CLEO-c and CESR-c: A New Frontier of Electroweak And QCD Physics

CLEO-c and CESR-c:

A New Frontier of Electroweak And QCD Physics

Kamal Benslama

Seminar at the University of Montreal November 14, 2002

CLEO-c

CLEO-c CESR-cCESR-c

D

D

, D

K



K^- K⁺

⁺

^

The CLEO Collaboration

Albany Caltech CMUCornell Florida Harvard Illinois Kansas Minnesota Ohio State Oklahoma Purdue Rochester SLACSMU

UCSDUCSB Syracuse Vanderbilt Wayne State

• Membership:

• ~20 Institutions

• ~155 physicists

• ~1/2 DOE, 1/2 NSF

• Currently expanding…

• Publication history 1980-

• ~320 papers

• diverse physics:

CESR

The CESR Storage Ring

The Storage Ring

Symmetric e⁺e^- accelerator at or near (4S)

(P_B ~ 300 MeV/ c)

On the (4S):

e⁺e^-  (4S) BB ( ~ 1 nb)

e⁺e^-  qq, (q = u, d, c, s) ( ~ 3 nb)

1/ 3 running at OFF (4S) for continuum bkg subtraction

CLEO III collected ON: 6.9 fb^-1

OFF: 2.3 fb^-1

- -

CESR and CLEO

What is CESR-c and CLEO-c ?

• Modify for low-energy operation:

wigglers

• Expected machine performance:

•  E

~ 1.2 MeV at J/ 

Ecm L ^{(1032 cm-2 s-1)}

3.1 GeV 2.0

3.77 GeV 3.0

4.1 GeV 3.6

One day scan of the ’:

(1/29/02)

1.5 T now,... 1.0T later 93% of 4

_p/p = 0.35% @1GeV dE/dx: 5.7%  @minI

93% of 4

_E/E = 2% @1GeV = 4% @100MeV

83% of 4

% Kaon ID with 0.2%  fake @0.9GeV

85% of 4

For p>1 GeV Trigger: Tracks & Showers

Pipelined

Latency = 2.5s

Data Acquisition:

Event size = 25kB Thruput < 6MB/s

CLEO III Detector

 CLEO-c Detector

CleoIII Tracking

 Silicon (r = 2 - 12 cm)

 4 Layers, double sided

 Suffering from rad damage

 Drift Chamber (DR) (r = 12 – 82 cm)

 47 anode layers, 9796 cells

 Inner part axial, outer part all stereo

Central Drift Chamber

• DK mass resolution ~ 5.5 MeV

• K_s mass resolution ~ 3.1 MeV

• _p/p = 0.35% @1GeV

• dE/dx: 5.7%  @minI

Average hit resolution 85 Sweet spot ~ 55-65

dE/dx in the Drift Chamber

•CleoIII dE/dx vs Momentum showing the , K and p bands.

•The K/ separation from dE/dx, in standard deviations.





Inner Tracking (2 < r < 12cm)

• Now: 4 Layer Silicon Detector

• Double sided wafers,

• 125000 channels

• 1.6% X₀ thickness

• early radiation damage:

Layers 1 & 2 r eff 

• Proposed: 6 layer drift chamber

• all stereo ( 10-15⁰ tilt)

• 300 channels: smaller evt size

• 1.1% inner wall + 0.1% gas

• improves _p/p (less material)

• worsens z₀ (stereo)

• preserves mass resolution

• no effect on pattern recognition

• build from spare parts

Silicon Radiation Damage

(rad)

• Efficiency losses exhibit wafer geometry, not detector geometry.

• rphi side only. Z side so far shows no eff loss.

Wire vertex Chamber

RICH Detector

Performance with Bhabhas (only RICH tracking):

single  resolution N_ resolution/track Flat radiator 14.0 mrad 10.2 5.3 mrad

Sawtooth radiator 12.2 mrad 12.0 4.2 mrad

Thinnest (19 cm) <0.12% X₀

Proximity Focusing

Solid Radiator (LiF)

45^o saw tooth outer face (40%)

Rest flat radiator

15.7 cm N Expansion Gap

MWPC photon detector

Photosensitive gas = TEA (Triethylamine)

_abs=0.5 mm, <165 nm

3  K/ separation at 2.65 GeV/c

RICH

Cherenkov Images

Flat radiators

Sawtooth

The RICH Smiles

e

e

e

e

PID using the RICH

 

 

































# 1

#

1

)

| (

)

| (

i

back i

signal i

back K

i signal K

P P

L

P P

L

•Likelihoods are defined as

where

- CB line shape (Gaussian with power law tail on the high side)

- constant

²_K²_= -2log(L_K/L_)

•Likelihood method folds in photon count and Cherenkov angle measurement

together

signal

P

Pback

Efficiency vs fakes study

•cut on 



•fit m(D

)

²_K ²_ x

²_K ²_

K



K



m_D0(GeV)/c²

Number of events

CsI Calorimeter

•93% solid angle coverage - uniform resolution in barrel & E.C.



/E = 4% @ 100 MeV 2% @ 1 GeV

•~5.5 MeV 

mass resolution

Typical Hadronic Event

(From online event display)

Look What RICH did to our Data !



Signal characteristics:

 Two stiff back-to-back particles

 Simple, robust analysis.

 Statistics limited, not systematics



Backgrounds:

 Entirely from “continuum”

 Continuum background characterized by event shape variables

CLEOIII Rare B Analysis



Continuum occasionally produces high momentum, back-to-back, 48%

35%K , 17%KK.



Roughly 25% from , 75% from , ,



Primary handle is in global event shape characteristics

π π π

d c d

c uu

s s

Signal Continuum

Spherical event 2-jets

Shape Structure

Continuum Background

Analyses Strategy



Study backgrounds (using Monte Carlo and OFF-resonance data)



Reconstructions variables



Maximum likelihood fit

PS:



Monte Carlo Experiments:

Study possible biases



Apply the fit to data

signal

continuum

 Energy difference

 Beam constrained mass

 ~ 2.5 MeV (3.0 MeV if ⁰ )

Resolution is mode

dependent, but generally

 ~ 20-25 MeV (2 worse if ⁰ )

2

| p | 

E 

M

_{E }

_E



_{ E }

 dE/dx  RICH

Reconstruction Variables

Signal is isotropic, continuum is jetty Use shape variables

 Sphericity angle

 R2 (Fox Wolfram moment)

 Momentum flow in nine cones around the sphericity axis

Combine the variables in a Fisher discriminant

Reconstruction Variables

N

N

^and are the yields to be determined

 PDF shapes for signal are determined from MC

 PDF shapes for continuum are determined from OFF-resonance data

Maximum Likelihood Method



Fit variables:



Fit component fractions:



Outputs:

plus background, at the maximum of the Likelihood function.

 Efficiency: Use of Maximum Likelihood fit doubles the efficiency of the analysis compared to a normal counting analysis

 Systematics

:

 Correlations: typically at few % level, except

- where kinematics leads to ~ 20%

correlation.

M

ΔE F

dx 2

dE 



 





cosθB

f

Nππ

dx 1

dE 



 





f

^f

NKπ N_KK

ΔE _M

Maximum Likelihood Fit

3 . 1 8

. 18 6

. 18 2

.

29 ^_6^7._.¹₄ ^_⁴_4.^.₁⁵_^₃³_.^.₄^{0 }_2²_.^.₆⁸ 

Yield BR(BK)(x10^-6) BK CLEOIII CLEO(1999)

Good agreement: between CLEOIII & CLEO II &

with BaBar/Belle.

How well does CLEO III work?

1

results from CLEO III data at Lepton-photon

2001

FINAL Results VERY Soon

The CLEO-c Program

20 02

20 03

20 04

20 05

Prologue: Upsilons ~1-2 fb^-1 ea.

Y(1S) ,Y(2S), Y(3S)…

Spectroscopy, Matrix Elements, _ee

10-20 times existing world’s data

Act I: (3770) -- 3 fb^-1

30M events, 6M tagged D decays

(310 times MARK III)

Act II: √s ~ 4100 -- 3 fb^-1

1.5M D_sD_s, 0.3M tagged D_s decays

(480 times MARK III, 130 times BES II )

Act III: (3100) -- 1 fb^-1 1 Billion J/ decays

(170 times MARK III 20 times BES II)

•Charm events produced at

threshold are extremely clean

•Large , low multiplicity

•Pure initial state: no fragmentation

•Signal/Background is optimum at threshold

•Double tag events are pristine

–These events are key to making absolute branching fraction

measurements

•Neutrino reconstruction is clean

•Quantum coherence aids D mixing and CP violation studies

Why run on threshold Resonances ?

A typical Y(4S) event:

Tagging Technique

•

Pure DD or D

D

production

 Many high branching ratios (~1-10%)

 High reconstruction eff

 Two chances

 high net efficiency ~20% !

D  K tag.

S/B ~ 5000 D_s  KK tag.

S/B ~ 100

Beam constrained mass

6M D tags 300K D_s tags 6M D tags

300K D_s tags

• We expect great advances in flavor and electroweak physics during the next decade:

– Tevatron (CDF, D0, BTeV,CKM).

– B-Factories (BaBar, Belle).

– LHC (CMS, ATLAS, LHC-b).

– Linear Collider (?).

• What could CLEO-c possibly have to offer this program?

Why CLEO-c ? Why Now ? Why CLEO-c ? Why Now ?

To score nice goals we

Absolutely need an excellent player who can make the Perfect passes at the perfect time

CLEO-c

Precision Standard Model Tests

f

and f

at ~2% level

Absolute hadronic charm branching ratios with 1- 2% errors.

Semileptonic decay form-factors (few % accuracy).

Contribution to CKM

Measurements

Absolute Branching Ratios

~ Zero background in hadronic modes

Decay Mode PDG2000 CLEOc (B/B %) (B/B %)

D⁰

 K  2.4 0.5

D

 K  7.2 1.5

D

 25 1.9

Set absolute scale for all heavy quark meas.

The importance of absolute Charm BRs

Stat: 3.1% Sys 4.3% theory 4.6%

Dominant Sys: _slow, form factors

& B(DK) dB/B=1.3%

V

from zero recoil in B  ^D* 



CLEO LP01

10

) 1 . 2 0

. 2 4

. 1 4

. 46

(    

cb



V

Decay Constants : ^|f

^|

^|V

^|

D_s  

D  

 f

s

f

 2.1%

 ^f

f

 2.6%

K_L





(Now: ±35%)

(Now: ±100%)





Br(D_s  ^



Importance of measuring f

& f

: Vtd & Vts

1

2

3 2

1

10 8 . 8 50 200

.

0 



 





 











 

 _d ^{ B B} V^td _

MeV f ps B

M ^{d d}

d d

B B

B B

d d

B f

B f

M

M ) ( )

5 ( . ) 0

(

 









 

1.8% ~15%

Lattice predicts f_B/f_D & f_Bs/f_Ds with small errors

if precision measurements of f_D & f_Ds existed (they do not)

could substitute in above ratios to obtain precision estimates of f_B

& f_Bs and hence precision determinations of Vtd and Vts Similarly f_D/f_Ds checks f_B/f_Bs

(lattice)

2 2























 





ts td B

B B B s

d

V V f

B f B M

M

s s

d d







  i



 1

  i

1

~5% (lattice)

COMPARISON

0 5 10 15 20 25 30

Error (%)

f

) K

D (

Br ^  

) D

(

Br _S  

) K D

(

Br ⁰  

BaBar 400 fb^-1 Current

Comparison between B factories & CLEO-C

Systematics &

Background limited

CLEO-c

3 fb^-1 Statistics limited

abcdefghi

f

|f(q²)|²

|V_CKM|²

Absolute magnitude & shape of form factors is a great test of theory.

b

c

u

d HQET

l 

l 

1) Measure D form factor in Dl (CLEO-c): Calibrate LQCD to 1%.

2) Extract V_ub at BaBar/Belle using calibrated LQCD calc. of B form factor^.

3) Precise (5%) V_ub is a vital CKM cross check of sin2.

4) Absolute rate gives direct measurements of V_cd and V_cs.





B

D i.e.

Semileptonic Form Factors. Semileptonic Form Factors.

2 2 2 3

2 2

2

( )

24 G V P f q dq

d

K F cs







Semileptonic Decays ^|V

^|

^|f(q

^)|

Decay Mode PDG2000 CLEOc (B/B %) (B/B %)

D⁰ Kl 5 1.6

D⁰ l 16 1.7

D⁺ l 48 1.8

D_s l 25 2.8

Plus vector modes...

U = E_miss - P_miss LowBkg!







































































































e e D

e K D

e K D

e D

e D

e K D

e K D

e D

e D

e K D

e K D

c s

s s

: 12

: 11

: 10

: 9

: 8

: 7

: 6

: 5

: 4

: 3

: 2

: 1

0

* 0 0 0 _

0

* _

0 0

0

* 0

0

Semileptonic dB/B, Vcd, & Vcs Semileptonic dB/B, Vcd, & Vcs

0 10 20 30 40 50 60 70 80 90 100

1 2 3 4 5 6 7 8 9 10 11 12

Decay modes

Error (%)

CLEOc PDG

Vcs /Vcs = 1.6% (now: 11%) Vcd /Vcd = 1.7% (now: 7%)D⁰  K ^e^







 e D⁰

Use CLEO-c validated lattice + B factory Blv for ultra precise Vub

D⁰ l

D⁰ Kl

How can CLEO-c Contribute to CKM Measurements ?

An illustration using a variant of the 95% Scan method.

Allowed regions of the - plane using:

 ^

• current experimental results and

• conservative theoritical uncertainties

Allowed regions of the - plane using:

• current experimental results and

• theoritical uncertainties of O(1%)

•2% decay constants and 3% semileptonic form factors

 ^

CLEO-c: Probes of new Physics

Mixing sensitivity at the 1% level.

CP violation sensitivity at the 1-2% level.

•

Rare Decays.

D0

D0

^ K^-

K^-

^

D0

D0

^ K⁺

K^-

^

Ratio of Rates:

Charm Mixing Charm Mixing

x = /

y = /2

To 1^st order, where

e⁺e^  ”  D⁰D⁰

NO DCSD

Quantum coherence

At the (3770)

e⁺ e^

D0

D0

^

⁺

K⁺

^

e⁺e^  ”  D⁰D⁰

J^PC = 1^

i.e. CP+

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

CP Violation CP Violation

Observing this is evidence of CP

Ex:

(K

K

)(π

π

)

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

+ (since l = 1)

Compare to B Factories

CLEO-C BaBar Current

2-4fb-1 400 fb-1 Knowledge

f_D |Vcd| ^{1.5-2% 10-20% n.a.}

f_Ds |Vcs| ^{<1% 5-10% 19%}

Br(D+ -> ) 1.5% 3-5% 7%

Br(Ds -> ) 2-3% 5-10% 25%

Br(D->l) 1.4% 3% 18%

Br(c -> p) 6% 5-15% 26%

A(CP) ^{~1% ~1% 3-9%}

x'(mix) ^{0.01 0.01 0.03}

Systematics & background limited.

Statistics limited.

•  and  Spectroscopy

–Masses, spin fine structure –Leptonic widths for S-states.

–EM transition form factors

•run on  resonances winter ’01-summer’02

•~ 4 fb^-1 total

Uncover new states of matter

Glueballs G=|gg  Hybrids H=|gqq 

Requires detailed understanding of ordinary hadron spectrum in 1.5-2.5 GeV mass range.

Study fundamental states of the theory

Calibrate and test theoretical tech.

Probing QCD

•Gluons carry color charge: should bind!

• But, like Elvis, glueballs have been sighted too many times without confirmation....

• CLEO-c: find it or debunk it!

 huge data set

 modern detector

 95% solid angle coverage

• Radiative  decays are ideal glue factory:

Gluonic Matter

X

 c

c¯

• CLEO-c: 10⁹ J/  ~60M J/ X

• Partial Wave analysis

• Absolute BF’s: ,KK,pp,,…

1

• perfect initial state

• perfect tag

• glue pair in color isosinglet

The dubious life of the f

(2220) (A case study)

Now you see it…

(1996)BES MARKIII

(1986)

L31997

Now you don’t…

Crystal barrel:

pp

?? LEAR

1998

OPAL1998

L3 Signal

2 3

M_KK

2 3

… or do you?

… or don’t you?

f

(2220) in CLEO-c?

f

(2220) in CLEO-c?

Two Photon Data: fJ2220

– CLEO II: B fJ /KSKS < 2.5(1.3) eV – CLEO III: sub-eV sensitivity

Upsilonium Data: (1S): Tens of events

5000 –



8500 32

pp

5300 23

KSKS

18600 46

K⁺K^-

13000

^^ 18

32000

^^ 74

CLEO-C BES

CLEO-c has corroborating checks:

2

3

Inclusive Spectrum J/   X

10^-4 sensitivity for narrow resonance Eg: ~25% efficient for f_J(2220)

Suppress hadronic bkg: J/^X

Additional topics

• ’ spectroscopy (10 ⁸ decays) ^’_ch_c…

•





at threshold (0.25 fb

)

• measure mto ± 0.1 MeV

• heavy lepton, exotics searches

• 



at threshold (1 fb

)

• calibrate absolute BR(



• R=  (e

e

 hadrons)/  (e

e

 



)

• spot checks

If time permits Likely to

be added to run plan

-

The CLEO-c Program: Summary

•

• 20-500 times bigger than previous experiment

•

•Experienced Collaboration

•

Powerful physics case

• Precision flavor physics -

• Nonperturbative QCD -

• Probe for New Physics

•

•Very small and well-understood systematic errors

• A large number of and wide variety of precision measurements to challenge and validate theory

CLEO-c Physics Impact

•CLEO-C workshop (May 2001) : successful ~120 participants, 60 non-CLEO

•Snowmass working groups E2/P2/P5 : acclaimed CLEO-c

• HEPAP endorsed CLEO-c

•CESR/CLEO Program Advisory Committee Sept 28 Endorsed CLEO-c

•Proposal submission to NSF was on October 15,2001

•Site visit on Jan/Feb 2002: Endorsed ^CLEO-c

•Science Board March 2002,

• Expect approval shortly thereafter

•See http://www.lns.cornell.edu/CLEO/CLEO-C/

for project description

Invitation

If interested in CLEO-c program you are more

than welcome to join my ex-colleagues. They have room for you !

More information is available in CLEO Web page: www.lns.cornell.edu/CLEO/CLEO-c

Contact person: spoke@mail.lns.cornell.edu

CLEO-c

CLEO-c CESR-cCESR-c

Glueball Spectrum