Centennial APS Meeting Mats Selen, University of Illinois (speaking for the CLEO collaboration)
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Transcript of Centennial APS Meeting Mats Selen, University of Illinois (speaking for the CLEO collaboration)
APS Centennial
Centennial APS Meeting
Mats Selen, University of Illinois(speaking for the CLEO collaboration)
March 23, 1999
APS Centennial
This Presentation:
• New D0 mixing results – K mixing analysis (including lifetime)
(David Asner)– CP-even KK and lifetime results
(Tony Hill)
• Charmed Meson Spectroscopy– First observation of broad D1(j=1/2)
(Tim Nelson, Harry Nelson)
• B(c pK) absolute measurement– New method described– Preliminary results presented
(Dave Besson, Russ Stutz)
(Charge conjugation implied throughout)
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Our Detector:(CLEO-II & II.V)
Svx + HePr
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1996 1997 1998
32.3 pb-1
Our Accelerator(CESR)
9 fb-1
CLEO II.VIntegrated
Luminosity
DailyLuminosity
CLEO IItook 4.7 fb-1
prior to this
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Our Data:
On(2/3)Off(1/3)
This Presentation:
Mixing Analysis: 5.7 fb-1 CLEO-II.V (SVX)
DJ & c Analyses: 4.7 fb-1 CLEO-II
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0
0
*12
*12
*1212
0
0
22
22
D
D
iMiM
iMiM
D
D
t
00
00
DqDpD
DqDpD
H
L
1212
*12
*12
iM
iM
p
q
LHLH mmM
*
12*121212,
*12
*121212,
Re
Im
iMiMM
iMiMMm
HL
HL
Time evolution of D & D0 mesons
Decay eigenstates
Define
Where
Mixing Analysis:
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2y
Mx
What we are sensitive to in the K mixing analysis:
y
xyxRMIX
122
tan2
Where
D0 D0onshell
,KK…can be relatively
large in S.M.
D0 D0offshell
smallin S.M.
Window on New Physics
It will eventually be very important to disentangle “x” and “y”
CP eigenstate lifetime analysis will tellus about “y” independent of “x”
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RMIX =
)(
)(0
00
KDB
KDDBRMIX
D*+
D0
+
D0-
K+
D*+
D0
+
+
K-
“wrong-sign”
“right-sign”
But “wrong-sign” events can also come fromDoubly Cabibbo Supressed Decays (DCSD):
D*+
D0
+
-
K+
“wrong-sign”
Mixing in D0 K decays:
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D*+
D0
+
D0-
K+
Mixing
D*+
D0
+
-
K+
DCSD
1) Amplitudes evolve differently in time. 2) Amplitudes can interfere.
Can use timing information to help untangle Mixing from DCSD
Mixing vs DCSD:
Same initial & final states !• Bad news if this is all the info available• But theres more...
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The total “wrong-sign” rate is given by:
2
2cos2)( t
RtRRRetN MIX
MIXDCSDDCSDt
(Where t is measured in D0 lifetimes)
100% mixed100% DCSD
cos= 1cos= 0cos=-1
N(t)
D0 lifetimes
RMIX = RDCSD
RMIX / (RMIX+RDCSD)
(WS) (D0)
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Analysis uses excellent kinematic resolution tostop K-+ feedthrough, and relies on good Particle-ID to suppress backgrounds.
5.7 MeV
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RWS = (0.31 0.09 0.07) %
Systematic Errors
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CLEO-II 1
Aleph: RDCSD 1 RMIX 95% CL
E791Klv90%CL
E791 1
E691 90% CL
CLEO-II.5 1Preliminary
Results:
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Using Lifetime Info:
100% mixed100% DCSD
cos= 1cos= 0cos=-1
N(t)
D0 lifetimes
RMIX = RDCSD Exploit this info to limit RMIX
ws) = ( 0.650.4 (stat+sys) )x
D0)
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CLEO-II 1
Aleph: RDCSD 1 RMIX 95% CL
E791Klv90%CL
E791 1
E691 90% CL
CLEO-II.V 90% CLPreliminary
Mixing Results:
Limits have been calculated for all cos (ask me after)
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2y
Mx
What we are sensitive to in the K mixing analysis:
y
xyxRMIX
122
tan2
Where
D0 D0onshell
,KK…can be relatively
large in S.M.
D0 D0offshell
smallin S.M.
Window on New Physics
It will eventually be very important to disentangle “x” and “y”
CP eigenstate lifetime analysis will tellus about “y” independent of “x”
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CP-even Lifetime Analysis:
Look for (D0K-) (D0-K- K)
This is a direct measure of !(i.e. measure “y” independent of “x”)
Plan:Measure (D0K-)
(D0-) (D0K- K)
Both CP=+1Should have thesame lifetimes
D0K-D0-andD0K- Kare easy to distinguish kinematically
Don’t need particle-ID
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CP-even Yields:
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Lifetime Fits:
Use unbinned maximum likelihood fit toextract signal lifetimes:
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Extracting “y”:
Look for (D0K-) (D0-K- K)
12
Ky
Where + (-) are the CP even (odd) lifetimes,
and K = (+ + - )/2
Based on our present measurement:
y = -0.032 0.034or
-0.076 y 0.012 (90% CL)
CLEO II.V Preliminary
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Putting it all together
x
y
CLEO II.V Preliminary
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Future mixing prospects
CP odd eigenstatelifetime analysis
sneakpreview
Lots more data to analyze
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Charm Meson Spectroscopy
j=3/2
j=1/2
j=1/2
j=3/2
D1(j=1/2)D1(j=3/2)D2
*(j=3/2)
Previously not seen
Previously seen
D*+-
We search for
B- -
D0+
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• Analysis Technique– Partial reconstruction:
B- DJ0-; DJ
0 D*+-; D*+ D0
– Measure 4-momenta of .– Extract signal via 4-D Max Likelihood Fit
• Fitting Technique– 4 independent variables:
• helicity 2, helicity 3, azimuth ,D*
Fit parameters:Yields (3 resonant, 1 non-resonant)Mass and width of broad D1(j=1/2)Mixing and interference between resonances.Strong phases relative to D1(2420)
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Total Background
1+ d-wave 1+ s-wave 2+ d-wave
cos 3
vscos 2
vscos 2
vscos 1
cos 3
vscos 2
vscos 2
vscos 1
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Total background (see below)
D1(2420)0
D2*(2460)0
D01(j=1/2)
Fit Results
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1+ d-wave Weighted 1+ s-wave Weighted
2+ d-wave Weighted Background Weighted
Weighted Fit Components
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Preliminary Results
• Properties of D1(j=1/2)
MeV
MeVM
3626290
32102461101
79
41
34
With 5.7
significance
(second systematic error due to uncertainty modeling strong phases)
Spin-Parity assigned to 1+
Tests of JP favor 1+ over 0- (closest alternative).
Quark Model:
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B(c pK) Absolute• Why?
– One of the 4 measured quantities used to normalize all charm analyses
B(D0K-+),B(D+K-++),B(Ds+), B(cpK-+)
– Not well determined at present B(cpK-+) = (51.3)% PDG
• Our Technique (NEW):
e+ e-
c c
D*-
D -s
X e- e
p
c
Tag charm with one of these
pK-+
Baryon tag
Divide event into hemispheres
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Two versions:
c c D*-
D -s
X e- e
p
cpK-+
c c D*-
D -s
X e- e
p
canything
or
or
Triple correlation analysis (x2):
c cp
cpK-+
c c D*-
D -s
p
canything
anything
Double correlation analysis:
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Yield examples:
cpK-+
(same hemisphereas anti-proton tag)
D0K-+
(opposite hemispherefrom anti-proton tag)
(Double correlation analysis)
“numerator”
“denominator”
Apply efficiency correction and get answer...
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Sounds easy, but...Biggest Backgrounds/Corrections:
c c Dp
D N
Falsely increased denominator
Countc cp
D
anything
c c DD Falsely increased denominator
+ K-
Fake p tag
and correct
Study Kaon fake rate as a function proton momentum and correct (15% effect):
After correction,p momentum spectrumlooks OK.
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Preliminary Results
• Make the physics corrections mentioned on previous page (and other smaller ones):
• Make appropriate efficiency corrections.
B(cpK-+ )
Double correlation (4.9 0.5)%
Triple correlation (s tag) (5.2 1.3)%
Triple correlation (e tag) (5.6 2.5)%
Weighted average:
B(cpK-+ ) = (5.0 0.5 1.5) %
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Future ProspectsCLEO-III
• Several New Detector Components– RICH, Drift Chamber, Silicon
• New CESR cavities & IR– Lots more luminosity