Transcript Quantum Correlated Analysis

Measuring
Strong Phases,
Charm Mixing,
and DCSD at
CLEO-c
Mats Selen, University of Illinois
HEP 2005, July 22, Lisboa, Portugal
Mats Selen, HEP-2005
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CLEO Evolution
CLEO-II.V (9/fb)
New RICH
New Drift Chamber
New silicon
New Trigger & DAQ
CLEO-III (14/fb)
Replace silicon
with a wire
vertex chamber
CLEO-c (281/pb)
Mats Selen, HEP-2005
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CLEO-c & D Tagging
e+e- y(3770)DD
K+
 Pure DD final state, no additional particles (ED = Ebeam).
 Low particle multiplicity ~ 5-6 charged particles/event
 Good coverage to reconstruct n in semileptonic decays
 Pure JPC = 1- - initial state
Tag one D meson in a selected tag mode.
Study decays of other D, (signal D)
K-
D0
e-
e+
D0
p-
p+
Charm Mixing, DCS, and cosd impact naïve
interpretation of branching fraction analysis
extension of Phys.Lett.B508:37-43,2001 hep-ph/0103110
Gronau/Grossman/Rosner & hep-ph/0207165 Atwood/Petrov
See Asner & Sun, CLNS 05/1923
Mats Selen, HEP-2005
Analysis Preview
Targeted Analyses
Mixing (x2+y2):DD(K-l+n)2,(K-p+)2
 cosd:Double Tag Events: K-p+ vs CP±
 Charm Mixing (y): Flavor Tag vs CP±
 DCS: Wrong sign decays K-p+ vs K-l+n
Comprehensive Analysis
 Combined analysis to extract mixing
parameters, DCS, strong phase plus
charm hadronic branching fractions
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Overview of fitting technique
s(MBC) ~ 1.3 MeV, x2 with p0
Kinematics analogous to (4S)BB: identify D with s(E) ~ 7—10 MeV, x2 with p0
E  Ebeam - ED
ED  Ebeam : 10  d Mbc / Mbc
2
M BC  Ebeam
- | pD |2
Double tags
D   K -p p  ,
ED  Ebeam :
Single tags
56 pb-1
sample
D -  K p -p -
D  K -p p 
15120±180
377±20
D candidate mass (GeV)
Independent of
L and cross
section
Mats Selen, HEP-2005
56 pb-1
sample
D candidate mass (GeV)
# (K p -p - ) Observed in tagged events
B( D  K p p ) 
detection efficiency for (K p -p - )  #D tags
-

-
-
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Single tags
3 D0 Modes
Ni  NDD Bi i
6 D+ Modes
Double tags
Nij  N DD Bi B j ij
D0
N ij  j
2484±51
(combined)
D+
Bi 
N j  ij
N DD 
N i N j  ij
N ij  i j
56 pb-1
sample
1650±42
(combined)
(log scale)!
Global fit pioneered by Mark III
See Gao’s talk on CLEO
NDD & Bi’s extracted from single and double hadronic branching fractions
measurement.
tag yields with c2 minimization technique.
Mats Selen, HEP-2005
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It’s a feature, not a problem…
• The CLEO hadronic branching fraction
analysis did not include CP specific final
states since the quantum corrections to these
are not consistent with the simple fitting
approach used.
• If we take these effects into account properly
we will learn more !
– That’s the point of this talk.
Mats Selen, HEP-2005
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A simple way to understand what CP-tags can do for us:
For the moment, ignore CP violation and mixing and
write mass eigenstates D1 and D2 as
D1 

1
D0  D 0
2
)
D2 

1
D0 - D 0
2
)
Consider the amplitudes for these mass eigenstates decaying to K-p:
A2  K -p 


)
)


1
1
K -p  D 0  K -p  D 0 
Aeid R  A eidW
2
2
1
1
D2 
K -p  D 0 - K -p  D 0 
Aeid R - A eidW
2
2
A1  K -p  D1 
A1
A eidW
Aeid R
)
)
i.e. the CP even & CP odd
rates to a specific final state
will not be the same !
- A eidW
A2
Mats Selen, HEP-2005
In reality these are much shorter !
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The rate for the CP even D1 to decay to K-p is given by:
A1
2

)

)
1
1
id W 2
id R
 Ae  A e
 A2 1  r 2  re i (dW -d R )  re i (d R -dW )
2
2
1
A
 A2 1  r 2  2r cos(d ) where r  , d  d R - dW
2
A

)
Similarly, the rate for the CP odd D2 to decay to K-p is given by:
A2 
2

1 2
A 1  r 2 - 2r cos(d )
2
)
And to first order in r the asymmetry between CP even and CP odd tagged
K-p events is given by:
( DCP   K -p  ) - ( DCP -  K -p  )
 2r cos(d )  rz
- 
- 
( DCP   K p )  ( DCP -  K p )
Measuring rate differences yields information about d if we know r !!
Mats Selen, HEP-2005
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If we do the math correctly (i.e. we don’t ignore mixing etc) then we
find that the rates will depend on the mixing parameters x and y as
well as on r and z.
Reminder
m - m1
x 2

y
2 - 1
2
r
A ADCS

A ACF
z  2 cos(d )
By simultaneously measuring a collection of various rates we might
expect to have enough constraints that all of the above can be
(over) determined.
We consider flavor tagged final states f and f,
CP tagged final states S+ and SAnd semileptonic final states l and l-.
Mats Selen, HEP-2005
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What we learn from various
Single and Double tag rates
From
DD
threshold
running
Big effect show plots
Biggest effects in CP ± 1
final states
From
D-sD+s
(DDg,p)
threshold
running
Where
A   A2f rf z f
f
Mats Selen, HEP-2005
y 'j  z j y - w j x )/ 2
~y  z y  w x ) / 2
j
j
j
w  2 sin( d )
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K+K-
KSp0
Double tag yield for (K+K-) vs (KSp0) = 40 events
Naïve expectation (LB)KK x (LB)Ksp = 9.5 events
We see the predicted factor of 4 from (CP-)(CP+) constructive interference
Mats Selen, HEP-2005
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CP tags are clearly very important…
CP+
Note log scale
D0pp-
Mats Selen, HEP-2005
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Even our dirtiest CP+ tag is not so bad…
Mats Selen, HEP-2005
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Will use both 2 and 3-body CP- tags as well…
Example: D0KSK+K- is mostly CP odd KSf
Mats Selen, HEP-2005
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Its also very important to do well
with semileptonic modes…
281 pb-1
Inclusive semileptonic
decays versus Kp tags.
Mats Selen, HEP-2005
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Explore the sensitivity of this method using Monte Carlo
N D0 D 0  3.5 106
(Yield from 1 fb-1)
(The number of CP+
tags will limit the
statistical precision)
Mats Selen, HEP-2005
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N D0 D 0  3.5 106 (Yield from 1 fb-1)
N DC0D-10  N DC0D10
Better if world average
value for rKp is used.
Mats Selen, HEP-2005
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•
•
In correlated D0D0
system, use timeintegrated single and
double tag yields to
probe mixing and DCS
parameters
“Targeted” analyses
provide first
measurement of cosd
and improved limit on
RM
•
“Comprehensive”
analysis -Simultaneous
fit for hadronic and
semileptonic branching
fractions, mixing and
DCS parameters
•
Will be first direct
measurement of cos(d)
Mats Selen, HEP-2005
Summary
Projections of CLEO-c Sensitivity
Combined
QC analysis
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