CLEO-c Workshop 1

Beyond SM Physics at a CLEO Charm Factory

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

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

CLEO-c Workshop 2

Data Assumptions

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

• Assume BaBar & Belle will (each) have 400 fb-1 on the Υ(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:

Two important benefits:• Flavor ID • Unambiguous Reconstruction

– 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)

0D

0D

K+

e-

e+

e−e+

π−

CLEO-c Workshop 4

Rare Decays

e+ e−

0D

0D

K+

π−

π0

e+

e-

Example Study: D0 → π0 e+e−

(∆C=1 Weak Neutral Current)

• In 32290 generic D0 decays:– 1098 D0 → K−π+ tags (εB=3.4%)– 1543 D0 → K−π+ π0 tags (εB=4.8%)

Tag using:D0 → K−π+ (B = 3.83%)D0 → K−π+π0 (B = 13.9%)

With just these two modes, εBtag=8.2%

Working Group: What is the tradeoff: efficiency vs cleanliness

CLEO-c Workshop 5

Tagged events …if we don’t properlyexclude tagged tracks

Ability to get rid of this stuff is a keyadvantage!

επee x εBtag= 1.5%

~ 500 evtNotag

CLEO-c Workshop 6

Suppose επee.εBtag= 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

CLEO-c B-fact

Simple spreadsheetanalysis tool available for working group.

For example…

CLEO-c Workshop 8

Some interesting examples:

1) B(D0 → γγ) - 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) Γ(D0 → ργ) / Γ(D0 → ωγ) (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

ργCLEO-II

ωγCLEO-II

CLEO-c Workshop 9

Mixing Phenomenology:

RiAeDK δ+− ≡π 0

D0

K−π+

DCS

CF

In hadronic decays:

MIXD0

WiAeDK δ+− ≡π 0

y = ∆Γ/2Γ (real)

D0 D0

K−

K+

W WD0 D0

x = ∆Μ/Γ (virtual)δ = δR–δW (important to measure)

r = A /A

CLEO-c Workshop 10

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

• Ultimately limited by Backgrounds & Systematics

Con

CLEO K3π analysis CLEO K*lν analysis

Pro

• Lots of data• Time evolution handle

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 ψ”(3770)

• Tagging !- Flavor known- All tracks accounted for

• Quantum Correlations- opens up new avenues of

search:

Pro

e+ e−

0D

0D

π−

K+

K+

π−

Con• No Time evolution handle:

D0’s produced ~at rest

• Can’t measure ∆Γ directly usinglifetime differences.

CLEO-c Workshop 13

e+ e−

0D

0D

π−

K+

K+

π−

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

( ) ( ) ( ) ( )[ ]p̂Dp̂D p̂Dp̂D2

1ψ 0000 −−−=INITIAL

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

(assumes CP conserved)

+

−−

+

+

+−

=Γ 222

222

21 11

11

21

11

11

21),(

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 likeDDγ

CLEO-c Workshop 14

0D

0D

π+

K-

K-

π+Interesting Case 1:

Ratio of Rates:

0D

0D

π−

K+

K-

π+

( ) terms smaller ++=ππΓππΓ

−++−

+−+−22

21

),(),( yx

KKKK

Useful for probing x & y

CLEO-c Workshop 15

Interesting Case 2:

Asymmetry =

0D

0D

π−

K+

K+

Κ−CP+ eigenstate

0D

0D

π−

K+

KS

ρ0CP- eigenstate

0D

0D

π−

K+

K+

Κ−CP+ eigenstate

0D

0D

π−

K+

KS

ρ0CP- eigenstate

Useful for probing r & δ= 2 r cos δ

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

CLEO-c Workshop 16

Another Example: D0 →K0π+π− Dalitz Plot Analysis to extract mixing parameters:

c

u

u

d

d

sdu

K0D0

π+

π−

K∗−

CF: D0 → K∗− π+

Mix or DCS: D0 → K∗+ π−Fit for these in Dalitzplot…

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

CLEO-c Workshop 17

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

See “wrong sign”decays at 5σ level.

See David Asner’s talk in beyond SM working group

CLEO-c Workshop 18

Yet another Example: D0 →π+π−π0 Dalitz Plot Analysis:

Also accessible from the D0 Interference !

D0 → π− ρ+

cu u

ddu

D0

ρ+

π−

D0 → ρ− π+

cu u

ddu

D0

π+

ρ−

D0 → π0 ρ0

c ddu ρ0

π0

u u

D0 → Κ0 π0

c sdu

Κ0

π0u u

D0 D0

CLEO-c Workshop 19

CLEO-II.V D0 →π+π−π0 Dalitz Plot Analysis (preliminary):

MD*-MD ρ+

ρ−

ρ0

KS

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

CLEO-c Workshop 20

Direct CP violation:

D

f

22

δieA11

δieANeed two paths frominitial D to final state f.

D

f

2*2

δieA1*1

δieA

Compare D → f to D → f

21 *2

*1

δδ += iif eAeAA

2121

δδ += iif eAeAA

CLEO-c Workshop 21

Direct CP violation:

)cos()Re(2)sin()Im(2

212*1

22

21

212*1

22

22

δ−δ++

δ−δ=

+

−=

AAAAAA

AA

AAA

ff

ffCPFind:

Good News: We know large strong phase differences (δ1− δ2) 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 ψ”(3770)

e+ e−

0D

0D

π−

π+

K+

Κ−

e+e− → ψ” → 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− π+ π0

CLEO-c Workshop 24

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

Find ACP = 0.031 ± 0.086

DPdDD

DD∫+

−= 22

22

00

00

MM

MMACP

D0 - D0 “Difference” Plot

Q: Are structural differences that integrate to zero interesting?

Better sensitivity to new physics expected in CS modes. Some are under investigation: D0 → K−Κ+ π0 and D0 → π− π+ π0

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

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/ψ → γ + (h,φ) may be sensitive to the compactification scale MS:

Rn ~ MP2MS

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

Look for

graviton or dilaton (undetected)

photonγ

J/ψ

h,φ

q

q

CLEO-c Workshop 27

If BR( J/ψ → γ + (h,φ) ) < 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: