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2006-6-11 Gang RONG, IHEP, BES collaboration
1
Prospects of Charm Physics at BES-III-- Based on Monte Carlo Study of D decays
Gang RONGInstitute of High Energy Physics, Beijing, China
e- e+
Ψ(3770)
D
D
Precision measurementsIntroduction
D0D0-bar MixingProbes for New Physics
Search for CP violationSearch for some rare decays
Other topics Note: I borrow some slides from some wonderful talks on studies of Charm transitions. For a working group I make the presentation. I would like to thank Prof. D.S. Du for some useful discussion about charm decays.
SummaryPRC--US Workshop on e+e- Collision Physics, Beijing, June , 2006
2006-6-11 Gang RONG, IHEP, BES collaboration
2
The people who involved in the Monte Carlo study of the Charm decay properties, (reported in this talk) with BES-III/BEPC-II. During the last three weeks, the 4 graduate students worked on full Monte Carlo simulation to study the charm decays to be observed with the BES-III/BEPC-II.
2006-6-11 Gang RONG, IHEP, BES collaboration
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IntroductionCharm plays an important role in understanding the SM (standard model) dynamics in two respects:
Precision measurements of decay constants fD, fDs, form-factors of semileptonic decays of Charm mesons provide the calibration of Lattice QCD calculation. In turn, the very precise calculation of the ratio of the decay constants fD/fB, fDs/fBs and form-factors from LQCD support measurements for B physics.
Precision measurements
The parameters of Standard Model are:mixings and mass fermion,,sin, 2
, HwF MG θα
udV usV ubV
cdV csV cbV
tdV tsV tbV
='d
's'b
dsb
Mass eigenstates
2
211 λ− λ )(3 ηρλ iA −
2
211 λ−λ− 2λA
)1(3 ηρλ iA −− 2λA− 1
)( 4λΘ+
The 4 quark mixing parameters ( ) reside in CKM matrixηρλ ,,, A
CKMWeak eigenstates
CKM
To understand the quark mixing and CP violation in SM, and detect New Physics in flavor change sector, one must determine the CKM elements as precisely as possible !
2006-6-11 Gang RONG, IHEP, BES collaboration
4
Now With Charm data one can calibrate the QCD calculations. If the QCD pass the test with the charm data, the theory errors of a few % on B system decay constants & semileptonic form factor are achieved, and the CKM elements achieved to
+
η
ρ
Then the uncertainties will be reduced to
The constraints in ( ) plane arising from some measurements …
ηρ , The width of band is mainly dominated by theoretical (LQCD) errors on fB, fBs and B semileptonic form factors .
500 fb-1 @ BABAR/Belle
2006-6-11 Gang RONG, IHEP, BES collaboration
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Measurements of some transition rates of Charm provide probes for New Physics.
Probes for New Physics
In the SM, the D0D0 mixing, CP violation and rare decays of charm are all small. However, some New Physics effects beyond the SM can enhance the mixing, the CP violation and the rare decays. So search for the mixing, the CP violation and the rare decays provide the unique opportunities to search for New Physics beyond the SM indirectly.
200 10mixing −≤DD310asymmetry −≤CP610decays Rare −≤
2006-6-11 Gang RONG, IHEP, BES collaboration
6
For the precision measurements, one need a large data sample, high quality data and to do absolute measurements.
Threshold data
Using the data collected near threshold, one can precisely measure the absolute branching fractions, decay constants, form factors and/or |Vcd| and |Vcs|, …
e- e+
Ψ(3770)
D
D
),( 00 −+−+ → DDDD DDee
Near the DD-bar threshold, Only DD-bar production. Event is very clean.Beam energy constraint mass
22DbeamEC pEM −=
Or kinematic fitted massto reconstruct the D decay
fitM
2006-6-11 Gang RONG, IHEP, BES collaboration
7
Charm Physics at BES-III
BES-III will be the successor of the previous successful
BES-I and BES-II
Luminosity reach to 1033 at Ecm = 3.78 GeV (compare to 1031 for BEPC).
BEPC
Large angle coverage, good charged PID & momentum resolution, good photon energy resolution.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Two rings, 93 bunches:• Luminosity
1033 cm−2 s−1 @ 3.78 GeV 6× 1032 cm−2 s−1 @ 3.10 GeV 6× 1032 cm−2 s−1 @ 4.20 GeV
BESIII Detector
MDC: small cell & He gasσxy=130 µmsp/p = 0.5% @1GeVdE/dx=6%
TOF:σT = 100 ps Barrel
110 ps Endcap
Muon ID: 9 layer RPC
Data Acquisition:Event rate = 3 kHzThruput ~ 50 MB/s
Magnet: 1 T Super conducting
EMCAL: CsI crystal∆E/E = 2.5% @1 GeVσz = 0.6 cm/√E
Trigger: Tracks & ShowersPipelined; Latency = 6.4 µs
The detector is hermetic for neutral and charged particle with excellent resolution ,PID, and large coverage.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)Absolute BFs BES III Full MCBES III Full MC simulation
Charm absolute branching fractions are very important. Most branching fractions of charm decays are normalized to them. The branching fractions are also used to normalize the B & Z decay branching fractions (Rb & Rc) … They also entry the CKM element measurements.
)()()( 0
obs00
0+−
+−+−
→×→
=→πε
ππKDN
KDNKDBtagD
)%24 ,58( 00 −+−+ → D DD% D DDee
DD decay to all possible final states according to PDG04
)()()(
tag
obs
++−+
++−+++−+
→×→
=→− ππε
ππππKDN
KDNKDBD
e+ e-
D0 K+
tag
D0
D0 π+
+π
π+
π-
−K
Singly tagged D0With double tag method we can measure the absolute BFs
Real simulation of data
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
)3770(ψ→−+ ee
58.0 42.000 DD −+ DD
+−πK
−++− πππK−+ππ0K
0ππ +−K
llK ν+−
ll νπ +−
llK νπ +−0
00 πππ −+K
Charge conjugation
Charge conjugation
…
++− ππK
+π0K0πππ ++−K
llK ν+0
llK ν+0*llK νπ ++−
−++ πππ0K
00 ππ +K
µνµ +
…
Physics Release Boss 6.0.2
We would like to thank Prof. W.D. Li, Prof. H.M. Liu, Miss S.P. Wen, Mrs. Z.Y. Deng, G.W. Yu for kind help with BES-III software, we thank Dr. G.X. Sun, Mrs. J. Su, Mrs. Y. Yang and Mrs G.H. Du for help with computers.
Generated Monte Carlo eventsGenerated 800 pb-1 @ 3.773 GeV
BES-III software
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)Current statusAbsolute BFs
B(D+→Κ-π+π+)B(Do →K-π+)
PDG042.43.80 ±0.09
CLEO-c3.13.91±0.08 ±0.09
ALEPH3.83.90±0.09±0.12CLEO3.63.82±0.07±0.12ExperimentError(%)B (%)
B(Do →K-π+) 56pb-1
PDG047.79.1±0.7CLEO-c3.99.52 ±0.25±0.27
MKIII14.99.1±1.3±0.4CLEO10.89.3±0.6±0.8SourceError(%)B (%)
B(D+→Κ-π+π+) 56pb-1
2.2% projected error with 281 pb-1
1.8% projected error with 281 pb-1
CLEO-c
Three best measurements:
BES-II and CLEO-c(not in PDG average)
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
)%04.083.3()( 0 ±=→ +−πKDB
7504330000tag
±=D
N12512350)( 0 ±=→ +−πKDN
%4.74=ε
INPUT) (MC 80.3)( 0 %KDB =→ +−π
−+πK 0ππ −+K
+−−+ πππK +−ππ0K
H.L. Ma did the nice analysis.
bcMbcM
bcM bcM
bcM
+−πK
B(Do →K-π+)Absolute BFs Double tag analysis, Independent of Double tag analysis, Independent of
Luminosity and cross section in the Luminosity and cross section in the double tag measurementsdouble tag measurements
BES III MCBES III MC 1fb 02/%3.0/ −=BBδ
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)Absolute BFs
H.L. Ma did the nice analysis.
)%12.048.9()( ±=→ ++−+ ππKDB
440158800tag
±=−DN1008130)( ±=→ ++−+ ππKDN
%0.54=εbcM bcM
bcM
B(D+→Κ-π+π+)
3.1/ %BB =δ
++− ππK
−−+ ππK
0πππ −−+K
−−+ πKK
−π0
K +−− πππ0
K
00ππ −K
Independent of Luminosity and cross Independent of Luminosity and cross section in the double tag measurementssection in the double tag measurements
BES III MCBES III MC 120/%3.0/ −= fbBBδ
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)Absolute BF(D+
S φπ+) Current status
)( %5.12/ BABARBB =δ
)c (CLEO %0.4/ −=BBδ
CLEO-c hope to achieve the accuracy level up to 4% with 750 pb-1 @4.17 GeV.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
εϕπ
ϕπ×
→=→
−
++++
tag
obs)()(SD
SS N
DNDB
~2.3 fb-1
Absolute BF(D+S φπ+)
He made the full Monte Carlo simulation.
−−−− πϕπ 0
00* ,,, fKKKK
tag mode
bcM
%23=ε20380)( ±=→ ++ ϕπSDN
21546161tag
±=−SD
N
)%18.059.3()( ±=→ ++ ϕπSDBr
+ϕπM
%5/ =BBδ)fb (20 %7.1/ 1−=BBδ
BES III Full MCBES III Full MC simulation
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
22233
2
2 |)(|||24
)( qfVpGdq
PlDdcqP
F+=
→Γπ
ν
The parameters of Standard Model are:mixings and mass fermion,,sin, 2
, HwF MG θα
The 4 quark mixing parameters ( ) reside in CKM matrix
udV usV ubV
cdV csV ubV
tdV tsV tbV
='d's'b
dsbMass eigenstates
ηρλ ,,, A
νPlD →D Semi-leptonic Decays
Form Factor
CKMWeak eigenstates
Absolute branching fractions give direct measurements of the CKM matrix elements Vcd& Vcs and form factors
Questions: Does the CKM fully explain quark mixing? CP Violation?
To detect New Physics in flavor change sector, one must know the CKM well
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
Current status
2006-6-11 Gang RONG, IHEP, BES collaboration
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missmissmiss PEU −=Neutrino carries energy and momentum away
Should be around zero
Fully reconstruct one D
e+ e-
D0 K-
tag
D0
D0 π+
−eν
π+
Require two additional charged track and no additional photons
π-
)( ++ πK
−+→ πKD0
+−−+→ πππKD0
BCM
BCM
BES III Full MCBES III Full MC simulation
22233
2
2 |)(|||24
)( qfVpGdq
PlDdcqP
F+=
→Γπ
ν
00ππ −+→ KD
−+→ ππ00KD
)pb 800( 1−≈L
She did the nice analysis.
Precision Measurements at BES-III (con’t)D Semi-leptonic Decays
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
%45=ε805528)( 0 ±=→ +− νeKDN
600359884 ±=tagN
)%05.041.3()( 0 ±=→ +− νeKDBr
DDe e →× −+6109.4)pb 800( 1−≈L
%48=ε29707)( 0 ±=→ +− νπ eDN
)%02.041.0()( 0 ±=→ +− νπ eDBr
%5.1/ =BBδ
%1.4/ =BBδ
νπ +−→ eD 0
missmissmiss PEU −=
missmissmiss PEU −=
ν+−→ eKD0
ν+−→ eKD0
missmissmiss PEU −=
She made the nice full Monte Carlo simulation.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
1.0%τ∆τ
0.6%τ∆τ
s
s
D
D
D
D ≈≈
Well measured
11122 10|)0(||53.1)( −+ ×=→Γ sfVKeD K
cseν11122 10|)0(||01.3)( −
+ ×=→Γ sfVeD cdeπνπ
2pole
22
/1)0()(
mqfqf
−= +
+
To extract Vcs & Vcd need form factor from theory at one fixed q2 point.CKM Matrix at BESIII
22233
2
2 |)(|||24
)( qfVpGdq
PlDdcqP
F+=
→Γπ
ν
22
D
D2
cq
cq
2f∆f
2τ∆τ
2B∆B
V
V∆
+
+
=
Form factor from theory (Lattice QCD). Assuming Δf/f ~3% , BESIII will approach
BESIII: L=20 fb−1
ψ(3770) MC simulation
lνD π
lνD
Κ
δVcd/Vcd 11% δVcs/Vcs 4%
BESIII
δVcd/Vcd ~1.7% δVcs/Vcs ~1.6%l
νD π
lνD Κ
Quark models, HQET, Lattice & other methods have all been invoked to calculate form factor absolute normalizations. These calculations have been done
mostly at q2 =0 or q2 =q2max. (i..e w=1, just like F in Vcb in B →D* lν)
Great contribution to CKM Unitarity
2006-6-11 Gang RONG, IHEP, BES collaboration
21
Precision Measurements at BES-III (con’t)
ν++ → eKD )892(0*
eeKD ν++ → 0*
eeKD ν+−→ *0
BES-II
BES-III MC simulation
Umiss(GeV)
Eve
nts
( )
( )
( )
( ) { }δθ θ
θ θ
θ θ
χ θ θ
+
−
−
+
+ − = +
+
+
∫
2 22 2
2 22 2
22 222 20
2 2 20
2
(1 cos )sin ( )
(1 cos )sin ( )1A 2sin cos ( )
8 sin cos ( ) ( ) e8
R
( )
l V
l V
l V
V
o
l
iH q h q
H q BW
H q BW
d q H q B
O
W
A
Ae BW
H0(q2), H+(q2), H-(q2) are helicity-basis form factors which are computable by LQCD A new factor h0 (q2)is needed to describe s-wave interference piece.
S-wave interfere asymmetry
cosV
Focus FPCP 2006
2006-6-11 Gang RONG, IHEP, BES collaboration
22
Precision Measurements at BES-III (con’t)XeDDD S
+++ →,, rates Inclusive 0
2006-6-11 Gang RONG, IHEP, BES collaboration
23
Dif06 I.Shipsey
Measurements of fD and fDs are very important for improving our knowledge on CKM matrix, and to calibrate the LQCD.
Precision Measurements at BES-III (con’t)Status of measurements of fD
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)
Dif06 I.Shipsey
Previous measurements of fD
MARK-III set an upper limit
BES first observed 1 & 3 signal events and measured fD
2006-6-11 Gang RONG, IHEP, BES collaboration
25
Precision Measurements at BES-III (con’t)Previous measurements of fD
c)(CLEO %8 −=∆
D
D
ff
CLEO-c observed 50 signal events and made a nice measurement
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision Measurements at BES-III (con’t)fD at BESIII J. Liu made the
nice full Monte Carlo simulation.−−−+− → πππ 0, KKD
bcM
missmissmiss PEU −=
++ → π0KD
%53=ε0.56.20)( ±=→ ++ νµDN
33559720tag
±=−DN
DDe e →× −+6109.1)pb 306( 1−≈L
)%016.0065.0()( ±=→ ++ νµDBr
),( 0 −−−+ πππ KK
+−−−−−+−−+ πππππππππ 000 ,,, SS KKKK−−+− πππ KKK S ,00
modes tag 6For
%9/ ,18/ == DD ff %BB δδ
%2.1/ ≈DD ffδ
)3770(@ fb 20 1 ψ−
analyzed
2006-6-11 Gang RONG, IHEP, BES collaboration
27
Precision Measurements at BES-III (con’t)
e+ e-
D+S
D-S
+µ
K-
K+
ν
π-
%52=ε80.63)( ±=→ ++ νµSDN
)fb 10( 51626894 1
tag S
−≈±=− LN D
−+−+ →× SS DDe e6109.1
)%057.0453.0()( ±=→ ++ νµSDBr
−−−+−−− ππππϕπ 0000* ,,,, fKKKKK SS
modes tag 5For
%2.6/%,5.12/ == ++SS DD ffBB δδ
%1.3/%2.6/ == ++SS DD f, δ BBδ
fDs at BESIII D-s tag
bcM
−ϕπSingle tag mode
missmissmiss PEU −=
)fb 02(L %2/ 1−=≈++SS DD fδf
2006-6-11 Gang RONG, IHEP, BES collaboration
28
Precision Measurements at BES-III (con’t)
fD(s) at BESIII2
cd(s)
cd(s)22
D
D
D
D
|V||V|
BB
21
21
(s)
(s)
(s)
(s)
∆+
∆
+
∆=
∆
τ
τ
ff
0.06%|V||V|∆1.1%
|V||V|∆
cs
cs
cd
cd ≈≈
1.0%τ∆τ
0.6%τ∆τ
s
s
D
D
D
D ≈≈
4)%~2( B∆B
≈With 20fb−1
at BESIII
3 generation unitarity global fit:hep-ph/0406184 CKMfitter group
BESIIIff %2.1∆
D
D ≈
BESIIIff
%1.2∆
s
s
D
D ≈ Ecm=4.03 GeV
Ecm=3.773 GeV
Challenge LQCD Prediction
2006-6-11 Gang RONG, IHEP, BES collaboration
29
Precision Measurements at BES-III (con’t)
7.5~1.04.015.0~1002.08.0
16.61.04.1 5.00.52.06.50.41.52.30.31.2
CLEO-cMode+−→ πKD 0
)fb (1 / -1BBδ )fb (20 / -1BBδ )04(PDG / BBδ
++−+ → ππKD
ν+−→ eKD 0
νπ +−→ eD 0
νµ −+ →D
+Df
281 pb-1
Short summaryRelative error (%) on the measurements
Statistical error only
2006-6-11 Gang RONG, IHEP, BES collaboration
30
Precision Measurements at BES-III (con’t)
Relative error (%) on the measurementsShort summary
142.19.4384.319 N/A7.030253.013252.09.0
Mode
ν++ → eKDS0
)fb (1 / -1BBδ )fb (20 / -1BBδ )04(PDG / BBδ
νµ ++ →SD
++ → φπSD
νφ ++ → eD S
ντ ++ →SD
+SDf
Statistical error only Assuming Ecm=4.03 GeV
2006-6-11 Gang RONG, IHEP, BES collaboration
31
−+KK−+ππ…
New physics will enhance New physics will enhance xxDD by entering new by entering new particles in the virtual particles in the virtual state contribution. state contribution.
Search for D0D0-bar Mixing00 :mixing DD ⇒
)('produce' uc− )('decay' cu−
shifts energy of CP eigenstates
Γ∆
= DD
Mx
Change of identity due toThe box diagrams are proportional to two Cabibbo suppressed factors and are suppressed by the GIM mechanism. It involves intermediate down-quarks which are much lighter than top for K0-K0bar and B0-B0bar mixing.
Γ∆Γ
=2Dy Mixing
parameters
shifts lifetimes of CP eigenstates
2
22DD
mixyxR +
≡The standard model predicts very small D0-D0bar mixing, xD& yD 10-2.≤
2006-6-11 Gang RONG, IHEP, BES collaboration
32
e+ e-
D0 K-
tag
D0
D0
π+
D0
K-
π+D0
π+K-
mixing
00)3770( DD→ψ
Coherence simplifies study no DCSD
Search for D0D0-bar Mixing
e+ e-
D0 K-
tag
D0
D0 π+π+
π-
D0
K-π+
D0π+
K-
mixing
DCSDare coherentDCSD+−+−→→ ππψ KKDD
00)3770(Can not measure the time evolution of D0 meson decays, DCS decay can not be separated from the final states. The level of the DCSD background is higher than the level of the mixing.
requiring L to be even, DCSD1L )3770( =ψ
So DCSD can not happen
2006-6-11 Gang RONG, IHEP, BES collaboration
33
Search for D0D0-bar Mixing
J. Liu made the nice full Monte Carlo simulation.
Rmix sensitivity : 1.5x10−4 with 20 fb−1
BESIII
at BESIII (based on this MC simulation)
K−π+ vs K−π+
2 background events are observed
K−π+ vs K+π−
BESIII Monte Carlo Simulation
BCM
BCM
2006-6-11 Gang RONG, IHEP, BES collaboration
34
Search for Direct CP Violation
e- e+
Ψ(3770)
D
D
+K−K
+π−π
0
0
+CP
+CPCP violating asymmetries can be measured by searching for events with two CP odd or two CP even final states, such as,
π+π−, K+K−, π0 π0, ρ0π0 …+CPΚsπ0, Κsρ0, Κsφ , Κsω ...−CP
21ψ(3770) of decay thefor ff→−=−⋅⋅= L
2121 1)()CP()CP()CP( ffff
+=)]3770(CP[ ψ
If we observed two CP odd or two CP even final states simultaneously we need to analyze many channels to elucidate the sources of CP violation !BESIII MC simulation
2006-6-11 Gang RONG, IHEP, BES collaboration
35
Search for Direct CP Violation
CP+(-) eigenstate Tags
+CP π+π−, K+K-, π0 π0, ρ0π0, KS KS KSπ0 π0 …Κsπ0, Κsρ0, Κsφ , Κsη, Κsη′, Κsω ...−CP
from 20 fb-1Ψ(3770) data, we can select about 4x105 CP+ tags and about 4x105 CP- tags. With the large CP tagged samples we can probe the direct CP violation, measure the strong phase difference between the direct and DCS amplitudes, and measure other mixing parameters.
2006-6-11 Gang RONG, IHEP, BES collaboration
36
−+−+ K vs KKK
BCM
Search for Direct CP Violation20 fb-1
ACP < 5x10-3 @ 90% C.L.
−+−+ ππ vs KK
−+−+ πππ π vs
−+−+ K vs KKK
−+−+ ππ vs KK
−+−+ πππ π vs
BCM
BCM
440 events
340 events
66 events
−+−+ K vs KKK
−+−+ ππ vs KK
−+−+ πππ π vs
sensitivity
2006-6-11 Gang RONG, IHEP, BES collaboration
37
Measurement of Strong PhaseI. Shipsey
Dr
Flavor mode
Dδ
Using the CP tag samples (CP+ vs Kπ double tags & CP- vs Kπ ), we can measure the strong phase difference between the direct and DCS amplitudes, which appears in the time dependent mixing measurements.
Dδ
~9000 CP+ vs KπDouble tags~9000 CP- vs Kπ
cos δD < 8% at BESIII
D.H. Zhang modified
2006-6-11 Gang RONG, IHEP, BES collaboration
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Search for rare decaysObservation of D+
FCNC and lepton number violating decays could indicate new physics.
In the SM (Standard Model), the short distance charm FCNC (flavor changing neutral currents) are much highly suppressed by the GIM mechanism than down type quarks due to the large mass difference between up type quarks.
The dilepton decay proceeds by penguim annihilation or box diagram.
( )( )( )
0 -10
0 -6
0 -6
up to 10
up to 10
up to 10
D e e
D
D e
+ −
+ −
±
→
→ µ µ
→ µm
B
B
B
The decay is strictly forbidden in the SM.0D e ±→ µ m
New Physics (Beyond the Standard Model ) may enhance these decay processes. For example, R-parity violating SUSY:gives
(Burdman et al., Phys. Rev. D66, 014009).Best limits are from BABAR
SM 230 10~)( −−+→ eeDB130 103~)( −−+ ×→ µµDB
Search for these kind of rare decays can probe New Physics
2006-6-11 Gang RONG, IHEP, BES collaboration
39
Search for rare decaysCurrent status Experiment sensitivity is up
to about 10-5~10-6Branching Fraction
Talk from Ian Shipsey
2310−
Expt. sensitivity 10-5-10-6
Just beginning to confrontmodels of New Physics inan interesting way.
Still plenty of roomfor New Physics.
Outlook: promisingCDF/D0, B factories,CLEO_c/BES IIIsuperflavour
G. Burdman and I. Shipsey Ann. Rev. Nucl. Part. Sci. 53 431 (2003)arXivhep-ph/0310076 (updated 12/2005).
2006-6-11 Gang RONG, IHEP, BES collaboration
40
−+eeφ
−+eeK0
−+eeK 0*
−+ µe
−+µφe
−+µeK0
−+ µeK 0*
We studied the rare decay processes with untagged D mesons to increase sensitivity with full Monte Carlo simulation based on 500 pb-1 at .ψ(3770)
Experimental sensitivity
to access the decay
Search for rare decays
M.G. Zhao made the full Monte Carlo simulation.
2006-6-11 Gang RONG, IHEP, BES collaboration
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−++ eeπ ++− eeπ
−++ eeK ++− eeK
+−−+ → eeKDS5103~ −×
Search for rare decays
He made the full Monte Carlo simulation.
The sensitivity will be 10-7 for D decays based on 20 fb-1 of ψ(3770) data at BESIII
2006-6-11 Gang RONG, IHEP, BES collaboration
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Note: the * means that the upper limit is estimated (it is not obtained from full Monte Carlo simulation)
Search for rare decays
with 20 fb-1 data at ψ(3770), the sensitivity can go down to 10-7 ~10-8.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Other topicsSearch for hybrid charmonium, DD-bar molecular or other exotic states
BES-III will collect data at 3.773 GeV, 4.03 GeV and 4.14 (4.17) GeV, and perform finer cross section scans covering the resonances.
“Finer resonance line-shape analysis” provide an opportunity to search for heavy hybrid, DD-bar molecular, and four-quark states.
Fine cross sections scan
Analysis of the fine cross section scan data may probe new structures associated with hybrid charmonium, DD-bar molecular or other exotic states in this energy region…
If BEPC-II maximum energy can extend more than 4.2 GeV, that will be nice.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Measurements of the line-shapes of the cross sections for the exclusive processes:
,....cee ωη→−+
,.../,/,/,/ ' XJJJJee ψψηψηπψπ −+−+ →..., −+−+−+ → πϕπϕ KKee
..., )2,1,0()2,1,0( ωχρχ ==−+ → JcJJcJee
−+−+−+ → SS DDDDDDee ,,00
and comparing the line-shapes with these for the inclusive hadron production, one may find something new.
BES-II made finer cross section scan from 3.66 to 3.88 GeV, and studied the line-shapes of the inclusive hadron production, DD-bar production and some exclusive charmless final states production. But data sample is too small. We suggest that BES-III make the finer cross section scan covering the resonances with large samples to carefully study the structures.
2006-6-11 Gang RONG, IHEP, BES collaboration
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To measure the resonance parameters of ψ(3770) or ψ(3686), one had better to simultaneously fit ψ(3686) and ψ(3770) resonances, since there are strong correlations between the fitted parameters of the two resonances.
ψ(3770)
ψ(3686)
If one do not consider the effects of vacuum polarization corrections on the observed cross sections in the data reduction, the total width of ψ(3686)would decrease by about 40 keV!
ψ(3686)
hep-ex/0605107
Mainly due to vacuum polarization corrections
After subtraction of ψ(3686) , ψ(3770)and J/ ψ from the observed cross sections, one obtains the expected cross sections of the continuum hadron production.
2006-6-11 Gang RONG, IHEP, BES collaboration
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Precision measurementsSummary
BES-III can improve measurements on some important quantities: fD, fDs, form-factors or Vcs and Vcd. The accuracy level of measurements of fD and fDs can achieve ~2% with 20 fb-1 data. These quantities can be used to test or calibrate QCD technologies .
The accuracy level of measurements of non-leptonic charm Brs can achieve ~1% for D0 and D+ (~2.0% for D+
s ) with 20 fb-1 data.
New PhysicsBES-III can allow access to D0-D0bar mixing at ~2×10−4 and direct CP violations at ACP~ 5x10−3 with 20 fb-1 of data.
BES-III can allow access the rare decay at the sensitivity of 10−7.Using the data samples, we can measured the strong phase cos δD at the uncertainty level < 8%.
2006-6-11 Gang RONG, IHEP, BES collaboration
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SummaryMolecular charmonium & hybrid charmonium
With the data to be taken at 3.773 GeV and 4.030 GeV (or 4.160 GeV) with BES-III, we can search for molecular charmonium and hybrid charmonium, connecting with “fine” cross section scan data.
The start of data taking at BESIII promises an era of precise charm physics. BES-III will provide ~2% precision to calibrate LQCD calculations in D and Ds system.
The measurements from BaBar, Bell, CDF, D0, BTeV, CMS, ATLAS and LHC-b combining the precision LQCD calculations will produce a few per cent determinations of |Vub|, |Vcb|, |Vtd| and |Vts|, which allow us to approach the maximizing the sensitivity for probes for New Physics.
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Thank you 谢谢