Determination of the sign of the decay width difference in the Bs0 system
LHCb Collaboration (Including: Back, J. J., Dossett, D., Gershon, T. J., Harrison, P. F., Kreps, Michal, Latham, Thomas, Pilar, T., Poluektov, Anton, Reid, Matthew M., Silva Coutinho, R., Whitehead, M. (Mark) and Williams, M. P.). (2012) Determination of the sign of the decay width difference in the Bs0 system. Physical Review Letters, Vol.108 (No.24). Article Number 241801. ISSN 0031-9007
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Official URL: http://dx.doi.org/10.1103/PhysRevLett.108.241801
The interference between the K+K- S-wave and P-wave amplitudes in Bs0→J/ψK+K- decays with the K+K- pairs in the region around the ϕ(1020) resonance is used to determine the variation of the difference of the strong phase between these amplitudes as a function of K+K- invariant mass. Combined with the results from our CP asymmetry measurement in Bs0→J/ψϕ decays, we conclude that the Bs0 mass eigenstate that is almost CP=+1 is lighter and decays faster than the mass eigenstate that is almost CP=-1. This determines the sign of the decay width difference ΔΓs≡ΓL-ΓH to be positive. Our result also resolves the ambiguity in the past measurements of the CP violating phase ϕs to be close to zero rather than π. These conclusions are in agreement with the standard model expectations.
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