An Updated Measurement of the CP Violating Phase β_{s}^{J/ψ φ} with L=5.2 fb^{1}
Primary Authors: F. Azfar, J. Boudreau, N. Bousson, M. Feindt, J.P. Fernandez, K. Gibson, G.Giurgiu, G. Gomez
Ceballos, T. Kuhr, M. Kreps, L. Oakes, J. Morlock, M. Paulini, E. Pueschel, A.Schmidt
Introduction
This webpage summarizes the CDF preliminary result updating the flavortagged determination of
CP violation in B_{s} → J/ψ φ decays corresponding
to 5.2 fb^{1} data. In addition to doubling the previous sample size, several improvements have been made to the analysis. These include fully incorporating potential contamination of
the B_{s} → J/ψ φ signal by B_{s} → J/ψ KK or B_{s} → J/ψ f_{0}(980) (where the nonresonant KK and f_{0}(980) are Swave
states) into the likelihood fit, improvements to the NN selection and optimization, and full calibration of particle ID and flavour tagging. This analysis uses the updated and recalibrated
Same Side Kaon Tagger.
This result is described in this
public note
This result was first presented at FPCP2010, the slides are
here
The slides from the Fermilab Wine and Cheese talk for this update are here
See also the previous results at
First FlavorTagged Determination of Bounds on CP Violation in B_{s} → J/ψ φ Decays
with L = 1.3 fb^{1} published in PRL 100, 161802 (2008)
and
Updated measurement of CP violating phase β_{s}^{J/ψ φ} with 2.8 fb^{1}
Results
We present 68% and 95% confidence regions
in the β_{s}ΔΓ plane:
Assuming the standard model predictions of β _{s} and ΔΓ, the
probability of a deviation as large as the level of the observed data
is 44%, corresponding to 0.8 σ .
Additionally we present a confidence interval in β _{s}, where ΔΓ is treated as a nuisance
parameter, and find that β_{s} is within [0.02,0.52] U [1.08,1.55] at the 68% CL and within [π/2, 1.44] U [0.13, 0.68] U [0.89, π/2] at the 95% CL.
Assuming no CP violation (β _{s}^{J/ψ φ} = 0), we
also measure the mean lifetime,the decay width difference, the transversity amplitudes and the strong phase φ _{⊥} :
cτ_{s} = 458.6 ± 7.6 (stat) ± 3.6 (syst) μm
ΔΓ_{s} = 0.075 ± 0.035 (stat) ± 0.01 (syst) ps^{1}
A_{}(0)^{2} = 0.231 ± 0.014 (stat) ± 0.015 (syst)
A_{0}(0)^{2} = 0.524 ± 0.013 (stat) ± 0.015 (syst).
φ_{⊥} = 2.95 ± 0.64 (stat) ± 0.07 (syst)
These results give the world's most precise single measurement of the B _{s} lifetime and decay width difference. We find the Swave contamination of the signal φ meson to be < 6.7%
at the 95% CL
The likelihood
We provide the information for use of the CDF 35dimensional likelihood in global fits and combinations in two formats. One is a statistics consisting in coveragecorrected
profilelikelihood ratios as a function of β_{s} and ΔΓ in which the likelihood has been profiled over the other 33 parameters. The other is
the full multidimensional likelihood function, as a function implemented on a server, and its representation as a Markov chain in a root file. Instructions on how to use
this information are here
Figures
Below are all figures meant for download.
Likelihood contours
 (eps),
(gif): 2D β_{s}  ΔΓ likelihood profile with full coverage adjustment
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(gif): 1D β_{s} likelihood profile with full coverage adjustment
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(gif): 2D β_{s}  ΔΓ likelihood profile with nonGaussian error adjustment only (no systematics)
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(gif): 1D β_{s} likelihood profile with nonGaussian error adjustment only (no systematics)
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(gif): 2D β_{s}  ΔΓ likelihood profile with no coverage adjustment
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(gif): 1D β_{s} likelihood profile with no coverage adjustment
Coverage adjustment
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(gif): Distribution of 1CL for coverage adjustment of tagged 2D likelihood profile
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(gif): Distribution of 1CL for coverage adjustment of tagged 1D likelihood profile
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(gif): Distribution of 1CL for coverage adjustment of untagged 2D likelihood profile
Selection, yield, angular efficiencies
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(gif): B_{s} yield
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(gif): B_{s} mass distribution with ct>60μm
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(gif): KK invariant mass distribution
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(gif): KK invariant mass distribution with ct>60μm
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(gif): B_{s} NN training
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(gif): NN signal efficiency
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(gif): NN signal purity
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(gif): NN output
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(gif): NN sensitivity, toy MC with β_{s}=0.0
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(gif): NN sensitivity, toy MC with β_{s}=0.3
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(gif): NN sensitivity, toy MC with β_{s}=0.5
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(gif): NN significance curve
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(gif): Angular efficiencies in reweighted realistic MC
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(gif): Starting background angular functions
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(gif): Starting background angular functions overlaid with angular efficiencies
Flavor tagging (see also SSKT)
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(gif): B^{+} yield (for OST calibration)
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(gif): OST measured vs. predicted dilution for B^{+} decays
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(gif): OST measured vs. predicted dilution for B^{} decays
Swave studies
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(gif): Swave KK fraction of signal
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(gif): 2D β_{s}  ΔΓ likelihood profile comparison between fit including and without Swave KK component (no coverage
adjustment)
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(gif): B_{s} mass fit with wide KK invariant mass window, to get fractions of signal, combinatorial bkg and B^{0} reflections for KK mass study
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(gif): KK invariant mass with projections of signal φ, combinatorial bkg and B^{0} reflection fractions
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(gif): KK invariant mass with projections of signal φ, combinatorial bkg and B^{0} reflection fractions and Swave f_{0} component
fixed to central value from full likelihood fit
Fit cross checks
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(gif): untagged fit: 2D β_{s}  ΔΓ likelihood profile with full coverage adjustment
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(gif): overlay of fully adjusted 2D β_{s}  ΔΓ likelihood profile for tagged and untagged fits
 (eps),
(gif): untagged fit: 2D β_{s}  ΔΓ likelihood profile with full coverage adjustment
 (eps),
(gif): untagged fit: 2D β_{s}  ΔΓ likelihood profile with non Gaussian adjustment (no systematics)
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(gif): untagged fit: 2D β_{s}  ΔΓ likelihood profile with no adjustment
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(gif): untagged fit: 1D β_{s}  ΔΓ likelihood profile with no adjustment
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(gif):tagged fit: 2D β_{s}  ΔΓ likelihood profile for L=01.35fb^{1}
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(gif):tagged fit: 2D β_{s}  ΔΓ likelihood profile for L=1.352.8fb^{1}
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(gif):tagged fit: 2D β_{s}  ΔΓ likelihood profile for L=2.85.2fb^{1}
Fit projections
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(gif): Bs lifetime projection in signal region
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(gif): Bs lifetime projection in sideband region
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(gif): Bs lifetime error projection in signal region
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(gif): Bs lifetime error projection in sideband region
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(gif): Bs signal angular projection
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(gif): Bs background angular projection
