII
•K-π+π0, Ksπ+π- vs CP tags, measure strong phase of Kρ, K*π
•K-π+π0, Ksπ+π- vs flavor tags, measure Br of DCSD
•Ksπ+π-, π-π+π0 vs CP tags, search for CP Violation (via same sign CP Tags)
• Strong phase measurement : Measurements of g/3 in BD(*)K(*)
•CP asymmetries across Dalitz Plots
–Ksπ+π-, π-π+π0 vs flavor tags
–D+  K-K+ π+
Light spectroscopy in D Dalitz analysis:
(Kp) s-wave, (pp) s-wave, many isoscalars
M. Pennington’s talk at Charm2006
Oct.28-Nov.1,2006
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Charmonium below open charm @ BESIII
What can we do with 3 billion y(2S)?
Y(2S)  p+p-J/y (31%)
really “pure” J/y sample
a complementary of
J/y peak data!
2002
1977
1974
c in y(2S) g KSKp
y(2S)  g p+p-C
with untagged gamma
M. Voloshin hep-ph/0206240
B(C(2S)  p+p-C ) = 5-10%
2004
Detail study of hC at BESIII
1980
C(1S) sample from J/y  g C(1S)
used to study the light spectrum
Oct.28-Nov.1,2006
c,0,1,2 sample
useful to understand
the decay dynamics of
ccbar
and light hadron with
same
JPC!
1975
Q. Zhao, hep-ph/0508086
1974
2S – 1D mixing : “p” 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, D+DM. Voloshin hep-ph/0402171
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Scan Run will be crucial at BES-III: ECM = 3970-4260 GeV
)
From the current experimental indication!
Charmonium Decays of y(4040), y(4160), and Y(4260)
*
CLEO-c Preliminary
Ron Poling talk at Charm2006
CLEO-c PRL 96, 162003 (2006)
Oct.28-Nov.1,2006
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BES III Charm Mixing (1)
Quantum Correlations in D0D0 decays from the y(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 K+pmixing: D0 K-p+
D0 D0 K-p+
D0D0 (Kev Kev)
 
G( D D  (l l )) x + y

G( D 0 D 0  (l l  ))
2
0
0
2
2
G( D 0 D 0  ( K -p + )(K -p + )) x 2 + y 2 p B 2 K -p +

2
0
0
- +
+ 2
G( D D  ( K p )(K p ))
2
q B K +p • BESIII PID system
2
•Two missing neutrinos in events
•Electron PID can suppress background
–dE/dx, resolution (6-7)%
•The selection efficiency is similar as the
Kπ channel
–Two layer barrel TOF, time resolution
~100ps, ~83% solid angle coverage
•Background level is also negligible while
running a small MC data sample (~1% of
20fb-1). More detail study is needed.
–1 layer endcap TOF, ~110ps
• Selection efficiency is >20% with a K/π
double mis-identification rate at < 10-4
level
With 20fb-1(4-5 years running) at Ψ(3770) peak
RM <10-4
Oct.28-Nov.1,2006
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BES III Charm Mixing (2)
Be careful e+e-  DD( ng)(mp)
no resonant contribution, TQCA will be lost!
D0 Momenta from CLEO-c Preliminary
D*D*
BESIII
Data 4160 MeV
DD*
DD
Evidence for “multibody” (MB) events, e.g. e+e-DD*p:
Oct.28-Nov.1,2006
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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 C=+1 of gD0D0bar and gD0D0barπ0
from D*Dbar and D*D*bar decays
CLEO-c (3x106D0D0b)
parameter
BESIII(20fb-1)
value
C=-1
C=+1
C=-1
C=+1
y
0
±0.015
±0.007
±0.003
±0.002
x2
0
±0.0006
±0.0003
±0.00013
±0.0001
cosδKπ
1
±0.15
±0.13
±0.035
±0.04
xsinδKπ
0
─
±0.010
─
±0.003
Oct.28-Nov.1,2006
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CP eigenstate Tags
•CP +
•CP –
–K+K- (3.89X10-3 )
–KSπ0(0.012)
–π+π- (1.38X10-3 )
–Ksη (3.9X10-3)
–Ks π0π0
–KS η’ (0.0094)
–π0π0 (8.4X10-4)
–KSρ0 (0.0078)
–KSKS (7.1X10-4)
–Ksω (0.012)
–ρ0 π0 (3.2x10-3)
–KSφ (4.7X10-3)
In 20fb-1 Ψ(3770) data, we can get
> 4.5x105 CP+ tags and > 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
Oct.28-Nov.1,2006
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CP Violation at ψ(3770) at BESIII
K+
Find:
K
-
D
0
D
ACP 
Af
2
Af
2
- Af
2
+ Af
2

2 Im( A1* A2 ) sin( 1 -  2 )
A1 + A2
2
2
+ 2 Re( A1* A2 ) cos(1 -  2 )
•CP violating asymmetries can be
measured by searching for events with two
CP odd or two CP even final states:
0
π
π
-
K K vs pp
+
p+p-, K+K-, p0 p0, Ksp0 ,
for the decay of ψ  f1 f 2
CP( f1 f 2 )  CP( f1 )  CP( f 2 )  (-1) L  CP(ψ)  +
ACP sensitivity 10-2 - 10-3
Beam
constraint
Mass
Oct.28-Nov.1,2006
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Leptonic and Semileptonic decays at BESIII
2

m
G
G ( D+  l + ) 
f D2+ ml2 M D+  1 - 2l
 M +
8p

D
2
F
G( D  Pl ) 
BESIII:
Integrate Lumi.
20fb-1 DDbar
MC simulation
Vcd/Vcd 1.7%
D
Oct.28-Nov.1,2006
l

p
2
2
F
G Vcq p 3
24p
3
2

2
V
 cd

( )
f+ q
2
2
Vcs/Vcs 1.6%
D
高能物理学会第7届年会，桂林
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
K
15
BESIII Physics Yellow Book
Part One: The BES-III Experiment and its Physics
Conveners: Jian-Ping Ma and Ya-Jun Mao
Part Two: e+e- 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
Oct.28-Nov.1,2006
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Chapters of the Yellow Book
Part One: The BESIII experiment and its physics
Chapter 1. Physics goal of BESIII
Chapter 2. The BESIII detector
Chapter 3. Offline Software
Chapter 4 Analysis tools
Jian-Ping Ma and Ya-Jun Mao
Jian-Ping Ma
Ya-Jun Mao
Ya-Jun Mao and Wei-Dong Li
Kang-Lin He
Part Two: e+e- 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
Oct.28-Nov.1,2006
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Chapters of the Yellow Book
Chapter 16. Two-photon physics
Chapter 17. Soft pions and a0-f0 mixing
Part Four: Charmonium Physics
Bing-Song Zou and Hai-Bo Li
Han-Qing Zheng
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
Oct.28-Nov.1,2006
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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
Oct.28-Nov.1,2006
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Status of The Book
• Proposed in Jun, 2005
• 1st meeting: Mar 6, 2006, in Xiamen:The 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
Oct.28-Nov.1,2006
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Analysis Preparation
Software +
Physics
Event
Simulation
Hardware
Detector
Response
Detector R&D
Mass Production
Data
Acquisition
Recon.
+ PID
Physics
Analysis
Real
Collision
Oct.28-Nov.1,2006
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GEANT4
GAUDI
BOOST
BOSS
Oct.28-Nov.1,2006
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Event Display
Physics Analysis
Physics Analysis
Reconstruction
Detector
Simulation
Event
Generator
Overview of BESIII Offline Software
ROOT
22
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 …
Oct.28-Nov.1,2006
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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
•
Oct.28-Nov.1,2006
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
Oct.28-Nov.1,2006
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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 nonlinearity of readout signals.
 E /E=[(p0/E)  (p1/ 4 E)  p2]%
• Reconstruction
– ΔE/E = ~2% @ 1GeV
– σz = 0.6 cm @ 1GeV
Oct.28-Nov.1,2006
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Muon Chamber Software
• Simulation
– RPC as sensitive
detector
– Detailed to each readout strip
• Reconstruction
Window
Ext track
Oct.28-Nov.1,2006
Fired
strips
– Tracking algorithm is
seeded by the tracks
extrapolated from MDC.
– Searching for hits gap
by gap within
predefined windows.
• Reconstruction
efficiency: ~ 99% @
1GeV
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Calibration
calibUtil interface
Write/register
Search
Read
Metadata (persistent)
MySQL rdbms

Signifies
“uses” or
“accesses”
Data (persistent)
Dead chns CAL calibs
(XML)
(ROOT)
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.
Oct.28-Nov.1,2006
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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.
Oct.28-Nov.1,2006
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Analysis Software Preparation
• Analysis Tools
• Physics Tools
– Particle ID
– Composition Tools
• Event Data Model
• Analysis Framework
• Event/Physics Tags
– Event Tag
– Physics Tags
Oct.28-Nov.1,2006
– RooFit
• Invariant mass fit and
etc
– Charm Dalitz Analysis
• In planned
– Statistic Analysis
• In planned
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Status of Particle ID
• DedxPID
• EmcPID
– Ready now
– Ready now
• TofPID
• Endcap TOF PID
– Barrel inner TOF PID
• Ready now
– Barrel outer TOF PID
• Ready now
– Ready now
• TOFQ PID
– Ready now
• MuonID
– Ready now
Combined method for each sub-detector still in study
Oct.28-Nov.1,2006
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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 subdetectors：p, charge, pT, normPH,
numGoodHits, m2, Q, z, Q0, E1, E9, E25, depth, totHits,
ready now but not MUC
Oct.28-Nov.1,2006
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Status of Composition Tools
• Vertex fitting
• Telesis
– Kinematic Fit
• BKlamsVTX
– Ks/Λ reconstruction
– Vertex fit
– Kinematic fit
– 2ndVertex fit
All composition tools package worked smoothly
Oct.28-Nov.1,2006
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J/ψ  ρπ
J/ψ  ρπ
No 4C fit
M gg
J/ψ  ρπ
After 4C fit
Oct.28-Nov.1,2006
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π  γγ From Y(3770)
0
π 0  γγ
M gg
Oct.28-Nov.1,2006
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, Ks From Y(3770)
KS  π + π ~3MeV
  pπ
~1.2MeV
Oct.28-Nov.1,2006
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,  From Y(3770)
φ  K+K-
ω  π+ π- π0
Oct.28-Nov.1,2006
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K* From Y(3770)
K *0  Kπ
K *  K S π 
Oct.28-Nov.1,2006
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D0
-
D K π
0
D0  K - π + π + π -
+
π+
D0  K - π + π 0
Oct.28-Nov.1,2006
D0  K S π + π -
高能物理学会第7届年会，桂林
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D+
D+  K - π + π +
+
+
+
D  KSπ π π
Oct.28-Nov.1,2006
-
D+  KSπ +
D+  KSπ + π0
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+ 
ψ  π π J/ψ
M rec
Oct.28-Nov.1,2006
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χ  γJ/ψ
J
c
χ
2
c
χ
1
c
χ
0
c
Inclusive photon Energy
Eg
J/ψ  μ +μ -
50K Ψ’ MC data
Oct.28-Nov.1,2006
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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
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
43
Efficiencies from physics channels
J/Ψ→ρπ
~50%
Ψ’π+π-J/Ψ, J/Ψμ+μ-
~50%
Ψ’π0π0J/Ψ, J/Ψμ+μ-
~12%
D0Kπ
~60%
D0Kπππ
~28%
D0Kππ0
~25%
D+K0π
~16%
D+Kππ
~48%
Ds KKπ
~40%
Dsη’π
~8%
The physics efficiencies have been in a reasonable range
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
44
Highlight of Software Preparation
Simulation, Reconstruction/Calibration and Analysis
software are in a good shape and reasonable status
We are ready to start physics study with current
version of BESIII software
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
45
Important Steps Towarding Physics
Simulation before data is ready
Selection of physics topics ( yellow book, work with theorists）
Final state particles (g, hadrons, leptons)
Rough estimate of cross-section/branch ratio=> expected statistics
Prepare event generator for the interested channels, backgound channels
Go though EventGenSimulation ReconstructionAnalysis chain
to finalize feasibility study ( Determine cuts, efficiency study, background
suppression etc.)
Extracting Physics from data
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
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
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Expectation to Analyzers
Light Hadron
Charmonium
Charm
R
Tau
Calibration
Production
Quarlity Check
Analysis Tools
MC/Data
Each Analyzer should contribute to service in some form sometime
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
47
Structrue of BESIII Analysis
Light Hadron
Institution 1
IHEP Physics
Group 1
Charmonium
Institution 2
Charm
IHEP Physics
Group 2
R
Institution 3
Tau
IHEP Physics
Group 3
……
Institution 4
Calibration
Institution 5
Production
IHEP Physics
Group 4
IHEP Physics
Group 5
Quarlity Check
……
Oct.28-Nov.1,2006
Analysis Tools
高能物理学会第7届年会，桂林
……
48
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
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
49
Summary
BESIII offline software are in good shape and
reasonable status, intensive test and check are
badly needed to optimize and improve the software
The physics yellow book is undergoing, we need to
hurry up to provide proofread as scheduled
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
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
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THANK YOU！
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
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The Probability method
i 
x measure - x exp ected
(i  tof, dE / dx )
 measure
 i  gauss -1 (pdf )(i  Emc, T ofQ)
 2    i2
i
P  Pr ob(  2 , n )
K
π
PK
PK + Pp
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
Oct.28-Nov.1,2006
The first working PID
package, by Dr. Wang Liangliang
高能物理学会第7届年会，桂林
52
The Likelihood method
momentum
Measurement
Particle hypothesis
L(p, x, h )   i pdfi (p, x i , h )
L(p, x, h )
F(p, x, h ) 
 j L(p, x, j)
L(p, x, h )  w (p, h )
F(p, x, h ) 
 j (L(p, x, j)  w (p, j))
Additional work on weighted factor
Oct.28-Nov.1,2006
Dr. Huang Bin
is working on
高能物理学会第7届年会，桂林
sub detector p.d.f
Likelihood ratio
Weighted
Likelihood ratio
Weighted factor
53
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,π,K, p
Ready after BOSS 6.0.0 release, by Dr. Qin Gang
will be in next BOSS release including all sub-detector information
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
54
NN Pid Scheme
dEdx
Tof1
Tof2
TofQ
Emc
Muc
1
2
3
Barrel
4
5
6
1
2
Endcap
3
4
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
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Physics Topics Under Study
Oct.28-Nov.1,2006
高能物理学会第7届年会，桂林
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