Search for a Structure in the Bs0π± Invariant Mass Spectrum with the ATLAS Experiment

A search for the narrow structure, X (5568 ), reported by the D0 Collaboration in the decay sequence X →B_s⁰π^±, B_s⁰→J /ψ ϕ , is presented. The analysis is based on a data sample recorded with the ATLAS detector at the LHC corresponding to 4.9 fb^-1 of p p collisions at 7 TeV and 19.5 fb^-1 at 8 TeV. No significant signal was found. Upper limits on the number of signal events, with properties corresponding to those reported by D0, and on the X production rate relative to B_s⁰ mesons, ρ_X, were determined at 95% confidence level. The results are N (X )<382 and ρ_X<0.015 for B_s⁰ mesons with transverse momenta above 10 GeV, and N (X )<356 and ρ_X<0.016 for transverse momenta above 15 GeV. Limits are also set for potential B_s⁰π^± resonances in the mass range 5550 to 5700 MeV.