European Physical Journal C, cilt.74, sa.10, ss.1-13, 2014 (SCI-Expanded)
A study of meson production at LHCb is performed on proton–proton collision data, corresponding to 3.0 of integrated luminosity collected at centre-of-mass energies = 7 and 8. The fraction of Υ mesons originating from χ decays is measured as a function of the transverse momentum in the rapidity range. The radiative transition of the meson to Υ is observed for the first time. The χ mass is determined to be (Formula presented.) where the first uncertainty is statistical and the second is systematic.