Measuring Strong Phases, Charm Mixing, and DCSD at CLEO-c

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Measuring Strong Phases, Charm Mixing, and DCSD
at CLEO-c
Mats Selen, University of IllinoisHEP 2005, July
22, Lisboa, Portugal
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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 siliconwith a wire vertex chamber
CLEO-c (281/pb)
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CLEO-c D Tagging

• 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)

Analysis Preview

• Targeted Analyses
• Mixing (x2y2)DD?(K-ln)2,(K-p)2
• cosdDouble Tag Events K-p vs CP
• Charm Mixing (y) Flavor Tag vs CP
• DCS Wrong sign decays K-p vs K-ln
• Comprehensive Analysis
• Combined analysis to extract mixing
• parameters, DCS, strong phase plus
• charm hadronic branching fractions

Charm Mixing, DCS, and cosd impact naïve
interpretation of branching fraction
analysis extension of Phys.Lett.B50837-43,2001
hep-ph/0103110 Gronau/Grossman/Rosner
hep-ph/0207165 Atwood/Petrov See Asner Sun,
CLNS 05/1923
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Overview of fitting technique
s(MBC) 1.3 MeV, x2 with p0 s(DE) 710 MeV, x2
with p0
Kinematics analogous to ?(4S)?BB identify D with

Double tags
56 pb-1 sample
Single tags
56 pb-1 sample
15120180
37720
D candidate mass (GeV)
D candidate mass (GeV)
Independent of L and cross section
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Single tags
Double tags
6 D Modes
3 D0 Modes
D0
248451 (combined)
56 pb-1 sample
D
165042 (combined)
(log scale)!
Global fit pioneered by Mark III NDD Bis
extracted from single and double tag yields with
c2 minimization technique.
See Gaos talk on CLEOhadronic branching
fractionsmeasurement.
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Its 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 !
• Thats the point of this talk.

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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
Consider the amplitudes for these mass
eigenstates decaying to K-p
A1
i.e. the CP even CP odd rates to a specific
final state will not be the same !
A2
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
where
Similarly, the rate for the CP odd D2 to decay to
K-p is given by
And to first order in r the asymmetry between CP
even and CP odd taggedK-p events is given by
Measuring rate differences yields information
about d if we know r !!
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If we do the math correctly (i.e. we dont ignore
mixing etc) then wefind that the rates will
depend on the mixing parameters x and y aswell
as on r and z.
Reminder
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 S- And
semileptonic final states l and l-.
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What we learn from variousSingle and Double tag
rates
From DDthresholdrunning
From D-sDs(DDg,p)thresholdrunning
Where
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KSp0
KK-
Double tag yield for (KK-) vs (KSp0) 40 events
Naïve expectation (LeB)KK x (LeB)Ksp 9.5 events
We see the predicted factor of 4 from (CP-)(CP)
constructive interference
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CP tags are clearly very important
CP
Note log scale
D0?pp-
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Even our dirtiest CP tag is not so bad
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Will use both 2 and 3-body CP- tags as well
Example D0?KSKK- is mostly CP odd KSf
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Its also very important to do well with
semileptonic modes
281 pb-1
Inclusive semileptonic decays versus Kp tags.
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Explore the sensitivity of this method using
Monte Carlo
(Yield from 1 fb-1)
(The number of CP tags will limit the
statistical precision)
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(Yield from 1 fb-1)
Better if world averagevalue for rKp is used.
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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
  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)

Projections of CLEO-c Sensitivity