Abstract
The CP-violating weak phase phi[s] of the Bs meson and the decay width difference Delta Gamma[s] of the Bs light and heavy mass eigenstates are measured with the CMS detector at the LHC using a data sample of Bs to J/Psi phi(1020) to mu+mu-K+K- decays. The analysed data set corresponds to an integrated luminosity of 19.7 inverse femtobarns collected in pp collisions at a centre-of-mass energy of 8 TeV. A total of 49,200 reconstructed Bs decays are used to extract the values of phi[s] and Delta Gamma[s] by performing a time-dependent and flavour-tagged angular analysis of the mu+mu-K+K- final state. The weak phase is measured to be phi[s] = -0.075 +/- 0.097 (stat) +/- 0.031 (syst) rad, and the decay width difference is Delta Gamma[s] = 0.095 +/- 0.013 (stat) +/- 0.007 (syst) inverse picoseconds.
Highlights
While no direct evidence of physics beyond the standard model (SM) has yet been found at the CERN LHC, the B0s meson provides a rich source of possibilities to probe its consistency
In this Letter, a measurement of the weak phase φs of the B0s meson and the decay width difference s between the light and heavy B0s mass eigenstates is presented, using the data collected by the CMS experiment in pp collisions at the LHC with a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb−1
The CP-violating weak phase φs originates from the interference between direct B0s meson decays into a CP eigenstate ccss and decays through B0s –B0s mixing to the same final state
Summary
While no direct evidence of physics beyond the standard model (SM) has yet been found at the CERN LHC, the B0s meson provides a rich source of possibilities to probe its consistency. The CP-violating weak phase φs originates from the interference between direct B0s meson decays into a CP eigenstate ccss and decays through B0s –B0s mixing to the same final state. Decay to the final state μ+μ− K+K− is analysed, and possible additional contributions to the result from the nonresonant decay B0s → J/ψ K+K− are taken into account by including a term for an additional amplitude (S-wave) in the fit. In this measurement the transversity basis is used [14]. Since direct CP violation is expected to be small theoretically [3] and is measured to be small [9], |λ| is set to 1.0
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