Mats Selen, HEP-2005 1
Measuring Measuring Strong Phases, Strong Phases, Charm Mixing, Charm Mixing, and DCSD at and DCSD at
CLEO-cCLEO-c
Mats Selen, University of IllinoisHEP 2005, July 22, Lisboa, Portugal
Mats Selen, HEP-2005 2
CLEO-II.V (9/fb)
CLEO-III (14/fb)
CLEO-c (281/pb)
New RICHNew Drift Chamber
New siliconNew Trigger & DAQ
Replace siliconwith a wire
vertex chamber
CLEO Evolution
Mats Selen, HEP-2005 3
CLEO-c & D Tagging
Tag one D meson in a selected tag mode.Study decays of other D, (signal D)
e+e- (3770)DD Pure DD final state, no additional particles (ED = Ebeam). Low particle multiplicity ~ 5-6 charged particles/event Good coverage to reconstruct in semileptonic decays Pure JPC = 1 initial state
Targeted Analyses Mixing (x2+y2):DD(K-l+,(K-+)2
cos:Double Tag Events: K-+ vs CP± Charm Mixing (y): Flavor Tag vs CP± DCS: Wrong sign decays K-+ vs K-l+
Comprehensive AnalysisCombined analysis to extract mixing parameters, DCS, strong phase plus charm hadronic branching fractions
Analysis Preview
Charm Mixing, DCS, and cos impact naïve
interpretation of branching fraction analysisextension of Phys.Lett.B508:37-43,2001 hep-ph/0103110
Gronau/Grossman/Rosner & hep-ph/0207165 Atwood/Petrov
See Asner & Sun, CLNS 05/1923
e+ e
0D
0D
+
K+
Mats Selen, HEP-2005 4
Overview of fitting technique
# ( )Observed in tagged events( )
detection efficiency for ( ) #D tags
KB D K
K
Independent ofIndependent ofL and cross L and cross sectionsection
Single tags
D candidate mass (GeV)
Double tags
D K
,
D
D K
K
2 2| |BC beam DM E p
D candidate mass (GeV)
Dbeam EEE
Kinematics analogous to (4S)BB: identify D with
(MBC) ~ 1.3 MeV, x2 with 0
(E) ~ 7—10 MeV, x2 with 0
:D beamE E
15120±180 377±20
: 10 /D beam bc bcE E M M
56 pb-1 sample
56 pb-1 sample
Mats Selen, HEP-2005 5
(log scale)!
6 D+ Modes6 D+ Modes3 D0 Modes3 D0 Modes
2484±51(combine
d)
1650±42(combined)
Single tags Double tags
Global fit pioneered by Mark IIINDD & Bi’s extracted from single and double tag yields with 2 minimization technique.
D0 D0
D+ D+
i i iDDN N B ijjiDDij BBNN
ij ji
j ij
i j ij
DDij i j
NB
N
N NN
N
56 pb-1 sample
See Gao’s talk on CLEOhadronic branching fractionsmeasurement.
Mats Selen, HEP-2005 6
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 7
001
2
1DDD 00
22
1DDD
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
WR ii eAAeDKDKDKA
2
1
2
1 0011
Consider the amplitudes for these mass eigenstates decaying to :
WR ii eAAeDKDKDKA
2
1
2
1 0022
RiAe
WieA
WieA
A1
A2
i.e. the CP even & CP odd rates to a specific final state will not be the same !
In reality these are much shorter !
Mats Selen, HEP-2005 8
The rate for the CP even D1 to decay to is given by:
)cos(212
1
12
1
2
1
22
)()(2222
1
rrA
rererAeAAeA WRRWWR iiii
where WRA
Ar ,
Similarly, the rate for the CP odd D2 to decay to is given by:
)cos(212
1 222
2 rrAA
And to first order in r the asymmetry between CP even and CP odd taggedevents is given by:
rzrKDKD
KDKD
CPCP
CPCP
)cos(2
)()(
)()(
Measuring rate differences yields information about if we know r !!
Mats Selen, HEP-2005 9
If we do the math correctly (i.e. we don’t ignore mixing etc) then wefind that the rates will depend on the mixing parameters x and y aswell as on r and z.
By simultaneously measuring a collection of various rates we might expect to have enough constraints that all of the above can be (over) determined.
12 mmx
2
12y
CF
DCS
A
A
A
Ar
)cos(2 z
We consider flavor tagged final states f and f, CP tagged final states S+ and SAnd semileptonic final states l and l.
Reminder
Mats Selen, HEP-2005 10
What we learn from variousSingle and Double tag rates
Where f
fff zrAA 2 2/' xwyzy jjj 2/~ xwyzy jjj
From DDthresholdrunning
From DsD+s(DD)thresholdrunning
Biggest effects in CP ± 1final states
Big effect -show plots
)sin(2 w
Mats Selen, HEP-2005 11
KSK+K
Double tag yield for (K+K) vs (KSp0) = 40 events
Naïve expectation (LB)KK x (LB)Ks = 9.5 events
We see the predicted factor of 4 from (CP-)(CP+) constructive interference
Mats Selen, HEP-2005 12
CP tags are clearly very important…
CP+
D0
Note log scale
Mats Selen, HEP-2005 13
Even our dirtiest CP+ tag is not so bad…
Mats Selen, HEP-2005 14
Will use both 2 and 3-body CP- tags as well…
Example: D0KSK+K is mostly CP odd KS
Mats Selen, HEP-2005 15
Its also very important to do well with semileptonic modes…
Inclusive semileptonic decays versus K tags.
281 pb-1
Mats Selen, HEP-2005 16
Explore the sensitivity of this method using Monte Carlo
6105.300 DD
N
(The number of CP+ tags will limit the
statistical precision)
(Yield from 1 fb-1)
Mats Selen, HEP-2005 17
6105.300 DD
N (Yield from 1 fb-1)
110000
C
DD
C
DDNN
Better if world averagevalue for rK is used.
Mats Selen, HEP-2005 18
CombinedQC analysis
Summary• In correlated D0D0 system, use time-integrated single and double tag yields to probe mixing and DCS parameters
• “Targeted” analyses provide first measurement of cos 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()
Projections of CLEO-c Sensitivity