Study of scalar meson f_0(980) and K_0^*(1430) from B \to f_0(980)\rho(\omega, \phi) and B \to K^*_0(1430)\rho(\omega) Decays

In the two-quark model supposition for $f_0(980)$ and $K_0^{*}(1430)$, the branching ratios and the direct CP-violating asymmetries for decays $\bar{B}^0\to f_0(980)\rho^0(\omega,\phi), K^{*0}_0(1430)\rho^0(\omega), K^{*-}_0(1430)\rho^+$ and $B^-\to f_0(980)\rho^-, K^{*0}_0(1430)\rho^-, K^{*-}_0(1430)\rho^0(\omega)$ are studied by employing the perturbative QCD (PQCD)factorization approach. we find the following results: (a) if the scalar meson $f_0(980)$ is viewed as a mixture of $s\bar s$ and $(u\bar u+d\bar d)/\sqrt{2}$, the branching ratios of the decays $\bar{B}^0\to f_0(980)\rho^0(\omega,\phi)$ and $B^-\to f_0(980)\rho^-$, which are induced by $b\to d$ transition, are smaller than the currently experimental upper limits, and the predictions for the decay $\bar{B}^0\to f_0(980)\omega, B^-\to f_0(980)\rho^-$ are not far away from their limits; (b) in the decays $B\to K^*_0(1430)\rho(\omega)$, which are induced by $b\to s$ transition, the branch ratio of $\bar B^0\to K^{*0}_0(1430)\rho^0$ is the smallest one in two scenarios, at the order of $10^{-7}$ for scenario I, about $4.8\times10^{-6}$ for scenario II; (c) the direct CP-asymmetries of the decays $B\to f_0(980)\rho(\omega)$ have a strong dependent on the mixing angle $\theta$: they are large in the range of $25^\circ<\theta<40^\circ$, and small in the range of $140^\circ<\theta<165^\circ$, while the direct CP-asymmetries of the decays $B\to K^{*}_0(1430)\rho(\omega)$ are not large in both scenarios and most of them are less than 20% in size.Comment: 17 pages, 5 figures, minor corrections, typos removed, accepted for publication in Phys. Rev.

clcNet: Improving the Efficiency of Convolutional Neural Network using Channel Local Convolutions

Depthwise convolution and grouped convolution has been successfully applied to improve the efficiency of convolutional neural network (CNN). We suggest that these models can be considered as special cases of a generalized convolution operation, named channel local convolution(CLC), where an output channel is computed using a subset of the input channels. This definition entails computation dependency relations between input and output channels, which can be represented by a channel dependency graph(CDG). By modifying the CDG of grouped convolution, a new CLC kernel named interlaced grouped convolution (IGC) is created. Stacking IGC and GC kernels results in a convolution block (named CLC Block) for approximating regular convolution. By resorting to the CDG as an analysis tool, we derive the rule for setting the meta-parameters of IGC and GC and the framework for minimizing the computational cost. A new CNN model named clcNet is then constructed using CLC blocks, which shows significantly higher computational efficiency and fewer parameters compared to state-of-the-art networks, when being tested using the ImageNet-1K dataset. Source code is available at https://github.com/dqzhang17/clcnet.torch

Study of scalar meson a_0(1450) from B \to a_0(1450)K^* Decays

In the two-quark model supposition for the meson $a_0(1450)$, which can be viewed as either the first excited state (scenario I) or the lowest lying state (scenario II), the branching ratios and the direct CP-violating asymmetries for decays $B^-\to a^{0}_0(1450)K^{*-}, a^{-}_0(1450)K^{*0}$ and $\bar B^0\to a^{+}_0(1450)K^{*-}, a^{0}_0(1450)\bar K^{*0}$ are studied by employing the perturbative QCD factorization approach. We find the following results: (a) For the decays $B^-\to a^{-}_0(1450)K^{*0}, \bar B^0\to a^{+}_0(1450)K^{*-}, a^{0}_0(1450)\bar K^{*0}$, their branching ratios in scenario II are larger than those in scenario I about one order. So it is easy for the experiments to differentiate between the scenario I and II for the meson $a_0(1450)$. (b)For the decay $B^-\to a^{0}_0(1450)K^{*-}$, due to not receiving the enhancement from the $K^*-$emission factorizable diagrams, its penguin operator contributions are the smallest in scenario II, which makes its branching ratio drop into the order of $10^{-6}$. Even so, its branching ratio in scenario II is still larger than that in scenario I about 2.5 times. (c) Even though our predictions are much larger than those from the QCD factorization results, they are still consistent with each other within the large theoretical errors from the annihilation diagrams. (d) We predict the direct CP- violating asymmetry of the decay $B^-\to a^{-}_0(1450)K^{*0}$ is small and only a few percent.Comment: 15 Pages, 5 Figure

Perturbative QCD for B_s \to a_1(1260)(b_1(1235))P(V) Decays

Within the framework of perturbative QCD approach, we study the charmless two-body decays $B_s \to a_1(1260)(b_1(1235))P(V)$ ($P, V$ represent the light pseudo-scalar and vector mesons, respectively.). Using the decays constants and the light-cone distribution amplitudes for these mesons derived from the QCD sum rule method, we find the following results: (a) The decays $\bar B^0_s\to a^{-}_1K^{+}(K^{*+})$ have the contributions from the factorization emission diagrams with a large Wilson coefficient $C_2+C_1/3$ (order of 1), so they have the largest branching ratios and arrive at $10^{-5}$ order. While for the decays $\bar B^0_s\to a^{0}_1 K^{0}(K^{*0})$, the Wilson coefficient is $C_1+C_2/3$ in tree level and color suppressed, so their branching ratios are small and fall in the order of $10^{-7}\sim10^{-8}$. For the decays $\bar B^0_s\to b_1K(K^*)$, all of their branching ratios are of order few times $10^{-6}$. (b) For the pure annihilation type decays $\bar B^0_s\to a_1(b_1)\rho$ except the decays $\bar B^0_s\to a_1\pi$ having large branching ratios of order few times $10^{-6}$, the most other decays have the branching ratios of $10^{-7}$ order. The branching ratios of the decays $\bar B^0_s\to a^0_1(b^0_1)\omega$ are the smallest and fall in the order of $10^{-8}\sim10^{-9}$. (c)The branching ratios and the direct CP-asymmetries of decays $\bar B^0_s\to a^0_1(b_1^0)\eta^{(\prime)}$ are very sensitive to take different Gegenbauer moments for $\eta^{(\prime)}$. (d) Except for the decays $\bar B^0_s\to a^{0}_1 K^{*0}, a^{0}_1\omega, b^{0}_1\omega$, the longitudinal polarization fractions of other $\bar B^0_s\to a_1(b_1)V$ decays are very large and more than 90%. (e) Compared with decays $\bar B^0_s\to a_1(b_1)P$, most of $\bar B^0_s\to a_1(b_1)V$ decays have smaller direct CP asymmetries.Comment: 17 pages, 5 figure