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