Abstract
A search for the rare decay Bs0 → µ+µ− has been performed with the ATLAS detector at the Large Hadron Collider LHC in proton-proton collisions at a centre of mass energy of √s = 7 TeV using 2.4 fb−1 of integrated luminosity. The observed number of signal events is consistent with the background expectations and the resulting upper limit on the branching fraction is set to ℬ(Bs0 → µ+µ−) < 2.2(1.9) × 10−8 at 95% (90%) confidence level. A time dependent measurement of CP-violation in the exclusive decay channel Bs0 → J/ψ(µ+µ−)ϕ(K+K−) has been performed with an integrated luminosity of 4.9 fb−1 at an energy of √s = 7 TeV. The resulting measurements of the CP-violation weak mixing phase ϕs = 0.22 ± 0.41 (stat.) ± 0.10 (syst.) rad and the decay width difference ΔΓs = 0.053 ± 0.021 (stat.) ± 0.008 (syst.) ps−1 are consistent with the theoretical predictions of the Standard Model and the world average values.
Highlights
Heavy flavour physics in the b-quark sector is sensitive to phenomena beyond the Standard Model (SM)
Non-SM contributions in the B0s − B0s mixing box diagram could alter this phase, which can be parametrised by φs = φSs M +φ∆s, where φSs M is the value predicted by SM and φ∆s describes additional phase contributions due to physics beyond the SM [3]
From 2.4 fb−1 of data collected in pp collisions at
Summary
Heavy flavour physics in the b-quark sector is sensitive to phenomena beyond the Standard Model (SM). Models beyond the SM can increase this branching ratio, any deviation from the SM predictions would indicate new physics. Non-SM contributions in the B0s − B0s mixing box diagram could alter this phase, which can be parametrised by φs = φSs M +φ∆s , where φSs M is the value predicted by SM and φ∆s describes additional phase contributions due to physics beyond the SM [3]. B0s → J/ψ(μ+μ−)φ(K+K−) decays for the measurement of φs and ∆Γs [5] by the ATLAS experiment at the LHC Both measurements use data collected by the ATLAS exp√eriment in pp collisions at a centre of mass energy of s = 7 TeV, corresponding to an integrated luminosity of ∼ 2.4 fb−1 (B0s → μ+μ−) and ∼ 4.9 fb−1 (B0s → J/ψφ).
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