Angular Analysis of Bs->J/ψϕ Decays and Measurement of ΔΓ and ϕs
This webpage summarizes the blessed results for the measurement of the lifetime difference and CP violating phase in the Bs system in the fully reconstructed decay Bs->J/ψϕ. We obtain a signal yield of 2506 +/- 51 events.
The same angular analysis method exploit for this measurement was also used to analyse B0->J/ψK* decays.
A more detailed summary of the results can be found in this public note.
Fixing ϕs=0 in Bs->J/ψϕ:
We measure a lifetime difference for the heavy and light Bs meson of:
ΔΓ = 0.076 -0.063+0.059 (stat) +/- 0.006 (syst) ps-1
The resulting mean lifetime measurement for the Bs is:
cτs = 456 +/- 13 (stat) +/- 7 (syst) μm
The correlation between ΔΓ and cτs is 60%.
For the amplitudes we obtain:
|A0|2 = 0.530 +/- 0.021 (stat) +/- 0.007 (syst)
|A|||2 = 0.230 +/- 0.027 (stat) +/- 0.009 (syst)
Below are all figures meant for download in several file formats.
- Figure 1 (eps),
(png),
(gif),
(jpg): Invariant mass distribution after loose precut selection.
- Figure 2 (eps),
(png),
(gif),
(jpg): Invariant mass distribution after the network selection.
- Figure 3 (eps),
(png),
(gif),
(jpg): Lifetime distribution (using lenght).
- Figure 3a (eps),
(png),
(gif),
(jpg): Lifetime distribution (using time).
- Figure 4 (eps),
(png),
(gif),
(jpg): cos(Θ) angular distribution.
- Figure 5 (eps),
(png),
(gif),
(jpg): cos(Ψ) angular distribution.
- Figure 6 (eps)
(png),
(gif),
(jpg): ϕ angular distribution.
- Figure 17 (eps)
(png),
(gif),
(jpg): Angular distributions, all in single plot.
- Figure 7 (eps),
(png),
(gif),
(jpg): The distribution of the Neural Network output for background(data) and signal(MC simulation).
- Figure 8 (eps),
(png),
(gif),
(jpg): The purity versus the Neural Network output for the trainings sample.
- Figure 9 (eps),
(png),
(gif),
(jpg): Significance of the signal for different cuts on the Neural Network output.
- Figure 10 (eps),
(png),
(gif),
(jpg): Data/MC comparison of the network output.
- Figure 11 (eps),
(png),
(gif),
(jpg): The likelihood scan for ΔΓ
- Figure 12 (eps) ,
(png),
(gif),
(jpg): The likelihood scan for cτs
- Figure 13 (eps),
(png),
(gif),
(jpg): The likelihood scan for the strong phase.
Letting ϕs float in Bs->J/ψϕ:
In this case we do not present a point estimate, since the fit result is biased for the given statistics. Therefore we created a confidence region, which shows all compatible values for our measured values of ϕs and ΔΓ on data.
Below are all figures meant for download in several file formats.
General Plots
