Angular Analysis of Bs->J/ψϕ Decays and Measurement of ΔΓ and ϕs
Primary authors: Gian Piero Di Giovanni, Michael Feindt, Ivan Furic,
Khaldoun Makhoul, Michal Kreps, Thomas Kuhr, Michael Milnik, Christoph
Paus, Aurore Savoy-Navarro
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
