We report a measurement of resonance parameters of the orbitally excited ($L=1$) narrow $B^0$ mesons in decays to $B^{(*)+}{\pi }^{-}$ using $1.7{\mathrm{fb}}^{-1}$ of data collected by the CDF II detector at the Fermilab Tevatron. The mass and width of the $B_2^{*0}$ state are measured to be $m(B_2^{*0})={5740.2}_{-1.8}^{+1.7}(\mathrm{stat}{)}_{-0.8}^{+0.9}(\mathrm{syst})\mathrm{MeV}/c^2$ and $\Gamma (B_2^{*0})={22.7}_{-3.2}^{+3.8}(\mathrm{stat}{)}_{-10.2}^{+3.2}(\mathrm{syst})\mathrm{MeV}/c^2$. The mass difference between the $B_2^{*0}$ and $B_1^0$ states is measured to be ${14.9}_{-2.5}^{+2.2}(\mathrm{stat}{)}_{-1.4}^{+1.2}(\mathrm{syst})\mathrm{MeV}/c^2$, resulting in a $B_1^0$ mass of ${5725.3}_{-2.2}^{+1.6}(\mathrm{stat}{)}_{-1.5}^{+1.4}(\mathrm{syst})\mathrm{MeV}/c^2$. This is currently the most precise measurement of the masses of these states and the first measurement of the $B_2^{*0}$ width.

• Received 29 September 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.102003