Search for beautiful tetraquarks in the ?(1S)(+-) invariant-mass spectrum

The (1 S) invariant-mass distribution is investigated for a possible exotic meson state composed of two b quarks and two b quarks, X bbbb. 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 13TeV, corresponding to an integrated luminosity of 6.3 fb. No signi fi cant 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 bbbb state. The limits are set in the fi ducial volume where all muons have pseudorapidity in the range [2 : 0; 5 : 0], and the X bbbb state has rapidity in the range [2 : 0; 4 : 5] and transverse momentum less than 15 GeV/c.