Observations of Orbitally Excited $B_{(s)}^{**}$ Mesons

Using 336~pb$^{-1}$ of 2011 data collected by the LHCb detector, we study the invariant mass distributions of $B^+ K^-$, $B^+ \pi^-$ and $B^0 \pi^+$ reconstructed in exclusive final states. We observe the $B_{s}^{**0}$, $B^{**0}$ and $B^{**+}$ mesons with light quark orbital momentum $j_q = 3/2$ in the three spectra, respectively, and measure the masses of these states. This provides the first observation of the orbitally excited $B_1^+$ and $B_2^{*+}$ mesons.