CLEO-c Workshop 1

• Data Assumptions• Tagging• Rare decays• D mixing• CP violation• Off The Wall

Beyond SM Physics at a CLEO Charm Factory

(some food for thought)Mats Selen, UIUC, May/5/2001

CLEO-c Workshop 2

Data Assumptions

• Assume we will accumulate 3 fb-1 on the ”(3770)– 10 nb signal, 12 nb “other hadronic”:– About 3x107 DD pairs

• Assume BaBar & Belle will (each) have 400 fb-1 on the (4S)– 1.3 nb signal, 3 nb “other hadronic”– About 5x108 cc pairs each

• Our competition will have ~17 times more charm on ~33 times more “other hadronic” background.

CLEO-c Workshop 3

Big Advantage: Tagging:

– Suppose efficiency x BR (all tags) = 10% (more on this..)– Will have ~ 106 each tagged D0 and D+ per 1 fb-1

– Limits of order 10-6 possible from 3 fb-1 data (still pretty good)

e+ e

0D

0D

K+

e+

e-Two important benefits:• Flavor ID • Unambiguous Reconstruction

CLEO-c Workshop 4

• In 32290 generic D0 decays:– 1098 D0 K tags (B=3.4%)– 1543 D0 K tags (B=4.8%)

e+ e

0D

0D

K+

e+

e-

Tag using:D0 K (B = 3.83%)D0 K (B = 13.9%)

With just these two modes, Btag=8.2%

Working Group: What is the tradeoff: efficiency vs cleanliness

Example Study: D0 ee

(C=1 Weak Neutral Current)

Rare Decays

CLEO-c Workshop 5

ee x Btag= 1.5%

Tagged events

~ 500 evt

…if we don’t properly exclude tagged tracks

Ability to get rid of this stuff is a keyadvantage!

Notag

CLEO-c Workshop 6

Suppose ee.Btag= 1.5 %

Suppose we have 3 fb-1 (~1.5x107 D0D0 pairs)Suppose we see 0 events

90% CL upper limit is ~5 x 10-6

About a factor of 100 improvement over PDGin most cases.

Most modes studied were in the 10-6 10-5 range

Its hard to imagine BaBar/Belle would not be in the same ballpark,although based on simple scaling I think we have the edge inclean modes where they are background limited. See Excel Table

See Bruce Yabsley’s talk in beyond SM working group

CLEO-c Workshop 7

Simple spreadsheetanalysis tool available for working group.

For example…

CLEO-c B-fact

CLEO-c Workshop 8

Some interesting examples:

1) B(D0 - SM small: ~10-8 (Singer et. al. hep-ph/0104236) - good hunting for physics beyond SM. - no present limit, CLEO-c sensitivity ~ 10-6

2) D0 / D0 (Fajfer et. al. hep-ph/0006054)- Individual BR’s small: ~10-6 - Long distance effects cancel in ratio.- Ratio should be ~1 (30% deviation means new physics)

See Will Johns’talk in beyond SM working group

Presently:90% CL Upper Limits < 2.4x10-4

For both modes

CLEO-II

CLEO-II

CLEO-c Workshop 9

Mixing Phenomenology:

x = /(virtual)

RiAeDK 0

= R–W (important to measure)

r = A /A

D0

K

DCS

CF

In hadronic decays:

MIXD0

y = /2(real)

D0 D0

K

K

W WD0 D0

WiAeDK 0

CLEO-c Workshop 10

D0-D0 Mixing: At the Y(4S)

• Lots of data• Time evolution handle

Pro

• Ultimately limited by Backgrounds & Systematics

Con

CLEO K3 analysis CLEO K*l analysis

CLEO-c Workshop 11

Experimental Situation (May/2001)

x0 0.1 0.2

0

-0.1

0.1

y

CLEO-c Workshop 12

D0-D0 Mixing: At the ”(3770)

• No Time evolution handle: D0’s produced ~at rest

• Can’t measure directly using lifetime differences.

Con

• Tagging ! - Flavor known - All tracks accounted for • Quantum Correlations - opens up new avenues of search:

Pro

e+ e

0D

0D

K+

K+

CLEO-c Workshop 13

See hep-ph/0103110Gronau, Grossman & Rosner(and also working group tomorrow)e+ e

0D

0D

K+

K+

p̂Dp̂D p̂Dp̂D2

1ψ 0000 INITIAL

• The D0 and D0 are produced coherently in a JPC = 1 state.

(assumes CP conserved)

22

2

22

2

21 1

1

1

1

2

1

1

1

1

1

2

1),(

xyB

xyAff

02

01

02

01 DfDfDfDfA

02

01

02

01 DfDfDfDfB

• Time integrated decay rate to final state f1,f2: Looks slightlydifferent for C +initial states likeDD

CLEO-c Workshop 14

Interesting Case 1:0D

0D

K-

K-

0D

0D

K+

K-

terms smaller

22

2

1

),(

),(yx

KK

KK

Useful for probing x & y

Ratio of Rates:

CLEO-c Workshop 15

Asymmetry =

Interesting Case 2:

0D

0D

K+

K+

CP+ eigenstate

0D

0D

K+

KS

CP- eigenstate

There are several other interesting cases to study:See Jon Rosner’s & Alexey Petrof’s talks in beyond SM working group

0D

0D

K+

K+

CP+ eigenstate

0D

0D

K+

KS

CP- eigenstate

Useful for probing r & = 2 r cos

CLEO-c Workshop 16

Another Example: D0 K0Dalitz Plot Analysis to extract mixing parameters:

c

u

u

d

d

s

d

u

KD0

K

CF: D0 K +

Mix or DCS: D0 K Fit for these in Dalitzplot…

…along with other good stuff: other K*’s, K2, , , f0, f2…

CLEO-c Workshop 17

In CLEO II.V:Sensitivity to x & ywill be about 3%

See David Asner’s talk in beyond SM working group

See “wrong sign”decays at 5 level.

CLEO-c Workshop 18

Also accessible from the D0 Interference !

Yet another Example: D0 Dalitz Plot Analysis:

D0 +

cu u

dd

u

D0

D0 +

cu u

dd

u

D0

D0 0 c d

du

u u

D0 0 c s

du

u u

D0 D0

CLEO-c Workshop 19

At CLEO-c we will have 5-10x more events with no background

CLEO-II.V D0 Dalitz Plot Analysis (preliminary):

MD*-MD +

0

KS

CLEO-c Workshop 20

Direct CP violation:

Need two paths frominitial D to final state f.

D

f

22

ieA11

ieA

D

f

2*2

ieA1*1

ieA

Compare D f to D f

21 *2

*1

iif

eAeAA

2121

iif eAeAA

CLEO-c Workshop 21

Direct CP violation:

)cos()Re(2

)sin()Im(2

212*1

2

2

2

1

212*1

22

22

AAAA

AA

AA

AAA

ff

ff

CPFind:

Good News: We know large strong phase differences () are not uncommon in charm decays!This is an important ingredient.

Good/Bad News: Expect small weak phase differencesin Standard Model. SM ACP may be as big as 10-3 for some decay modes

Definitely a hunting ground for new physics.

CLEO-c Workshop 22

Observing this is evidence of CP

At the ”(3770)

e+ e

0D

0D

+

K+

e+e ” D0D0

JPC = 1

i.e. CP+

Suppose both D0’s decay to CP eigestates f1 and f2: These can NOT have the same CP :

CP(f1 f2) = CP(f1) CP(f2) (-1)l = CP

+ (since l = 1)

CLEO-c Workshop 23

CP violation in Dalitz Plots:

Example Search: D0 K + 0

CLEO-c Workshop 24

Fit D0 and D0 Dalitz Plots separately and look for asymmetries:

Find ACP = 0.031 0.086

DPd

DD

DD

22

22

00

00

MM

MMACP

D0 - D0 “Difference” Plot

Better sensitivity to new physics expected in CS modes. Some are under investigation: D0 K+ 0 and D0 + 0

This will be easier to do at a charm factorythan at Y(4S) due to backgrounds.

See Daniele Pedrini’stalk in beyond SM working group

Q: Are structural differences that integrate to zero interesting?

CLEO-c Workshop 25

General Observation

High statistics background free DalitzPlot analyses will be a great place to lookfor interesting physics at CLEO-c

Not only “Beyond SM”, also QCD etc..

CLEO-c Workshop 26

If time, end with something just for fun:Sensitivity to Large Extra Dimensions:

From Bijnens & Maul hep-ph/0006042

If there are n large extra dimensions the decay J/ + (h,) may be sensitive to the compactification scale MS:

Look for

graviton or dilaton (undetected)

photon

J/

h,

q

q

Rn ~ MP2MS

-(n+2)The size R of the extra dimension is given bywhere MP is the 4-dimensional Planck scale.

CLEO-c Workshop 27

If BR( J/ + (h,) ) < 10-5

we can set these lower boundson MS (as a function of n).

Predicted photon spectrum

CLEO-c Workshop 28

There is lots of interesting physics“Beyond the Standard Model” that

will be explored with CLEO-c

Find out more at tomorrows working group: