Determination of the X(3872) Meson Quantum Numbers

The quantum numbers of the X(3872) meson are determined to be J^PC=1⁺⁺ based on angular correlations in B⁺→X(3872)K⁺ decays, where X(3872)→π⁺π^-J/ψ and J/ψ→μ⁺μ^-. The data correspond to 1.0fb^-1 of pp collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements J^PC=2^-+ is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X(3872) state.