Measurement of the $B^0\to K_2^{*}(1430{)}^0\gamma$ and $B^{+}\to K_2^{*}(1430{)}^{+}\gamma$ branching fractions

We have investigated the exclusive, radiative $B$ meson decays to $K_2^{*}(1430)$ in $89\times {10}^6$ $B\overline{B}$ events with the BABAR detector at the PEP-II storage ring. We measure the branching fractions $\mathcal{B}(B^0\to K_2^{*}(1430{)}^0\gamma )=(1.22\pm 0.25\pm 0.10)\times {10}^{-5}$ and $\mathcal{B}(B^{+}\to K_2^{*}(1430{)}^{+}\gamma )=(1.45\pm 0.40\pm 0.15)\times {10}^{-5}$, where the first error is statistical and the second systematic. In addition, we measure the $CP$-violating asymmetry ${\mathcal{A}}_{CP}[B^0\to K_2^{*}(1430{)}^0\gamma ]=-0.08\pm 0.15\pm 0.01$.

Figure 1

The cosine of thrust angle (a) and neural network output (b) distributions of the $B\to K_2^{*}(1430)\gamma$ MC simulation (filled circles), the off-resonance data (line), and the continuum background MC (open circles). The vertical line indicates the cut value.

Figure 2

Distributions of (a) $m_{\mathrm{E}\mathrm{S}}$, (b) $\Delta E$, and (c) $|\cos {\theta }_H|$for $B^0\to K_2^{*}(1430{)}^0\gamma$, $K_2^{*}(1430{)}^0\to K^{+}{\pi }^{-}$ candidates in data, and (d) $|\cos {\theta }_H|$ in the signal region. The solid line shows the result of the fit to the data. The peaking (dashed-dotted line) and nonpeaking (dotted line) background contributions are also shown.

Figure 3

Distributions of (a) $m_{\mathrm{E}\mathrm{S}}$, (b) $\Delta E$, and (c) $|\cos {\theta }_H|$ for the $B^{+}\to K_2^{*}(1430{)}^{+}\gamma$, $K_2^{*}(1430{)}^{+}\to K_S^0{\pi }^{+}$ candidates in data, and (d) $|\cos {\theta }_H|$ in the signal region. The solid line shows the result of the fit to the data. The peaking (dashed-dotted line) and nonpeaking (dotted line) background contributions are also shown. The corresponding distributions for $K_2^{*}(1430{)}^{+}\to K^{+}{\pi }^0$ candidates are shown in (e–h).

Figure 4

(a) $K^{+}{\pi }^{-}$ and (b) $K_S^0{\pi }^{+}$ and $K^{+}{\pi }^0$ invariant mass distributions for the signal region (see text) after background subtraction.