Measurement of theB+production cross section inpp¯collisions ats=1960GeV

We present a new measurement of the $B^{+}$ meson differential cross section $d\sigma /d{p}_T$ at $\sqrt{s}=1960\mathrm{GeV}$. The data correspond to an integrated luminosity of $739{\mathrm{pb}}^{-1}$ collected with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider. $B^{+}$ candidates are reconstructed through the decay $B^{+}\to J/\psi K^{+}$, with $J/\psi \to {\mu }^{+}{\mu }^{-}$. The integrated cross section for producing $B^{+}$ mesons with $p_T\ge 6\mathrm{GeV}/c$ and $|y|\le 1$ is measured to be $2.78\pm 0.24\mu \mathrm{b}$.