Gabriella Sciolla

1
Title
Searching for New Physics at the B factories
Measurements of sin2b at BaBar

• Gabriella Sciolla
• Massachusetts Institute of Technology
• Representing the BaBar Collaboration
• Beauty 2005 - Assisi, June 20-24, 2005

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BaBar and PEP-II

• BaBar detector
• 4p collider detector
• PEP-II asymmetric B factory
• 9.0 GeV e- beam
• 3.1 GeV e beam
• Peak luminosity
• 9.1 x 1033 cm-2s-1
• Integrated luminosity
• Delivered gt268 fb-1

e
e
Most results in this talk are based on 227 M BB
events
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The Beauty of the Unitarity Triangle

• Two ways of looking for New Physics
• Compare measurement of sides and angles
• Measure angles in channels with different
  sensitivity to New Physics

4
The three roads to b

• Charmonium modes
• J/? KS, ?(2S) KS, ?c1 KS, ?c KS
• J/? KL
• J/? K0 (K0 ? KS p0)
• Open-charm modes
• D D-, D D-, D D-
• Penguin-dominated modes
• f K0, K K- KS, KS KS KS
• ?' KS
• KS p0, ? KS, f0(980) KS

5
CP violation in interference between mixing and
decays

(hf)

• When only one diagram contributes to the final
  state
• Example B0? J/YKS

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How to measure the CP asymmetry

• .

e-
B0
e-
U(4S)
m
B0
p
p-
m-
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The golden mode for sin2b B0? charmonium K0
Phys. Rev. Lett. 94, 161803 (2005)

• Theoretically clean
• Experimentally clean
• Relatively large BF (10-4)

CP sample
mES GeV
DE MeV
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Phys. Rev. Lett. 94, 161803 (2005)
The golden mode for sin2b CP fit in B?
charmonium K0
Unbinned maximum likelihood fit to Dt distribution
CP1
CP-1
sin(2b) 0.722 0.040stat 0.023syst
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SM test in B0 ? charmonium K0
cos(2ß)lt0

• Compare sides and angles
• Both BaBar and Belle results used
• Ambiguity resolved measuring sign(cos2b) in
  B0?J/YK
• cos(2b)-0.68 excluded at 86.6CL PRD 71
  (2005)032005
• Excellent agreement with constraints from the
  sides
• Another SM triumph?
• .

cos(2ß)gt0
SM test 2 Compare b in various channels
Measurements of angles NOT included in fit
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The b?ccd trees B0 ? open charm
u,c,t

• Tree measures sin2b from b?ccd transitions
• Penguin expected to be small in SM (lt few )
• DD as large as Db 0.6 Grossman and Worah,
  1997

New Physics could have large effects
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The open charm trees Recent update B0
? DD-
New
BaBar Preliminary

• Vector-vector final state
• CP-even and CP-odd admixture
• Transversity analysis measures fCP-even

• CCP 0.06 0.17 0.03
• -SCP 0.75 0.25 0.03

fCP (87.5 ? 4.4 ? 0.7)
In good agreement with SM
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The open charm trees B0 ? D()? D?
hep-ex/0505092
DD- D-D DD-
Updated
Updated
New
-S 0.54 ? 0.35 ? 0.07 0.29 ? 0.33 ? 0.07 0.29 ? 0.63 ? 0.06
C 0.09 ? 0.25 ? 0.06 0.17 ? 0.24 ? 0.04 0.11 ? 0.35 ? 0.06
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The key to New Physics The Penguin Modes

• Decays dominated by gluonic penguin diagrams
• The typical example B0?fKS
• No tree level contributions
• In SM, top quark dominates the loop C0 Ssin2b
• Impact of New Physics could be significant
• New particles could participate in the loop ? new
  CPV phases
• Low branching fractions
• Measure ACP in as many b?sqq penguins as
  possible!
• f K0, K K- KS, ?' KS, KS p0, KS KS KS, ? KS,
  f0(980) KS

NP
SM
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The golden penguin B0 ? fK0
Phys. Rev. D 71, 091102(R) (2005)

• Combined fKS and fKL fit

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Related channel B0? KK-KS
Phys. Rev. D 71, 091102(R) (2005)

• For non resonant B0?KK-KS decays, hCP 2 feven-
  1
• feven measured from angular moment analysis of
  the KK- system

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A new golden penguin B0?KSKSKS
hep-ex/0502013 (accepted by PRL)

• Theoretically clean
• Penguin dominated CP1 eigenstate
• Experimentally challenging
• B decay vertex uses KS pseudo-particles and beam
  spot constraint

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The silver penguin B0 ? hKS
Phys. Rev. Lett. 94, 191802 (2005)

• Relative large BF 6 x 10-5
• Theoretically less clean than fKS
• Tree diagram possible
• but Cabibbo and color suppressed
• DS SYK-SPenguin 0.01QCDFact ? 0.1SU(3)

S?'Ks 0.30 0.14 0.02 C?'Ks -0.21 0.10
0.02
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The challenging penguins B0?p0KS, f0KS, wKS
hep-ex/0503011 hep-ex/0408095 hep-ex/0503018

• B0?p0KS
• dominated by
• tree contribution are non
  negligible (DS 0.1 0.2)
• Experimental challenge BCP decay vertex
  reconstruction (sDt1ps)
• B0?f0KS
• In SM dominated by
• B0?wKS
• In SM dominated by
• But tree can be relatively large

B0?p0KS B0?f0KS B0?wKS
-hf S 0.35 ? 0.04 0.95 ? 0.10 0.50 ? 0.02
C 0.06 ? 0.18 ? 0.03 -0.24 ? 0.31 ? 0.15 -0.56 ? 0.03
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sin2b in penguins BaBar only

• Although each
• measurement is
• compatible with J/YKS,
• a trend is visible
• hKS has the most
• significant shift
• (2.9 s if theory
• uncertainties neglected)
• but statistical errors are
• still large

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sin2b in penguins BaBar Belle
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Summary and Conclusion
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Backup slides ------------------------------------
--------------------------------
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Transversity analysis

• DD- is not a CP eigenstate
• sum of L0, 2 (CP even) and L1 (CP odd)
• CP odd fraction R? determined by transversity
  analysis

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DD analysis

• SM expectations
• DD-
• DD

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cos and sin fits in penguin modes
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The challenging penguins B0?p0 KS
hep-ex/0503011

• In SM these decays are dominated by
• tree contribution are non
  negligible
• DS 0.1 in model dependent QCD calculations
• DS 0.2 in SU(3)
• Experimentally challenging
• BCP decay vtx from KS and beam spot
• KS tracks with gt 3 SVT sDt1ps
• Unbinned max likelihood fit

Nsig 300 23
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Two more penguins B0? f0KS and B0? wKS
hep-ex/0408095 hep-ex/0503018

• B0? f0KS dominated by b? sss

B0 ? ?KS dominated by b ? sdd
Tree contamination can be relatively large
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The Other Trees Recent update B ?
DD-
Results presented at Moriond 2005
BaBar Preliminary

• Vector-vector final state
• CP-even and CP-odd admixture
• Transversity analysis measures fodd
• fodd (12.5 ? 4.4 ? 0.7)

• CCP 0.04 0.14 0.02
• -SCP 0.65 0.26 0.09-0.07 0.04

? Good agreement with SM
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Penguins vs tree