Tristan du Pree

1
Having a lookin the box

• Tristan du Pree
• LHCb, Nikhef
• Joint school, Spa

2
B physics

• VCKMVCKM1
• Overconstrain CKM-matrix
• CP violation
• Precision measurements

3
CKM-matrix
Three generations 4 components (3 real, 1 phase)
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Vts
Higher order Phase 0.03
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CPV in the interference of mixing and decay

• Final state f is a CP-eigenstate

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fs

• ACP sin(fsfNP)sin?mst

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Oscillation CP-asymmetry

• Amplitude
• fs
• Resolution
• Mistag

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Channel Bs ? J/? f

• 100K events per year

sinfs resolution mistag
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CP-even vs CP-odd

• Final state mixture CP-eigenstates
• CP-even and CP-odd different sign

• Solution
• Different polarizations different angular
  distributions
• Angular analysis

ACP Aevensinfssin?mst -Aoddsinfssin?mst
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Angular acceptance

• Wrong fraction ? wrong fs

Not a parabola!
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Acceptance weights

• Dont parametrize
• Solve likelihood maximization
• Acceptance weight functions from full MC

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It works!

• If full MC good
• avoid 20 systematic error

In Aodd 0.16
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Conclusions

• CKM-matrix gives flavour couplings
• By overconstraining one is sensitive to new
  processes
• To measure Vts one has to perform an angular
  analysis
• We can deal with angular acceptances

DO IT!
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BACKUP
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Detector
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NP
17

• Triangle, bij

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CPV (in interferentie)

• Simpel voorbeeld (Max thesis)

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B0B0 mixing ARGUS, 1987
Observe a fully reconstructed, mixed, event, with
no possible background. In addition, they
measure the like sign lepton fraction, and find
that 17 of B0 and B0 mesons mix before they
decay ? tB1.5 ps, Dm0.5/ps
First hint of a really large mtop!
Phys.Lett.B192245,1987
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Back to decays to CP eigenstates
t
Amplitude
t0
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Mixing Diagrams Dmd
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Measuring B mixing
where
If mt would be order of 10 GeV/c2, B mesons would
decay long before they have the change to
oscillate
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Back to decays to CP eigenstates
Amplitude
t0
t
CP