Speaker
Judith Katzy
(DESY, HAMBURG)
Description
In this work, we present a measurement of the Bs0—>J/psi phi time–dependent CP asymmetry parameters using the combined Run-1 dataset. Bs0—>J/psi phi decay channel is sensitive to the new physics contributions, and already small deviations in a measurement of phi_s would be hints for the existence of the new particles.
A four-dimensional unbinned maximum likelihood fit, which also includes information of the Bs0 production flavour, is used to extract the parameters from the corresponding measured decay time and angular distributions of the Bs0 → J/ψ(μ+μ−)φ(K+K−) decay. Apart from CP-violating mixing phase phi_s, several parameters describing the Bs0 meson system are measured. These include the Bs0 lifetime 1/Γs, the decay width difference ∆Γs between the heavy and the light mass eigenstates, and the transversity amplitudes |A0(0)| and |A∥(0)|. The results are compatible with Standard Model predictions. Within the given uncertainties, the ATLAS results are consistent with the measurements from other LHC experiments. The significance of the deviation from the Standard Model prediction will be clarified once more data has been accumulated following the LHC upgrade and the statistical precision of the measurements improved.
Author
Judith Katzy
(DESY, HAMBURG)
