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

Measuring Strong Phases, Charm Mixing, and DCSD at CLEO-c. Mats Selen, University of Illinois HEP 2005, July 22, Lisboa, Portugal. 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.

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

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  1. Measuring Strong Phases, Charm Mixing, and DCSD at CLEO-c Mats Selen, University of IllinoisHEP 2005, July 22, Lisboa, Portugal

  2. 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)

  3. e+e-y(3770)DD K+ K- e- e+ p- p+ 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 (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 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

  4. Overview of fitting technique s(MBC) ~ 1.3 MeV, x2 withp0 s(DE) ~ 7—10 MeV, x2 withp0 Kinematics analogous to (4S)BB: identify D with Double tags 56 pb-1sample Single tags 56 pb-1sample 15120±180 377±20 D candidate mass (GeV) D candidate mass (GeV) Independent of L and cross section

  5. Single tags Double tags 3 D0 Modes 6 D+ Modes D0 2484±51 (combined) 56 pb-1sample D+ 1650±42 (combined) (log scale)! Global fit pioneered by Mark III NDD & Bi’s extracted from single and double tag yields with c2 minimization technique. See Gao’s talk on CLEOhadronic branching fractionsmeasurement.

  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.

  7. A simple way to understand what CP-tags can do for us: For the moment, ignore CP violation and mixing and write mass eigenstatesD1andD2as Consider the amplitudes for these mass eigenstates decaying toK-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 !

  8. 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 !!

  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. 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+ andl-.

  10. Big effect -show plots Biggest effects in CP ± 1final states What we learn from variousSingle and Double tag rates From DDthresholdrunning From D-sD+s(DDg,p)thresholdrunning Where

  11. K+K- KSp0 Double tag yield for (K+K-) 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

  12. CP tags are clearly very important… CP+ Note log scale D0p+p-

  13. Even our dirtiest CP+ tag is not so bad…

  14. Will use both 2 and 3-body CP- tags as well… Example: D0KSK+K- is mostly CP odd KSf

  15. Its also very important to do well with semileptonic modes… 281 pb-1 Inclusive semileptonic decays versus Kp tags.

  16. Explore the sensitivity of this method using Monte Carlo (Yield from 1 fb-1) (The number of CP+ tags will limit the statistical precision)

  17. (Yield from 1 fb-1) Better if world averagevalue for rKp is used.

  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 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

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