Measurement of $B_c^+$ production in proton-proton collisions at   $\sqrt{s}=8$ TeV
  Production of $B_c^+$ mesons in proton-proton collisions at a center-of-mass energy of 8 TeV is studied with data corresponding to an integrated luminosity of $2.0~{\rm fb}^{-1}$ recorded by the LHCb experiment. The ratio of production cross-sections times branching fractions between the $B_c^+\to J/\psi \pi^+$ and $B^+\to J/\psi K^+$ decays is measured as a function of transverse momentum and rapidity in the regions $0 < p_{\rm T} < 20~{\rm GeV}/c$ and $2.0 < y < 4.5$. The ratio in this kinematic range is measured to be $(0.683\pm0.018\pm0.009)\%$, where the first uncertainty is statistical and the second systematic. 
LHCb collaboration: R. Aaij, B. Adeva, M. Adinolfi, A. Affolder, Z.   Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexan...
hep-ex