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for the BaBar and Belle Collaborations

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1 for the BaBar and Belle Collaborations
Miami 2008 Topical Conference on Elementary Physics, Astrophysics, and Cosmology Fort Lauderdale, FL, Dec 16-21, 2008 BaBar B Factory Measurements of the b s(d)  “Radiative Penguin” Transition Rates Bruce A. Schumm Santa Cruz Institute for Particle Physics University of California, Santa Cruz for the BaBar and Belle Collaborations

2 Miami 2008: b  s(d) Transition Rates
Outline Effective Neutral Currents: General Motivation b  s Penguins SUSY parameter space implications b  s “Inclusive” approach B  XS “Semi-Inclusive” approach b  d Penguins and |Vtd/Vts| Motivation B → (ρ,ω)g “Exclusive” approach B → Xd “Semi-Inclusive” approach Status of |Vtd/Vts| Conclusions Bruce Schumm Miami 2008: b  s(d) Transition Rates

3 Effective Neutral Currents and Radiative Penguins
The SM b  s(d)  transition is high order (two weak plus one EM vertex) … Vtb Vt(s,d) so new physics can enter at leading order: + photon off any charged leg (d) (d) (d) Although rare (~ 5x10-4 for s and ~10-5 for d), the isolated high-energy photon is a powerful signature. Bruce Schumm Miami 2008: b  s(d) Transition Rates

4 Miami 2008: b  s(d) Transition Rates
Outline Effective Neutral Currents: General Motivation b  s SUSY parameter space implications Inclusive approach Other approaches b  d and |Vtd/Vts| Motivation B → (ρ,ω)g (“Standard” Approach) B → Xd (“Semi-Inclusive” Approach) Status of |Vtd/Vts| Conclusions Bruce Schumm Miami 2008: b  s(d) Transition Rates

5 B  s and SUSY Parameter Space
B  s constraints Direct searches (LEP) MSSM Constraints MA is CP-odd higgs bs has a significant impact on the tan-mA plane… Bruce Schumm Miami 2008: b  s(d) Transition Rates

6 B  s and SUSY Parameter Space (cont’d)
… on some of our favorite scenarios … Fate of “Snowmass” MSSM study points Bruce Schumm Miami 2008: b  s(d) Transition Rates

7 B  s and SUSY Parameter Space (cont’d)
… and just in general. C.F. Berger, J.S. Gainer, J.L. Hewett, T.G. Rizzo, “Supersymmetry Without Prejudice”, arXiv: v1 [hep-ph] Explore 107 points over 19-dimensional parameter space of CP-conserving MSSM b  s most effective constraint (72% of models surviving prior constraints are eliminated; better than direct searches for SUSY partners) Bruce Schumm Miami 2008: b  s(d) Transition Rates

8 The e+e- Cross Section in the Upsilon Region
The (4S) resonance is the lightest resonance that decays into “open Beauty” ( or ) Off-Peak Data (~10% of Sample) On-Peak Data (4S) resonance is ~1 nb at peak, competing with a “continuum” background of ~3 nb Bruce Schumm Miami 2008: b  s(d) Transition Rates

9 Miami 2008: b  s(d) Transition Rates
B Factory Data Sets 440 fb-1 700 fb-1 Bruce Schumm Miami 2008: b  s(d) Transition Rates

10 Inclusive Measurement of b  s: Introduction
Most exacting approach (“Inclusive”) is aggressive: Use only high-energy  as signature Suppress continuum with event shapes, requirement of a high-energy lepton. Estimate remaining contribution by scaling off-peak data. Challenge: background from 0()   decays (plus some fakes) in B decays qq + ττ BB XSγ Bruce Schumm Miami 2008: b  s(d) Transition Rates

11 Inclusive Measurement of b  s: Practicalities
To remove 0() background: Veto event if you find the 2nd photon (~45% efficient for 0() fakes) Estimate and subtract out cases for which 2nd photon is missed (S/B ~ 1/1) Requires knowledge of second photon efficiency to < 1%; measure using, e.g., 0s from e+e-  ;   +-0 Becoming limiting experimental uncertainty No s signal here; provides check of 0 subtraction BELLE: (3.370.43)x arXiv: fb-1 BaBar: (3.920.56)x PRL97, fb-1 NOTE: Measurements scaled to Ecms > 1.6 GeV Bruce Schumm Miami 2008: b  s(d) Transition Rates

12 b  s  Via a Sum of Exclusive Final States (BaBar)
Reconstruct a total of 38 exclusive b  s final states that comprise about 55% of the total width Fit to reconstructed mass of exclusive final state to determine signal yield This “Semi-Inclusive” approaches employs a fit to the mass distribution, for which backgrounds tend to be self-calibrating… Bruce Schumm Miami 2008: b  s(d) Transition Rates

13 BaBar Semi-Inclusive Analysis (continued)
But need to rely on models to correct for the 45% of states that are not measured (depends on mass M(Xs) that photon recoils against). RESULT BF(B  s) = (3.49  0.57)x10-4 PRD72:052004 82 fb-1 analyzed is less than 10% of world sample Has systematics independent of those of inclusive approach Mass Recoiling Against  Bruce Schumm Miami 2008: b  s(d) Transition Rates

14 Summary of Measurements of the b  s Rate
Experimental accuracy commensurate with theoretical control, but work continue on both ends A. Limosani, Melbourne Inclusive Semi-Inclusive Most of BaBar data set still unanalyzed Bruce Schumm Miami 2008: b  s(d) Transition Rates

15 Miami 2008: b  s(d) Transition Rates
Outline Effective Neutral Currents: General Motivation b  s SUSY parameter space implications Inclusive approach Other approaches b  d and |Vtd/Vts| Motivation B → (ρ,ω)g (“Standard” Approach) B → Xd (“Semi-Inclusive” Approach) Status of |Vtd/Vts| Conclusions Bruce Schumm Miami 2008: b  s(d) Transition Rates

16 Two independent diagrams provide sensitivity to CKM parameter Vtd
Measuring |Vtd/Vts| Two independent diagrams provide sensitivity to CKM parameter Vtd (d) B Mixing Vt(s,d) Note: In both cases, hadronic uncertainties minimized by comparing to corresponding Vts process (Bs mixing, b  s)  Observable is | Vtd / Vts | Radiative Penguins Bruce Schumm Miami 2008: b  s(d) Transition Rates

17 |Vtd/Vts| from Penguins: Motivation
ICHEP ’08 B Mixing Results [Farrington(CDF), Moulik(D0), averaged by DeLodovico(BaBar)]: How do penguins fit into the picture? SM effects suppressed by 10-5 relative to mixing Mixing: xd = mB/B ~ 1  mB ~ B Penguins: Br(bd) ~  d ~ 10-5 B Furthermore (Ali, Asatrian, Greub, Phys. Lett B 429, 87): “These [b  d] vertices are CKM-suppressed in the standard model, but new physics contributions may not follow the CKM pattern in flavor-changing-neutral-current transitions and hence new physics effects may become more easily discernible in B  Xd +  (and its charge conjugate) than in the corresponding CKM-allowed vertices b  s and b  sg” With |Vtd/Vts| precisely constrained by mixing, b  d is a compelling testbed for new physics. Bruce Schumm Miami 2008: b  s(d) Transition Rates

18 Exclusive Approach: B  () 
Standard (“Exclusive”) Approach: measure exclusive rate Br(B  () ); normalize with Br(B  K* ) (and ) Annihilation Diagram Values of 2 and R are state available from Ali, Parkhomenko, arXiv:hep-ph/ Ball, Zwicky, J. High. Energy Phys. 0604, 046 (2006); Ball, Jones, Zwicky, Phys. Rev. D (2007) at approximately 8% overall accuracy. Bruce Schumm Miami 2008: b  s(d) Transition Rates

19 Measurement of B(B  ()  )
Belle: New result this Spring 351 fb-1 (2006)  598 fb-1 (April 2008) BaBar: New result this Summer 316 fb-1 (April 2007)  423 fb-1 (July 2008) Challenge: BRs are small (<10-6); backgrounds are high continuum Neural Net with event shape, B tagging information, … B → K*; K* K Require excellent particle ID B → ( Veto if  found such that M ~ M(,) Bruce Schumm Miami 2008: b  s(d) Transition Rates

20 Measurement of B(B  () ) (continued)
Remaining separation achieved by two-dimensional fit to the largely independent kinematic variables “Energy-substituted mass”; since Ebeam ~ MB, largely a measurement of momentum balance EB = Ebeam for properly reconstructed candidate; total energy measurement *In e+e- CMS frame Example: BaBar B0  0  “self-calibrating” continuum background subtraction efficiencies (~5-15%) estimated with control samples Continuum Signal bs Feedthrough Bruce Schumm Miami 2008: b  s(d) Transition Rates

21 Recent Updates of B  () 
Phys.Rev.Lett.101:111801,2008, Erratum-ibid.101:129904,2008 BELLE:  598 fb-1 Mode Belle ’06 (x10-7) Belle ’08 (x10-7) +  0    BaBar:  423 fb-1 Phys.Rev.D78:112001,2008 Mode BaBar ’07 (x10-7) BaBar ’08 (x10-7) +  0    Bruce Schumm Miami 2008: b  s(d) Transition Rates

22 |Vtd/Vts| from Exclusive (,) Decays
Assuming static quark model, SU(3)F symmetry, can combine to get “isospin-averaged” BF, and then |Vtd/Vts|: BELLE: yielding Phys.Rev.Lett.101:111801,2008, Erratum-ibid.101:129904,2008 BaBar: yielding Phys.Rev.D78:112001,2008 assuming the world-average Combining, for exclusive radiative decay overall: Bruce Schumm Miami 2008: b  s(d) Transition Rates

23 Semi-Inclusive Approach: B  Xd  (Preliminary)
“New” Approach (BaBar): Reconstruct seven exclusive final states Xd in range 0.6 GeV/c2 < MXd < 1.8 GeV/c2 |Vtd/Vts|2 related to (bd)/(bs) with ~1% theoretical uncertainty [Ali, Asatrian, Greub, Phys. Lett. B 429, 87 (1998)] However, must correct for unmeasured regions: Higher-multiplicity final states Higher-mass hadronic component (i.e. MXd > 1.8 GeV/c2) Bruce Schumm Miami 2008: b  s(d) Transition Rates

24 Measured Regions for B  Xd(s) 
# 0 UNMEASURED XS MEASURED K* Region # bodies 0.5 < Mhad < 1.0 1.0 < Mhad < 1.8 1.8 < Mhad # bodies # 0 UNMEASURED Xd MEASURED Xd analysis only  and Xd analyses Mhad (MXd) Bruce Schumm Miami 2008: b  s(d) Transition Rates

25 B  X(s,d)  Partial Branching Fraction Results
Fit in high-mass Xd  region 1.0 < Mhad < 1.6 GeV/c2 Continuum background Xs, MisID background BABAR BABAR E MES Yields and partial branching fractions: High-mass b  Xd  PRELIMINARY Bruce Schumm Miami 2008: b  s(d) Transition Rates

26 Correction for Missing Modes
Try several models: MX given by “KN Model” Kagan & Neubert, Phys. Rev. D 58, (1998), with phase-space fragmentation As above, but with 50% replaced by mix of resonances Fix to measured b  s fragmentation Dominant systematic error for 1.0 < MX < 1.8 GeV/c2 Can improve with statistics (internal constraints) Errors: Stat.  Experimental Syst. arXiv:  [hep-ex]; submitted to PRL BABAR Primary experimental result PRELIMINARY Bruce Schumm Miami 2008: b  s(d) Transition Rates

27 Ratio of Total Widths and |Vtd/Vts|
Extrapolation to (bd)/(bs) Measured region 0.6 < MX < 1.8 is ~50% of width Extrapolate to full mass region via “KN Model”; KN calculation suggests negligible difference and uncertainty in extrapolation of the ratio (because ms,md << 1.8 GeV/c2?) BABAR BABAR PRELIMINARY Ali Asatrian Greub PRELIMINARY Expt. Theory arXiv:  [hep-ex]; submitted to PRL Bruce Schumm Miami 2008: b  s(d) Transition Rates

28 Global Status of |Vtd/Vts|
* PRELIMINARY * No evidence for non-Standard Model contribution to the decay width. Bruce Schumm Miami 2008: b  s(d) Transition Rates

29 Miami 2008: b  s(d) Transition Rates
Concluding Remarks B  s continues to be leading constraint on MSSM parameter space More data exists (~80% of BaBar sample) to improve measurement, but “inclusive” approach starting to be limited by difficult systematics “Semi-inclusive” approach has systematics independent of inclusive approach; very little of existing sample has been analyzed in this way. Radiative measurements of |Vtd/Vts| are becoming precise: | Vtd/Vts|rad =  0.020 Semi-inclusive approach works, and is independent of exclusive approach, with small theoretical uncertainty Agreement with SM (as constrained by B mixing) is good In principle, the severe SM suppression of this radiative process (x10-6 of B mixing) should make it very sensitive to new physics contributions. Have we fully thought through the meaning of this constraint? Bruce Schumm Miami 2008: b  s(d) Transition Rates

30 Miami 2008: b  s(d) Transition Rates
Backup Slides Bruce Schumm Miami 2008: b  s(d) Transition Rates

31 Isopsin-Averaged Branching Fractions
Assuming SU3(F) symmetry [B(B0) ~ B(B)] and (approximately true by static quark model) we can write from which it follows  Can combine +, 0,  results to derive |Vtd/Vts| from Bruce Schumm Miami 2008: b  s(d) Transition Rates

32 Miami 2008: b  s(d) Transition Rates
Bruce Schumm Miami 2008: b  s(d) Transition Rates

33 Miami 2008: b  s(d) Transition Rates
Bruce Schumm Miami 2008: b  s(d) Transition Rates

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