Determination of the sign of the decay width difference in the bs0 system

The LHCb Collaboration

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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 (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/ψ 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 ΔΓ sΓ LH to be positive. Our result also resolves the ambiguity in the past measurements of the CP violating phase s to be close to zero rather than π. These conclusions are in agreement with the standard model expectations.

Original languageEnglish
Article number241801
Number of pages7
JournalPhysical Review Letters
Issue number24
Publication statusPublished - 11 Jun 2012
Externally publishedYes

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