## What can we learn from $B\to a_1(1260)(b_1(1235))\pi(K)$ decays?

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Wang, Wei

Li, Run-Hui

Lü, Cai-Dian

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##### Abstract

##### Description

We investigate the $B\to a_1(1260)(b_1(1235))\pi(K)$ decays under the
factorization scheme and find many discrepancies between theoretical
predictions and the experimental data. In the tree dominated processes, large
contributions from color-suppressed tree diagrams are required in order to
accommodate with the large decay rates of $B^-\to a_1^0\pi^-$ and $B^-\to
a_1^-\pi^0$. For $\bar B^0\to (a_1^+, b_1^+)K^-$ decays which are both induced
by $b\to s$ transition, theoretical predictions on their decay rates are larger
than the data by a factor of 2.8 and 5.5, respectively. Large electro-weak
penguins or some new mechanism are expected to explain the branching ratios of
$B^-\to b_1^0K^-$ and $B^-\to a_1^-\bar K^0$. The
soft-collinear-effective-theory has the potential to explain large decay rates
of $B^-\to a_1^0\pi^-$ and $B^-\to a_1^-\pi^0$ via a large hard-scattering form
factor $\zeta_J^{B\to a_1}$. We will also show that, with proper charming
penguins, predictions on the branching ratios of $\bar B^0\to (a_1^+,
b_1^+)K^-$ can also be consistent with the data.

Comment: 16 pages, no figure

Comment: 16 pages, no figure

##### Keywords

High Energy Physics - Phenomenology