Search for a Structure in the B^⁰_sπ^±  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^⁰_sπ^±, B^⁰_s→J/ψφ, 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 pp 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^⁰_s mesons, ρ_X, were determined at 95% confidence level. The results are N(X)<382 and ρ_X<0.015 for B^⁰_s 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^⁰_sπ^± resonances in the mass range 5550 to 5700 MeV.