Y(5S): What has been Y(5S): What has been learned and what can be learned and what can be

learnedlearnedSteven BluskSteven Blusk

Syracuse UniversitySyracuse University(on behalf of the (on behalf of the CLEO CLEO and Belle and Belle

Collaborations)Collaborations) Introduction, and some Bs Phenomenology Recent measurements at Y(5S) from CLEO & Belle

B production studies Bs rates: exclusive analyses Bs rates: inclusive analyses

Summary

22/28/28

IntroductionIntroductionThe The (5S)(5S) discovered by discovered by

CLEO & CUSB in 1985.CLEO & CUSB in 1985.

Massive enough to produce:Massive enough to produce:

Knowledge of Knowledge of BBss production at production at Y(5S)Y(5S) essential for essential for assessing the potential of assessing the potential of BBss physics at a high luminosity physics at a high luminosity ee++ee- - collider.collider.

A clean source of BA clean source of BSS decays is valuable to help interpret decays is valuable to help interpret New Physics found directly at the LHCNew Physics found directly at the LHC..

* * *

* * *

* * *

, , ,

, , , ,

, ,s s s s s s

BB BB B B

BB BB B B BB

B B B B B B

(5 ) (10.865 0.008) GeV

(110 13) MeV

Y SM

(5 )S

33/28/28

Why study the Y(5S) at Why study the Y(5S) at ee++ee-- Colliders?Colliders?

Clean source of Bs mesons

Absolute BF’s can be determined Inclusive & Exclusive Hadron collider only determines relative BF’s

Some decays of interest difficult for hadron machines. Information on can be obtained from untagged rates or time-integrated rates to CP eigenstates (BF’s) Modes with more than one neutral also difficult

44/28/28

CP eigenstates CP eigenstates

Time evolution (via Schrodinger Equation)Time evolution (via Schrodinger Equation)

BBss Mixing Phenomenology Mixing Phenomenology

1 1( ) ( ) ( ) , ( ) ( ) ( )

2 2S S

Even OS S S

ddSB t B t B t B t B t B t

11 12

21 22

11 12

21 22

M MM

M M

( ) ( )

( ) ( )S S

S S

B t B tdM i

dt B t B t

M12 contains the off-shell, short-distance physics, ie, q=t(sensitive to new physics, dominated by top quark loop in SM)

12 from on-shell states (q=c,u) accessible to both Bs and Bs.(less sensitive to NP, bccs tree diagrams dominant)

55/28/28

BBss Phenomenology, cont Phenomenology, cont

( ) ( ) ( ) , ( ) ( ) ( )L HS S S SB t p B t q B t B t p B t q B t

Allowing for CPV, weak eigenstates are:

Define:

Solve Schrodinger Equation:

1

2L H

Bs

L H

H Lm m m

12

12

2 cos

2m M

1212

12

arg arg( ) ~ 0.3oM

M

where in SM:

( ( ) ) cosh sinh cos( ) sin( )2 2

t CP CPS CP dir s mix sB t f e t A A m t A m t

One then obtains:

( ( ) ) cosh sinh cos( ) sin( )2 2

t CP CPS CP dir s mix sB t f e t A A m t A m t

For B0, ~0, and one recovers the familiar form:0( ( ) ) 1 cos( ) sin( )t CP CP

CP dir s mix sB t f e A m t A m t

2

2

1

1

fCPdir

f

A

2

2 Im

1

fCPmix

f

A

2

2 Re

1

fCP

f

A

0CPdirA sin 2CP

mixA For B0 J/Ks

ff

f

Aq

p A

212( ) ~ 1.5o

M Arg M

In SM, Mass Eigenstates should be ~ CP eigenstates, =CP, otherwise NP

66/28/28

BBss and CKM and CKM

But, ms~17 ps-1Oscillation length z ~ coscmfor Asymmetric B factorycompared to a z resolution of ~150 m No TD-CPV at Y(5S)

Bs decays provide an alternate probe from which to extract and the Bs mixing phase.

Bs J/J/, J/Measures Bs mixing phase J/, J/pure CP eigenstates; requires excellent photon reconstruction J/requires a time-dependent angular analysis:

Fit for ratio of CP amplitudes, ss and sin(2). (ss)~0.02 with 2 fb-1 at LHCb

Bs DsK Interference between direct tree and mixing + tree Measures sin() Likely insensitive to NP.

Caveat: Must be able to resolve the fast Bs oscillations for these measurements !!

77/28/28

@ Y(5S) @ Y(5S) Dunietz, Fleischer, & Nierstehep-ph/0012219 Some measurements only require

untagged time-dependent rates or time-integrated rates (BF’s)

For example, from lifetimes of CP (CP=1/CP) and flavor-specific final (FS=1/FS) states, one finds:

(2

) cos c s22

of

CPfC fP FS

Only measures product cos New physics can alter the mixing phase SMNP. NP unlikely in CP, since it’s dominated by trees

One can show that using BF’s:

,

2 ( ) evenCP s CP

f b ccs

B B f w

1 2

( )

( ) ( )

even oddCP CP

oddodd sCP even odd

s s

w x

B fx

B f B f

Where wf odd is a weight reflecting the relativeamount of CP even vs CP odd in f.

xx ww

00 11

0.50.5 00

1.01.0 -1-1

In the limit that intermediatestates are Ds

(*)+Ds(*)- and

all CP even, we get thefamiliar result that:

(*) (*)2 ( )CPs s sB B D D

Combining these two gives |cos|

88/28/28

Status of Status of ss Can use previously mentioned technique to get | cosCan use previously mentioned technique to get | cos|, but|, but

really need to measure BF’s really need to measure BF’s DDSS((**)+)+DDSS

((**)-)-, J/, J/, J/, J/etcetc (angular analysis for VV states to get CP even fraction).(angular analysis for VV states to get CP even fraction).

In the presence of NP In the presence of NP SMSMSMSM++NPNPNPNP

Measurements of Measurements of CPCP D0: 0.17D0: 0.17±0.09±0.03 & ±0.09±0.03 & CDF: CDF:

(statistically limited)(statistically limited) CPCP:: (B(BssKK++KK--)=1.53)=1.53±0.18±0.02 ps (CDF)±0.18±0.02 ps (CDF) CPCP: : B(DsB(Ds(*)+(*)+DsDs(*)-(*)-)=(7.1±3.5±2.7)%)=(7.1±3.5±2.7)%

These exclusive modes could be measured by a B-factory. These exclusive modes could be measured by a B-factory. See A. Drutskoy [hep-ph/0604061]See A. Drutskoy [hep-ph/0604061]

If there is a new physics phase then If there is a new physics phase then SM SM coscos; ; the Ds* modes difficult at LHCthe Ds* modes difficult at LHCbb because of the because of the from the from the DDSS* decay * decay B factories at Y(5S) can measure it…B factories at Y(5S) can measure it…

0.190.240.47 0.01

FPCP’06, R. Van Kootenhep-ex/0606005

99/28/28

What do we know about the Y(5S) ?What do we know about the Y(5S) ?

1010/28/28

Previous Data SamplesPrevious Data Samples

1985: Scans of Y(5S) region:1985: Scans of Y(5S) region:CLEO: 0.07 fbCLEO: 0.07 fb-1 -1 (on peak)(on peak)CUSB: 0.12 fbCUSB: 0.12 fb-1 -1 (on peak)(on peak)

CLEO PRL54 381, 1985

CUSB PRL54, 377, 1985

CUSB fit to modified potential model

Y(5S) Y(6S)?

Evidence for Bs production at Y(5S) inconclusive

1111/28/28

Recent Data Collected at the Recent Data Collected at the Y(5S)Y(5S)

20032003: CLEO collected 0.4 fb: CLEO collected 0.4 fb-1-1 on the Y(5S). on the Y(5S). Goals were:Goals were:Understand the composition of the Y(5S)Understand the composition of the Y(5S)Assess the physics potential of a B-factory Assess the physics potential of a B-factory

operating at the Y(5S)operating at the Y(5S)Measurements of BMeasurements of Bss decays. decays.

20052005: Belle collected about 1.86 fb: Belle collected about 1.86 fb -1-1 on on Y(5S)Y(5S)

20062006: Belle collected about 22 fb: Belle collected about 22 fb-1-1 on Y(5S) on Y(5S) (being processed)(being processed)

1212/28/28

Cross-Section MeasurementsCross-Section Measurements Count hadronic eventsCount hadronic events Subtract continuum from below-Y(4S)Subtract continuum from below-Y(4S)

Scale by ratios of luminosity, s=EScale by ratios of luminosity, s=Ecmcm22

Luminosity ratio significant source of systematic Luminosity ratio significant source of systematic error, error, since since (5S)~0.1(5S)~0.1(continuum), and 300 MeV below (continuum), and 300 MeV below Y(5S)Y(5S)

Cross-check Cross-check LL ratio using high momentum tracks ratio using high momentum tracks (0.6<p/p(0.6<p/pmaxmax<0.8)<0.8)

Results:Results: CLEO: CLEO: (5S)=(0.301±0.002±0.039) nb (5S)=(0.301±0.002±0.039) nb BELLE: BELLE: (5S)=(0.305±0.002±0.0016) nb (5S)=(0.305±0.002±0.0016) nb Remarkable agreement, Remarkable agreement, R~0.4R~0.4

PRL95, 261801 (1995)

hep-ex/0605110

1313/28/28

Separating Final StatesSeparating Final States

(*) (*)B B

*BB **BBBB

ssBB *ssBB **

ss BB

( )M B ( )sM B

MC* * *

* * *

, , ,

, , ,

BB BB B B

BB BB B B BB

Many final states accessibleat the Y(5S)

Photon from B*B not used.

B momentum contains sufficient information for kinematic separation.

All 2-body decays are kinematically separated from one another. The B(*)B(*)() are also separatedfrom the 2-body, but not well separated from each other.

Only for BB and BsBs does Mbc = M(B), M(Bs), respectively.

Biases from neglect of 50 MeV : B*B* : Mbc(B) = M(B*)+1.7 MeV Bs*Bs*: Mbc(Bs) = M(Bs*)+0.1 MeV

B beamE E E 2 2

Bbc BM E p

BB

1414/28/28

Ordinary B Mesons @ Y(5S) Phys. Rev. Lett.96:152001,2006 Reconstruct B mesons in 25

decay modes

BD(*)D(*) D0K, K0, K D+ K

JK+, JK*0, JKS

Invariant mass (GeV)

(1 ) 0.41 0.10 0.09s df f

BBX=(0.177±0.030±0.016) nb,

(5S)=(0.301±0.002±0.039) nb(5S)=(0.301±0.002±0.039) nb

1515/28/28

B Cross-Sections & BB Cross-Sections & BSS** Mass Mass

Production largest for B*B*, consistent Production largest for B*B*, consistent with models:with models:(B*B*)/(B*B*)/(BBX) = (74(BBX) = (74±15±8)%±15±8)%(BB*)/(BB*)/(B*B*) = (24±9±3)%(B*B*) = (24±9±3)%(BB)/(BB)/(B*B*) < 22% @ 90% cl(B*B*) < 22% @ 90% cl

BBSS* mass* massCompute Compute MMbcbc = M = Mbcbc(Bs*)-M(Bs*)-Mbcbc(B*)(B*)Largest systematic, beam energy scale Largest systematic, beam energy scale

cancelscancelsM = M = MMbcbc + 1.6 MeV (kinematic bias) + 1.6 MeV (kinematic bias)ObtainObtain

M(BM(BSS*)-M(B*)=(87.6±1.6±0.2) *)-M(B*)=(87.6±1.6±0.2) MeVMeV

Use precise B* mass to get M(BUse precise B* mass to get M(Bss*)*) M(BM(Bss*)=(5411.7 ± 1.6 ± 0.6) MeV*)=(5411.7 ± 1.6 ± 0.6) MeV

M(BM(BSS*)-M(B*)-M(BSS)=(45.7±1.7±0.7) )=(45.7±1.7±0.7) MeV MeV

Consistent, as expected from Consistent, as expected from Heavy Quark Symmetry with Heavy Quark Symmetry with M(B*)-M(B) =45.78±0.35 MeVM(B*)-M(B) =45.78±0.35 MeV

B*B*

BB*BB BB(*)

BB

CLEO

Project data onto Mbc axis

Fit for BB, BB*, and B*B* yieldsand <Mbc> for each.

B*B* peak gives the beam energycalibration ! 6.4±1.3 MeV from expected!

1616/28/28

Exclusive BExclusive Bss Analyses (CLEO) Analyses (CLEO)/ , /S sB J B J

s sB B

*s sB B

* *s sB B

(*)S SB D /

* *s sB B is dominant

* * 0.040.03( ) (0.11 0.02)nbs se e B B

*

* *+14s s-12

(B B )=(37 9)%

( (5 ))sBf

Y S

Phys. Rev. Lett.96:022002,2006

*SD , , ,SK K K K

4 cand.

10 cand.

1717/28/28

Exclusive BExclusive Bss Analyses (Belle) Analyses (Belle)

7 events in Bs* Bs*

3 events in Bs* Bs*

Bs Ds(*)+ -

Bs J/

Ds+ + ,

Ds+ K*0 K+,

Ds+ Ks K

+

9 events in Bs* Bs*

4 events in Bs* Bs*

Bs Ds+

Bs Ds*+

1818/28/28

Fits for BFits for BssBBss, B, BssBBss*, B*, Bss*B*Bss* (Belle)* (Belle)

Potential models predict Bs* Bs*dominance over Bs*Bs and BsBs

channels, but not so strong.

5.408< MBC<5.429 GeV/c2

Bs* Bs*

Nev=20.0 ± 4.8

6.7

5.384< MBC<5.405GeV/c2

Bs* BsBs Bs

5.36< MBC<5.38GeV/c2

Take slices in Mbc Project on E (all modes combined)

* *69(*) (*)

( )(94 )%

( )S S

S S

N B B

N B B

1919/28/28

Inclusive BInclusive Bss Analyses Analyses

Use inclusive particle yieldUse inclusive particle yield Choose a particle that has very different Choose a particle that has very different

decay rates from B & Bdecay rates from B & BSS Ex: DEx: DSS

5( (5 ) ) 2 ( ) (1 ) ( (4 ) )

S s s S Ss sB Y S D X N B B D X B Y Xf Df S

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

measure measureModel estimate based on quark level diagrams and measured ordinary B decay rates B(BS→DS X) =(92±11)%

Solve for fs

2020/28/28

ffss from D from Dss Yields (CLEO) Yields (CLEO)

Y(5S)Y(4S)Y(4S)

Y(5S)

continuum

6.73.4(16.8 2.6 )%sf

( ) (4.4±0.6)% SB D

x ( |p|/Ebeam )

Bra

nch

ing

Fra

ctio

n

,SUse D

Ds

B (BS→DS X) =(92±11)%

2121/28/28

ffss from D from Dss Yields (Belle) Yields (Belle)

Y(5S) Ds+

3775 ± 100 ev

points:5Shist: cont

After continuum subtraction and efficiency correction:

B(Y(5S) -> DsX) / 2 = (23.6 ± 1.2 ± 3.6) %

fs = (17.9 ± 1.4 ± 4.1 )%Nbb and BF(Ds)dominant uncertainties

B (Ds+) = (4.4 ± 0.6)% from PDG 2006

Drutskoy, et alhep-ex/0608015

2222/28/28

ffss from D from D00 Yields (Belle) Yields (Belle)

PDG 2006:

B(Bs D0X) = (8 ± 7) %Spectator model, ala

hep- ex/0508047 CLEO

B(B -> D0X) = (64.0 ± 3.0) %

B(D0 K-+) = (3.80 ± 0.07) %

After continuum subtraction and efficiency correction:

Bf (Y(5S) D0X) / 2 = (53.8 ± 2.0 ± 3.4) %

fs = (18.1 ± 3.6 ± 7.5 )%

Y(5S)

(55009 ± 510) evD0 -> K- +

points:5Shist: cont

Combining with Ds result: fs = (18.0 ± 1.3 ± 3.2 )%

Nbb dominant uncertaintiy

6.73.4: (16.8 2.6 )%sCLEO f

2323/28/28

Measurement of Measurement of ffSS Using Using Yields Yields

5( (5 ) ) 2 ( ) (1 ) ( (4 ) )

s ss sB Y S X N B Bf X B Y Sf X

Here we need B(BS → X)

Use CLEO-c inclusive yield measurements:

B(Do → X)=(1.0±0.10±0.10)%

B(D+ → X)=(1.0±0.10±0.20)%

B(DS → X)=(16.1±1.2±1.1)% (Preliminary [hep-ph/0605134 ], DsX updated)

From B(B → X) = (3.5±0.3)% find most of ’s arise from B→D→ & B→DS→

Predict that B(BS → X) = (16.1 ± 2.4)%

known

2424/28/28

Results on Results on ffSS Using Using Yields Yields

+11.0- 5.3 = (24.6±2.9 )%sf

Reconstruct Reconstruct KK++KK--

CLEO inclusive CLEO inclusive yields, for x<0.5, R yields, for x<0.5, R22<0.25<0.25

On Y(4S) On Y(5S)

Cont’m

Y(5S)

Y(4S), scaled

Continuum-subtracted spectra

2525/28/28

Summary of Summary of ffSS Measurements Measurements Plot shows statistical (dark Plot shows statistical (dark

line) line) & systematic errors added & systematic errors added linearlylinearly

Recall, model dependenciesRecall, model dependencies

A model-independent A model-independent approach, exploiting the large approach, exploiting the large difference difference in mixing between B and Bin mixing between B and Bss and and measuring like-sign and measuring like-sign and opposite sign leptons.opposite sign leptons.(Sia & Stone, hep-ph/0604021)(Sia & Stone, hep-ph/0604021)

Could also do a double-taggedCould also do a double-taggedanalysis, ala Mark III, CLEO-c.analysis, ala Mark III, CLEO-c.

(Both require large samples)(Both require large samples)

2626/28/28

Rare Exclusive BRare Exclusive Bss decays (Belle) decays (Belle)

K+K- DS(*)+DS

(*)-

Access to

2727/28/28

Expected Yields at Y(5S)Expected Yields at Y(5S)~100K Bs produced per fb-1 at Y(5S).

ModeMode ApproximateApproximate

ReconstructedReconstructedYield on 5SYield on 5S

(50 fb(50 fb-1-1))

LHCbLHCbExpectedExpected

ReconstructReconstructeded

Yield (2 fbYield (2 fb-1-1))

NotesNotes

BBssDDss 250250 80,00080,000

BBssJ/J/ 6060 100,000100,000

BBssDDssDDss

BBssDDssDDss

(*)(*)

BBssDDss(*)(*)DDss

(*(*))

5050

5050

5050

10,00010,000

??

??

BBssKK++KK-- 5050 37,00037,000

BBss 2-42-4 ?? BF = 10BF = 10-6 -6

(assumed)(assumed)

BBss 1010 9,0009,000 BF = 21x10BF = 21x10-6 -6

(assumed)(assumed)

O(10%) model-independent Bs BF’s would probably require several ab-1 at Y(5S)(my back of the envelope)

2828/28/28

SummarySummary More recent investigations of Y(5S):More recent investigations of Y(5S):

About 1/3 of Y(5S) produces BAbout 1/3 of Y(5S) produces Bss pairs, mostly B pairs, mostly Bss*B*Bss*.*. Ordinary B production dominated by B*B* (~2/3 of all B Ordinary B production dominated by B*B* (~2/3 of all B

production) production) Both consistent with coupled-channel model predictions, Both consistent with coupled-channel model predictions,

although Bs*Bs* rate appears higher than predictions (20 fbalthough Bs*Bs* rate appears higher than predictions (20 fb-1-1 sample from Belle should resolve this). sample from Belle should resolve this).

Precise BPrecise Bss* mass obtained from CLEO.* mass obtained from CLEO. Large mixing frequency makes time-dependent CPV Large mixing frequency makes time-dependent CPV

measurements inaccessible at Y(5S). This is where measurements inaccessible at Y(5S). This is where LHCLHCbb excels. excels.

Y(5S) data can provide some complementary Y(5S) data can provide some complementary information on information on to the time-dependent and time- to the time-dependent and time-integrated measurements at LHCintegrated measurements at LHCbb..

Results from ~20 fbResults from ~20 fb-1-1 Y(5S) sample from Belle should Y(5S) sample from Belle should be available early in 2007, stay tuned… be available early in 2007, stay tuned…

2929/28/28

BackupsBackups