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:

s = 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.

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