Y(5S): What has been learned and what can be learned Steven Blusk Syracuse University (on behalf of the CLEO and Belle 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

2/28Introduction The  (5S) discovered by CLEO & CUSB in The  (5S) discovered by CLEO & CUSB in Massive enough to produce: Massive enough to produce: Knowledge of B s production at Y(5S) essential for assessing the potential of B s physics at a high luminosity e + e - collider. Knowledge of B s production at Y(5S) essential for assessing the potential of B s physics at a high luminosity e + e - collider. A clean source of B S decays is valuable to help interpret New Physics found directly at the LHC. A clean source of B S decays is valuable to help interpret New Physics found directly at the LHC.

3/28 Why study the Y(5S) at e + e - Colliders?  Clean source of B s 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

4/28 CP eigenstates CP eigenstates Time evolution (via Schrodinger Equation) Time evolution (via Schrodinger Equation) B s Mixing Phenomenology M 12 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 B s and B s. (less sensitive to NP, b  ccs tree diagrams dominant)

5/28 B s Phenomenology, cont  Allowing for CPV, weak eigenstates are:  Define:  Solve Schrodinger Equation: where in SM:  One then obtains: For B 0,  ~0, and one recovers the familiar form: For B 0  J/  K s  In SM, Mass Eigenstates should be ~ CP eigenstates,  =  CP, otherwise NP

6/28 B s and CKM But,  m s ~17 ps -1 Oscillation length  z ~  c  osc  m  for Asymmetric B factory compared to a z resolution of ~150  m  No TD-CPV at Y(5S)  B s decays provide an alternate probe from which to extract   and the B s mixing phase.  B s  J/  J/ , J/    Measures B s mixing phase  J/ , J/  pure CP eigenstates; requires excellent photon reconstruction   J/  requires a time-dependent angular analysis:  Fit for ratio of CP amplitudes,  s  s and sin(2  ).   (  s  s )~0.02 with 2 fb -1 at LHC b  B s  D s K  Interference between direct tree and mixing + tree  Measures sin(  )  Likely insensitive to NP. Caveat: Must be able to resolve the fast B s oscillations for these measurements !!

7/28 Y(5S) Dunietz, Fleischer, & Nierste hep-ph/  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:  Only measures product  cos   New physics can alter the mixing phase    SM  NP.  NP unlikely in  CP, since it’s dominated by trees  One can show that using BF’s: Where w f odd is a weight reflecting the relative amount of CP even vs CP odd in f.xw In the limit that intermediate states are D s (*)+ D s (*)- and all CP even, we get the familiar result that: Combining these two gives |cos  |

8/28 Status of  s Can use previously mentioned technique to get | cos  |, but really need to measure BF’s D S ( * )+ D S ( * )-, J/  , J/  etc (angular analysis for VV states to get CP even fraction). Can use previously mentioned technique to get | cos  |, but really need to measure BF’s D S ( * )+ D S ( * )-, J/  , J/  etc (angular analysis for VV states to get CP even fraction). In the presence of NP  SM   SM +  NP   NP In the presence of NP  SM   SM +  NP   NP Measurements of  CP Measurements of  CP  D0: 0.17±0.09±0.03 & CDF: (statistically limited)  D0: 0.17±0.09±0.03 & CDF: (statistically limited)  CP :  (B s  K + K - )=1.53±0.18±0.02 ps (CDF)  CP :  (B s  K + K - )=1.53±0.18±0.02 ps (CDF)  CP : B(Ds (*)+ Ds (*)- )=(7.1±3.5±2.7)%  CP : B(Ds (*)+ Ds (*)- )=(7.1±3.5±2.7)% These exclusive modes could be measured by a B-factory. See A. Drutskoy [hep-ph/ ] These exclusive modes could be measured by a B-factory. See A. Drutskoy [hep-ph/ ] If there is a new physics phase then  SM cos  ; the Ds* modes difficult at LHC b because of the  from the D S * decay  B factories at Y(5S) can measure it… If there is a new physics phase then  SM cos  ; the Ds* modes difficult at LHC b because of the  from the D S * decay  B factories at Y(5S) can measure it… FPCP’06, R. Van Kooten hep-ex/

9/28 What do we know about the Y(5S) ?

10/28 Previous Data Samples 1985: Scans of Y(5S) region: 1985: Scans of Y(5S) region: CLEO: 0.07 fb -1 (on peak) CLEO: 0.07 fb -1 (on peak) CUSB: 0.12 fb -1 (on peak) CUSB: 0.12 fb -1 (on peak) CLEO PRL , 1985 CUSB PRL 54, 377, 1985 CUSB fit to modified potential model Y(5S) Y(6S)? Evidence for B s production at Y(5S) inconclusive

11/28 Recent Data Collected at the Y(5S) 2003: CLEO collected 0.4 fb -1 on the Y(5S). Goals were: 2003: CLEO collected 0.4 fb -1 on the Y(5S). Goals were: Understand the composition of the Y(5S) Understand the composition of the Y(5S) Assess the physics potential of a B-factory operating at the Y(5S) Assess the physics potential of a B-factory operating at the Y(5S) Measurements of B s decays. Measurements of B s decays. 2005: Belle collected about 1.86 fb -1 on Y(5S) 2005: Belle collected about 1.86 fb -1 on Y(5S) 2006: Belle collected about 22 fb -1 on Y(5S) (being processed) 2006: Belle collected about 22 fb -1 on Y(5S) (being processed)

12/28 Cross-Section Measurements Count hadronic events Count hadronic events Subtract continuum from below-Y(4S) Subtract continuum from below-Y(4S) Scale by ratios of luminosity, s=E cm 2 Scale by ratios of luminosity, s=E cm 2 Luminosity ratio significant source of systematic error, since  (5S)~0.1  (continuum), and 300 MeV below Y(5S) Luminosity ratio significant source of systematic error, since  (5S)~0.1  (continuum), and 300 MeV below Y(5S) Cross-check L ratio using high momentum tracks (0.6<p/p max <0.8) Cross-check L ratio using high momentum tracks (0.6<p/p max <0.8) Results: Results: CLEO:  (5S)=(0.301±0.002±0.039) nb CLEO:  (5S)=(0.301±0.002±0.039) nb BELLE:  (5S)=(0.305±0.002±0.0016) nb BELLE:  (5S)=(0.305±0.002±0.0016) nb Remarkable agreement,  R~0.4 Remarkable agreement,  R~0.4 PRL95, (1995) hep-ex/

13/28 Separating Final States MC Many final states accessible at 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 separated from the 2-body, but not well separated from each other.  Only for BB and B s B s does M bc = M(B), M(B s ), respectively.  Biases from neglect of 50 MeV  : B*B* : M bc (B) = M(B*)+1.7 MeV B s *B s *: M bc (B s ) = M(B s *)+0.1 MeV

14/28 Ordinary B Y(5S) Phys. Rev. Lett.96:152001,2006 Reconstruct B mesons in 25 decay modes  B  D (*)  D (*)   D 0  K , K  0, K   D +  K     J  K +, J  K *0, J  K S Invariant mass (GeV)  BBX  =(0.177±0.030±0.016) nb,  (5S)=(0.301±0.002±0.039) nb

15/28 B Cross-Sections & B S * Mass Production largest for B*B*, consistent with models: Production largest for B*B*, consistent with models:  (B*B*)/  (BBX) = (74±15±8)%  (B*B*)/  (BBX) = (74±15±8)%  (BB*)/  (B*B*) = (24±9±3)%  (BB*)/  (B*B*) = (24±9±3)%  (BB)/  (B*B*) < 90% cl  (BB)/  (B*B*) < 90% cl B S * mass B S * mass Compute  M bc = M bc (Bs*)-M bc (B*) Compute  M bc = M bc (Bs*)-M bc (B*) Largest systematic, beam energy scale cancels Largest systematic, beam energy scale cancels  M =  M bc MeV (kinematic bias)  M =  M bc MeV (kinematic bias) Obtain Obtain M(B S *)-M(B*)=(87.6±1.6±0.2) MeV M(B S *)-M(B*)=(87.6±1.6±0.2) MeV Use precise B* mass to get M(B s *) Use precise B* mass to get M(B s *) M(B s *)=( ± 1.6 ± 0.6) MeV M(B s *)=( ± 1.6 ± 0.6) MeV M(B S *)-M(B S )=(45.7±1.7±0.7) MeV M(B S *)-M(B S )=(45.7±1.7±0.7) MeV Consistent, as expected from Heavy Quark Symmetry with M(B*)-M(B) =45.78±0.35 MeV Consistent, as expected from Heavy Quark Symmetry with M(B*)-M(B) =45.78±0.35 MeV B*B* BB* BB BB ( * )  BB  CLEO Project data onto M bc axis Fit for BB, BB*, and B*B* yields and for each. B*B* peak gives the beam energy calibration ! 6.4±1.3 MeV from expected!

16/28 Exclusive B s Analyses (CLEO) Phys. Rev. Lett.96:022002, cand. 10 cand.

17/28 Exclusive B s Analyses (Belle) 7 events in B s * B s * 3 events in B s * B s * B s  D s ( * )+  - B s  J/  D s +   +, D s +  K* 0 K +, D s +  K s K + 9 events in B s * B s * 4 events in B s * B s * B s  D s +   B s  D s *+     

18/28 Fits for B s B s, B s B s *, B s *B s * (Belle) Potential models predict B s * B s * dominance over B s *B s and B s B s channels, but not so strong < M BC <5.429 GeV/c 2 B s * N ev =20.0 ±  5.384< M BC <5.405GeV/c 2 B s * B s B s 5.36< M BC <5.38GeV/c 2 Take slices in M bc  Project on  E (all modes combined)

19/28 Inclusive B s Analyses Use inclusive particle yield Use inclusive particle yield Choose a particle that has very different decay rates from B & B S Choose a particle that has very different decay rates from B & B S Ex: D S Ex: D S measure Model estimate based on quark level diagrams and measured ordinary B decay rates  B(B S →D S X) =(92±11)% Solve for f s

20/28 f s from D s Yields (CLEO) Y(5S) Y(4S) Y(5S) continuum x ( |p|/E beam ) Branching Fraction D s   B (B S → D S X) =(92±11)%

21/28 f s from D s Yields (Belle) Y(5S) D s   ± 100 ev points:5S hist: cont After continuum subtraction and efficiency correction: B (Y(5S) -> D s X) / 2 = (23.6 ± 1.2 ± 3.6) % f s = (17.9 ± 1.4 ± 4.1 )% N bb and BF(D s   ) dominant uncertainties B (D s   + ) = (4.4 ± 0.6)% from PDG 2006 Drutskoy, et al hep-ex/

22/28 f s from D 0 Yields (Belle) PDG 2006: B(B s  D 0  X) = (8 ± 7) % Spectator model, ala hep- ex/ CLEO B(B -> D 0  X) = (64.0 ± 3.0) % B(D 0  K -  + ) = (3.80 ± 0.07) % After continuum subtraction and efficiency correction: Bf (Y(5S)  D 0 X) / 2 = (53.8 ± 2.0 ± 3.4) % f s = (18.1 ± 3.6 ± 7.5 )% Y(5S) (55009 ± 510) ev D 0 -> K -  + points:5S hist: cont Combining with D s result: f s = (18.0 ± 1.3 ± 3.2 )% N bb dominant uncertaintiy

23/28 Measurement of f S Using  Yields Here we need B(B S →  X) Use CLEO-c inclusive yield measurements: B(D o →  X)=(1.0±0.10±0.10)% B(D + →  X)=(1.0±0.10±0.20)% B(D S →  X)=(16.1±1.2±1.1)% (Preliminary [hep-ph/ ], D s   X updated) From B(B →  X) = (3.5±0.3)%  find most of  ’s arise from B→D→  & B→D S →  Predict that B(B S →  X) = (16.1 ± 2.4)% known

24/28 Results on f S Using  Yields Reconstruct   K + K - Reconstruct   K + K - CLEO inclusive  yields, for x<0.5, R 2 <0.25 CLEO inclusive  yields, for x<0.5, R 2 <0.25 On Y(4S) On Y(5S) Cont’m Y(5S) Y(4S), scaled Continuum-subtracted spectra

25/28 Summary of f S Measurements Plot shows statistical (dark line) & systematic errors added linearly Plot shows statistical (dark line) & systematic errors added linearly Recall, model dependencies Recall, model dependencies A model-independent approach, exploiting the large difference in mixing between B and B s and measuring like-sign and opposite sign leptons. (Sia & Stone, hep-ph/ ) A model-independent approach, exploiting the large difference in mixing between B and B s and measuring like-sign and opposite sign leptons. (Sia & Stone, hep-ph/ ) Could also do a double-tagged analysis, ala Mark III, CLEO-c. Could also do a double-tagged analysis, ala Mark III, CLEO-c. (Both require large samples) (Both require large samples)

26/28 Rare Exclusive B s decays (Belle)   K+K-K+K- D S ( * )+ D S ( * )- Access to 

27/28 Expected Yields at Y(5S) ~100K B s produced per fb -1 at Y(5S). ModeApproximate Reconstructed Yield on 5S (50 fb -1 ) LHCb Expected Reconstructed Yield (2 fb -1 ) Notes BsDsBsDsBsDsBsDs25080,000 B s  J/  60100,000 B s  D s  D s  B s  D s  D s (*)  B s  D s (*)  D s (*)  ,000?? BsK+K-BsK+K-BsK+K-BsK+K-5037,000 B s   2-4? BF = (assumed) B s   109,000 BF = 21x10 -6 (assumed) O(10%) model-independent B s BF’s would probably require several ab -1 at Y(5S) (my back of the envelope)

28/28 Summary More recent investigations of Y(5S): More recent investigations of Y(5S): About 1/3 of Y(5S) produces B s pairs, mostly B s *B s *. About 1/3 of Y(5S) produces B s pairs, mostly B s *B s *. Ordinary B production dominated by B*B* (~2/3 of all B production) Ordinary B production dominated by B*B* (~2/3 of all B production) Both consistent with coupled-channel model predictions, although Bs*Bs* rate appears higher than predictions (20 fb -1 sample from Belle should resolve this). Both consistent with coupled-channel model predictions, although Bs*Bs* rate appears higher than predictions (20 fb -1 sample from Belle should resolve this). Precise B s * mass obtained from CLEO. Precise B s * mass obtained from CLEO. Large mixing frequency makes time-dependent CPV measurements inaccessible at Y(5S). This is where LHC b excels. Large mixing frequency makes time-dependent CPV measurements inaccessible at Y(5S). This is where LHC b excels. Y(5S) data can provide some complementary information on  to the time-dependent and time-integrated measurements at LHC b. Y(5S) data can provide some complementary information on  to the time-dependent and time-integrated measurements at LHC b. Results from ~20 fb -1 Y(5S) sample from Belle should be available early in 2007, stay tuned… Results from ~20 fb -1 Y(5S) sample from Belle should be available early in 2007, stay tuned…

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