DPF-2006 1

Victor Pavlunin

on behalf of the CLEO Collaboration

DPF-2006

Results from four CLEO Y(5S) analyses:

Exclusive Bs and B Reconstruction at the Y(5S)

Inclusive Ds and Production at the Y(5S)

-

+

K- K+

:/JBs

DPF-2006 2

References:

Exclusive measurements: “Observation of Bs Production at the Y(5S) Resonance”, (CLEO collaboration) PRL

96, 022002 (2006)

“Measurements of the Exclusive Decays of the Y(5S) to B Meson Final States and Improved Bs

* Mass Measurement”, (CLEO Collaboration) PRL 96, 152001 (2006)

Inclusive Measurements: “Evidence for Bs

(*)Bs(*) Production at the Y(5S)”, (CLEO collaboration) PRL 95,

261801 (2005). [Includes a measurement of Ds production at the Y(5S)]

“Measurement of B (Y(5S) Bs(*)Bs

(*)) Using Mesons”, (CLEO Collaboration) hep-ex/0610035. Submitted to PRD. [Includes a measurement of production at the Y(5S)]

DPF-2006 3

Y(5S) Data Samples

CLEO I (1985): 0.12 fb-1

CLEO III (2003): 0.42 fb-1

BELLE (2005): 1.9 fb-1

BELLE (2006): ~20 fb-1

BABAR has not run at the Y(5S) [Note: ECM are different by several MeV for different data sets]

The topic of this talk

DPF-2006 4

CESR and CLEO

The CLEO detector was developed for B physics at the Y(4S). The CLEO-III configuration:

B-field: 1.5 T Gas (drift chamber): He and C3H8

Tracking: 93% of 4, P/P0.6% for a 1.0 GeV track Hadron particle ID: RICH (80% of 4) and dE/dx E/M crystal calorimeter: 93% of 4π, E/E 2.0%

(4.0)% for a 1.0 GeV (100 MeV) photon Muon prop. chambers at 3, 5 and 7 I .

The CLEO experiment is located at the Cornell Electron Storage Ring (CESR) operated in the region of the Upsilon resonances for over 20 years.

In 2003, we started collecting data at the (3770). Before that, we took a short run at the Y(5S).

DPF-2006 5

Introduction: Bs at the Y(5S) (1)

The Y(5S) resonance was discovered by CLEO and CUSB at CESR in 1985.

The Y(5S) is massive enough to decay into the following channels:

No evidence for Bs production at the Y(5S) was found in 116 pb-1 collected in1985.

Knowledge of Bs production at the Y(5S) is important for evaluating the potential of Bs physics at a high luminosity e+e collider (Super-B factory). Results from CLEO III studies of Bs production are the focus of this talk.

BBBBBBBBBBBBBB ,,,,,, ******

***,, ssssss BBBBBB

CLEOPRL 54, 381

(1985)

Y(5S)

MeVSGeVSM

total )13110())5(()008.0865.10())5((

DPF-2006 6

There are two papers that measure the hadronic cross section above the Y(4S) resonance:

CLEO: PRL 54, 381 (1985) CUSB: PRL 54, 377 (1985)

The cross section above the Y(4S) is described well by the Unitarized Quark Model (S.Ono et al., Phys.Rev.D 34, 186 (1986)).

The UQ model predicts:

Y(5S) B*B* or Bs*Bs

*, The Bs cross section is 1/3 of the Y(5S) cross

section. (e+ e- Y(5S)) 0.35 nb

Expect 150K of Y(5S) decays in the CLEOIII 0.42 fb-1 data sample, 1/3 of that are Bs

(*)Bs(*)

pairs.

Introduction: Bs at the Y(5S) (2)

ECM (GeV)

Curve: UQMData: CLEO

Y(5S)

DPF-2006 7

Y(5S) Cross Section Measurements

Count hadronic events at the Y(5S)

Subtract the continuum using data taken below the Y(4S)

Scale by ratios of luminosities and Ecm2

Luminosity ratio is a significant source of systematic errorsince (Y5S) ~ 0.1(continuum) and the continuum data are taken 300 MeV below the Y(5S)

Results:

[Y(5S)]=(0.301±0.002±0.039) nb

Consistent with theoretical predictions

Ref: hep-ex/0610035

DPF-2006 8

Exclusive B(s) Reconstruction at the Y(5S)

DPF-2006 9

An extension of B reconstruction technique used at the Y(4S) is employed to reconstruct Bs mesons at the Y(5S):

Continuum background suppression

variables (e.g., R2 = H2/H0)

Three decay channels of the Y(5S) to Bs mesons are possible:

Decay channel 1:

Decay channel 2:

Decay channel 3:

Overview of the Method (1)

beamBss EEBBSYs :)5(

beamBss EEBBSYs

*:)5( **

beamBbeamBss EEEEBBSYss ,:)5( *

*

22candidatebeambc PEM

beamcandidate EEE GeVsysstatMexhepCDF

BBBAssumption

MeVMMGeVM

PDG

Bs

ss

BsBs

Bs

))(0008.03660.5(:)0508022/(2005

%100)(:

)6.20.47()002.0370.5(

:2004

*

*

ss BB*ss BB

**ss BB

MC

DPF-2006 10

Overview of the Method (2) The Y(5S) can decay into a

variety of states with ordinary B mesons:

Large background from the continuum (e+e- qq) :

3.0~)(

)(:)4(

qqee

BBS

03.0~)(

)(:)5(

(*)(*)

qqee

BBS ss

BBBBBBBBBBBBBB

,,,,,,

***

***

A signal band for B mesons

A signal band for Bs mesons

)(BB*BB **BB

BB

ssBB *ssBB **

ss BB

)(BM )( sBM

MC

[The OFF Y(4S) and b data are used to model the continuum bkg]

[The ON Y(4S) data are used to model B bkg in the Bs analysis]

DPF-2006 11

Bs modes with a J/ Search for very clean modes having very large S/B ratio: BsJ/ , J/ and J/ ’. The J/ is reconstructed in the and ee channels. The following channels are used

for other particles: KK, , ()+-. Expect to find few signal events, assuming branching fractions similar to those for B

mesons. In the Y(5S) data, we find:

4 events in the signal box for Y(5S) Bs* Bs

*:3 events in Bs J/ 1 event in Bs J/

DATA DATA

The level of non-Bs background is 0.08 events at 68% CL in the Bs

*Bs* signal region.

The probability for 0.08 events to fluctuate to 4 events or more is PI 1.6 10-6

M(Bs*) =

5.4150 0.0018(stat) (GeV)

ss BB

*ss BB

**ss BB

DPF-2006 12

A Signal Event

KKJJBandBBBBSY

s

ssss

,/,/

,)5( ***

-

+

K- K+

DPF-2006 13

Bs modes with a Ds(*)-

Bs Ds(*) / with Ds modes given in the tables

MC predicts that a total of 10-14 events can be reconstructed in these channels In the Y(5S) data we find 10 signal candidates (including background):

The level of background is 1.8 events at 68% CL in the Bs

*Bs* signal

region.

The probability for 1.8 events to fluctuate to 10 events or more is PII 1.9 10-5

M(Bs*)=

5.41290.0012(stat) (GeV)

DATADATA

B0 branching fractions:

ss BB

*ss BB

**ss BB

DPF-2006 14

Results for Bs(*) Production

PI and PII are combined to obtain an overall probability for a background fluctuation [P = (PIPII)(1-ln(PIPII))]: P 8 10-10 (6).

All signal events correspond to Bs*Bs

* production. We set the following limits (90% CL):

and

Relating Bs branching fractions to B branching fractions, we find:

which is consistent with the theory (UQM): 1/3 of 0.30 - 0.35 nb of the total Y(5S) cross-section.

The mass of the Bs* meson is measured to be

16.0)(

)()(**

**

ss

ssss

BBee

BBeeBBee

16.0)(

)(**

ss

ss

BBee

BBee

nbsyststatBBee ss )](02.0)(11.0[)( 04.003.0

**

GeVsyststatBM s )](003.0)(001.0414.5[)( *

[for more information see: PRL 96, 022002 (2006)]

)]%(10)(35[))5(( 1211

** syststatBBSYB ss

DPF-2006 15

B modes with J/ and D(*)

Modes B D(*) / and B J/ K(*) (in total 25 modes):

E (GeV)

Mb

c (

GeV

)

MC Data

Note the non-standard definition of E in these plots (should have the opposite sign)

BB

*BB

** BB XBB

DPF-2006 16

Results for B(*) Production

B*B* is again dominant (consistent with models):

(B*B*)/(BBX) = (74±15±8)%(BB*)/(BBX) = (24±9±3)%(BB)/(BBX) < 22% at 90% CL

nbsyststatXBBee )](016.0)(030.0177.0[)(

nbsyststatBBee ss )](02.0)(11.0[)( 04.003.0

**

nbXBBee ss ]04.029.0[)( (*))(

(*))(

GeVsyststatBM s )](0006.0)(0016.04117.5[)( *

In combination with

gives

consistent with theory and exper.[for more information see: PRL 96, 152001 (2006)]

B*B*

BB*BB BB(*)

BB

(53 9) events

DPF-2006 17

Inclusive Ds and Measurements at the Y(5S)

DPF-2006 18

Overview of the Inclusive Method

The method relies on the fact that Ds (and ) mesons are produced more copiously in Bs decays compared to B decays.

Main Analysis Steps: Measure Ds yields (Ds +, K+K-) in bins of x = |PDs|/Ebeam in the

continuum, Y(4S) and Y(5S) data.

Measure B(Y(4S) DsX) and B(Y(5S) DsX) by subtracting properly scaled and normalized continuum yields from the Y(4S) and Y(5S) yields

Extract fs according to the equation above and account for systematic errors.

(*) (*)( (5 ) )s s sf B Y S B B

))4(()1()(2))5(( XDSYBfXDBBfXDSYB ssssss

measure measureModel dependent estimate:B(Bs Ds X) = (92 11) %

[B(Bs X) = (15 3) %]

DPF-2006 19

Results of the Inclusive Ds Method

))%()(6.28.16())5(( 7.64.3

(*)(*) syststatBBSYBf ssS

The largest sources of the systematic uncertainty are the uncertainty associated with the luminosity measurements the uncertainty in B(Ds).

Y(5S)Y(4S)

Y(4S)

Y(5S)

continuum

CLEO inclusive DS yields for x < 0.5 and R2<0.25

[for more information see: PRL 95, 261801 (2005)]

DPF-2006 20

Results of the inclusive method

CLEO inclusive yields for x < 0.5 and R2<0.25

))%()(9.26.24())5(( 0.113.5

(*)(*) syststatBBSYBf ssS

Y(5S)

Bra

nchi

ng F

ract

ion

Y(4S)

X = |P|/Ebeam

Y(4S)

Y(5S)

continuum

[for more information see: hep-ex/0610035

DPF-2006 21

Summary and ConclusionsUsing 0.42 fb-1 of data at the Y(5S) resonance, we obtain the following results: First observation of BS production at the Y(5S):

; and limits: and

First study of B production at the Y(5S): ;

Determination of Estimates of Bs production using inclusive

measurements of Ds and production at the Y(5S) (model dependent): Ds production: production:

Belle (using the 1.9 fb-1 sample) confirms CLEO results

nbsyststatBBee ss )](02.0)(11.0[)( 04.003.0

**

16.0)(

)(**

ss

ss

BBee

BBee

16.0)(

)()(**

**

ss

ssss

BBee

BBeeBBee

nbsyststatXBBee )](016.0)(030.0177.0[)(

1:1:3)(:)(:)( *** BBBBBB MeVBM s )6.06.17.5411()( *

)]%()(317[))5(( 73 syststatXBBSYB SS

)]%()(325[))5(( 115 syststatXBBSYB SS

)]%(10)(35[))5(( 1211

** syststatBBSYB ss

)]%(9)(1041[))5(( syststatXBBSYB SS

The Y(5S) resonance is a significant source of Bs mesons for a high luminosity e+e- collider

DPF-2006 22

Additional Slides

DPF-2006 23

Use CLEO-c inclusive yields (hep-ex/0610008) for

B(Do → X) = (1.0±0.10±0.10)% B(D+ → X) = (1.0±0.10±0.20)%

B(DS → X) = (15.1±2.1±1.5)%

Demonstrate that majority of mesons arise from B D and B DS .

Predict B(BS → X) = (14.9±2.9)%

Consult hep-ex/0610035 for details

Model estimate of B(BS → X)