Y(5S): What has been Y(5S): What has been learned and what can learned and what can be learned be learned Steven Blusk Steven Blusk Syracuse University Syracuse University (on behalf of the (on behalf of the CLEO CLEO and Belle and Belle Collaborations) Collaborations) Introduction, and some B s Phenomenology Recent measurements at Y(5S) from CLEO & Belle B production studies B s rates: exclusive analyses B s rates: inclusive analyses Summary
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Y(5S): What has been learned and what can be learned
Y(5S): What has been learned and what can be learned. Introduction, and some B s Phenomenology Recent measurements at Y(5S) from CLEO & Belle B production studies B s rates: exclusive analyses B s rates: inclusive analyses Summary. - PowerPoint PPT Presentation
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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)
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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.
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
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What do we know about the Y(5S) ?What do we know about the Y(5S) ?
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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
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!
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)
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)
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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…