This page outlines the measurement of the
Bs0 mixing phase βsJ/ψφ
in flavor-tagged
Bs0 → J/ψφ decays,
using the full Run II data set collected by the CDF experiment
at the Fermilab's Tevatron collider corresponding to an integrated
luminosity of about 9.6 fb-1.
Further information can be found in arxiv:1208.2967.
We analyze approximately 11000
Bs0 → J/ψφ decays collected by a low-pt dimuon trigger,
thus almost doubling the statistics of
the previous iteration of the analysis (Phys. Rev. D 85, 072002 (2012)),
and report confidence regions in one- and two-dimensional βsJ/ψφ and
(βsJ/ψφ, ΔΓs) spaces.
The analysis technique and the employed tools reflect closely those reported in the previous analysis.
The opposite-side flavor tagging algorithms have been entirely recalibrated using about 82000 B± → J/ψK±
decays collected in the whole Run II sample, achieving a tagging performance of εD2= (1.39 ± 0.01)%.
The same-side-kaon tagging algorithms have only been used in half of the data sample (εD2= (3.2 ± 1.4)%),
since calibration on the full sample has not been completed yet.
This degrades the statistical resolution of the mixing phase measurement by no more than 15%.
From the one-dimensional profile likelihood in βsJ/ψφ, including systematic uncertainties, we find βsJ/ψφ ∈ [-π/2, -1.51] ∪ [-0.06, 0.30] ∪ [1.26, π/2] at the 68% confidence level, and βsJ/ψφ ∈ [-π/2, -1.36] ∪ [-0.21, 0.53] ∪ [1.04, π/2] at the 95% confidence level, in agreement with the value suggested by the CKM hierarchy.
We present 68% and 95% confidence regions in the βsJ/ψφ-ΔΓs plane including systematic uncertainties:
Assuming no CP violation (βsJ/ψφ fixed at SM value), we also measure the mean lifetime, the decay width difference, the transversity amplitudes and the strong phase δ⊥ :
τs = 1.528 ± 0.019(stat) ± 0.009(syst) ps,
ΔΓs = 0.068 ± 0.026(stat) ± 0.009(syst) ps-1,
|A0(0)|2 = 0.512 ± 0.012(stat) ± 0.018(syst),
|A||(0)|2 = 0.229 ± 0.010(stat) ± 0.014(syst),
δ⊥ = 2.79 ± 0.53(stat) ± 0.15(syst) rad.
From these results we derive also the ratio ΔΓs/Γs=0.1039 ± 0.048(stat) ± 0.018(syst) and, using the world average B0 lifetime, τ(B0s)/τ(B0) = 1.006 ± 0.015(stat+syst), in agreement with theoretical expectations.
The fraction of S-wave in the K+K- mass range 1.009-1.028 GeV/c2 is determined from the angular information to be consistent with zero with O(2%) uncertainty, which is in agreement with our previous determination and the LHCb and ATLAS results, and inconsistent with the D0 determination. An auxiliary simultaneous fit of the K+K- and J/ψK+K- mass distributions, which includes the full resonance structure of the B0 → J/ψKπ, determines a (0.8 ± 0.2(stat))% K+K- S-wave contribution, in agreement with the central fit. The contamination from mis-identified B0 decays is (8.0 ± 0.2(stat))%, which is significantly larger than the 1-2% values derived assuming only P-wave B0 decays. If neglected, this additional B0 component could mimic a larger K+K- S-wave than present.
Below are all figures meant for download and CDF Likelihood in Root format to be used in combinations with other experimental results.
- (eps), (gif): 2D βsJ/ψφ-ΔΓ likelihood profile with full coverage adjustment
- (eps), (gif): 1D βsJ/ψφ likelihood profile with full coverage adjustment
- (eps), (gif): 2D βsJ/ψφ-ΔΓ likelihood profile with non-Gaussian error adjustment only (no systematics)
- (eps), (gif): 1D βsJ/ψφ likelihood profile with non-Gaussian error adjustment only (no systematics)
- (eps), (gif): 2D βsJ/ψφ-ΔΓ likelihood profile with no coverage adjustment
- (eps),
(gif): 1D βsJ/ψφ likelihood profile with no coverage adjustment
Likelihood contours (with ϕsJ/ψφ) - (eps), (gif): 2D ϕsJ/ψφ-ΔΓ likelihood profile with full coverage adjustment
- (eps), (gif): 1D ϕsJ/ψφ likelihood profile with full coverage adjustment
- (eps), (gif): 2D ϕsJ/ψφ-ΔΓ likelihood profile with non-Gaussian error adjustment only (no systematics)
- (eps), (gif): 1D ϕsJ/ψφ likelihood profile with non-Gaussian error adjustment only (no systematics)
- (eps), (gif): 2D ϕsJ/ψφ-ΔΓ likelihood profile with no coverage adjustment
- (eps),
(gif): 1D ϕsJ/ψφ likelihood profile with no coverage adjustment
Likelihood contours for new data ONLY (4.4 fb-1) - (eps), (gif): 2D ϕsJ/ψφ-ΔΓ likelihood profile with no coverage adjustment
- (eps),
(gif): 2D βsJ/ψφ-ΔΓ likelihood profile with no coverage adjustment
Coverage adjustment - (eps), (gif): Distribution of 1-CL for coverage adjustment of tagged 1D likelihood profile
- (eps),
(gif): Distribution of 1-CL for coverage adjustment of tagged 2D likelihood profile
Yield - (eps), (gif): Bs yield
- (eps),
(gif): Bs mass distribution with ct>60μm
Auxiliary fit to determine K+K- S-wave and B0 → J/ψKπ components (ct(B)>60μm and K+K- mass in [0.98,1.2] GeV/c2) - (eps), (gif): J/ψK+K- mass distribution with fit projections overlaid
- (eps),
(gif): K+K- mass distribution with fit projections overlaid.
Flavor tagging (see also SSKT) - (eps), (gif): B+/- yield (for OST calibration)
- (eps), (gif): OST measured vs. predicted dilution for B+ decays
- (eps),
(gif): OST measured vs. predicted dilution for B- decays
Fit projections - (eps), (gif): Bs lifetime projection for all data
- (eps), (gif): Bs lifetime projection for signal (background subtracted data)
- (eps), (gif): Bs lifetime projection for background
- (eps), (gif): Transversity-angles projection for all data
- (eps), (gif): Transversity-angles projection for signal (background subtracted data)
- (eps),
(gif): Transversity-angles projection for background
Fit projections assuming SM mixing phase - (eps), (gif): Bs lifetime projection for all data
- (eps), (gif): Bs lifetime projection for signal (background subtracted data)
- (eps), (gif): Bs lifetime projection for background
- (eps), (gif): Transversity-angles projection for all data
- (eps), (gif): Transversity-angles projection for signal (background subtracted data)
- (eps),
(gif): Transversity-angles projection for background
Analysis data
-
We provide below the analysis data for use in combinations and phenomenological fits.
A root file contain the histogram of the bare profile-likelihood ratio (-2ΔLogL). As described in arxiv:1208.2967, the CDF likelihood ratio does not follow a chi-squared distribution and cannot be used for extracting confidence regions with nominal coverage. Another root file contains a statistics in which the value of a χ2-distributed profile-likelihood ratio is assigned to each point in the Δ Γ - ϕsJ/ψφ space, corresponding to the actual value of CL associated to that point. This statistics can be effectively used as "CDF-likelihood" with nominal coverage.
-
Each histogram has 32 bins in ϕsJ/ψφ over the interval [-3.2, 3.2]
and 48 bins in ΔΓ over the interval [-0.3, 0.3].
- (root): No Coverage Corrected Histogram,
need to set level 3.55 and 8.1 to obtain respectively the 68% and 95% CL regions.
- (root): Coverage Corrected Histogram.
Can set the nominal levels 2.3 and 5.99 to obtain respectively the 68% and 95% CL regions.
For sake of semplicity we also provide a root macro to draw the contours at the desired level. Detailed Instruction in the following README file.
- (macro.C): macro to draw contours.
- (README): User instructions.
- (gif): Example of contour in the space Δ Γ - ϕsJ/ψφ following the instructions written in the README file.
Likelihood contours (with βsJ/ψφ)
