Search for beautiful tetraquarks in the ϒ(1S)μ ⁺ μ ⁻ invariant-mass spectrum

The ϒ(1S)μ⁺μ⁻ invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two b¯ quarks, X_{b b¯ b b¯}. The analysis is based on a data sample of pp collisions recorded with the LHCb detector at centre-of-mass energies s=7, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb⁻¹. No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the X_{b b¯ b b¯} state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range [2.0, 5.0], and the X_{b b¯ b b¯} state has rapidity in the range [2.0, 4.5] and transverse momentum less than 15 GeV/c.[Figure not available: see fulltext.].