arXiv subjects

Zhi-Qing Zhang

Publications and source records attributed to Zhi-Qing Zhang.

At least 37 records · Page 2Linked to original sources

arXiv2022

Two- and three-body hadronic decays of charmed mesons involving a tensor meson

We study the quasi-two-body $D\to TP$ decays and the three-body $D$ decays proceeding through intermediate tensor resonances, where $T$ and $P$ denote tensor and pseudoscalar mesons, respectively. We employ $D\to T$ transition form factors based upon light-cone sum rules and the covariant light-front quark model to evaluate the decay rates, with the former giving a better agreement with current data. Though the tree amplitudes with the emitted meson being a tensor meson vanish under factorization approximation, contributions proportional to the tensor decay constant $f_T$ can be produced from vertex and hard spectator-scattering corrections. We also investigate the finite-width effects of the tensor mesons and find that, contrary to three-body $B$ decays, the tensor-mediated $D$ decays are more seriously affected and the narrow width approximation has to be corrected. More experimental data are required in order to extract information topological amplitudes associated with quasi-two-body $D\to TP$ decays. Among the data, the $D^+\to f_2π^+$ and $D^+\to \bar K_2^{*0}π^+$ branching fractions are not self consistent and further clarification is called for.

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arXiv2022

Hadronic three-body D decays mediated by scalar resonances

We study the quasi-two-body $D\to SP$ decays and the three-body $D$ decays proceeding through intermediate scalar resonances, where $S$ and $P$ denote scalar and pseudoscalar mesons, respectively. Our main results are: (i) Certain external and internal $W$-emission diagrams with the emitted meson being a scalar meson are na{ï}vely expected to vanish, but they actually receive contributions from vertex and hard spectator-scattering corrections beyond the factorization approximation. (ii) For light scalars with masses below or close to 1~GeV, it is more sensible to study three-body decays directly and compare with experiment as the two-body branching fractions are either unavailable or subject to large finite-width effects of the scalar meson. (iii) We consider the two-quark (scheme I) and four-quark (scheme II) descriptions of the light scalar mesons, and find the latter generally in better agreement with experiment. This is in line with recent BESIII measurements of semileptonic charm decays that prefer the tetraquark description of light scalars produced in charmed meson decays. (iv) The topological amplitude approach fails here as the $D\to SP$ decay branching fractions cannot be reliably inferred from the measurements of three-body decays, mainly because the decay rates cannot be factorized into the topological amplitude squared and the phase space factor. (v) The predicted rates for $D^0\to f_0 P, a_0 P$ are generally smaller than experimental data by one order of magnitude, presumably implying the significance of $W$-exchange amplitudes. (vi) The $W$-annihilation amplitude is found to be very sizable in the $SP$ sector with $|A/T|_{SP}\sim 1/2$, contrary to its suppression in the $PP$ sector with $|A/T|_{PP}\sim 0.18$.

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arXiv2021

Probing $D^*_{s0}(2317)$ in the decays of $B$ to two charmed mesons

We probe the inner structure of the meson $D^*_{s0}(2317)$ through the decays of $B_{(s)}$ to two charmed mesons within pQCD approach. Assuming $D^*_{s0}(2317)$ as a scalar meson with $\bar cs$ structure, we find that the predictions for the branching ratios of the decays $B^+\to D^{*+}_{s0}(2317)\bar D^{(*)0}, B^0\to D^{*+}_{s0}(2317)D^{(*)-}$ can explain data within errors. The branching ratios for the decays $B_s\to D^{*+}_{s0}(2317)D_s^{(*)+}$ are estimated to reach up to $10^{-3}$ order, which can be observed by the present LHCb and SuperKEKB experiments. In this work, the decay constant of the meson $D^*_{s0}(2317)$ is an input parameter. Unfortunately, its value has been studied by many references but with large uncertainties. Our calculation shows that a smaller decay constant of the meson $D^*_{s0}(2317)$ is supported by compared with the present data, say $55\sim70$ MeV. We also calculate the ratios $R_1=\frac{Br(B^+\to D^{*+}_{s0}(2317)\bar D^0)}{Br(B^+\to D^{*+}_{s0}(2317)\bar D^{*0})})$ and $R_2=\frac{Br(B^0\to D^{*+}_{s0}(2317)D^-)}{Br(B^0\to D^{*+}_{s0}(2317)D^{*-})}$, which are valuable to determine the inner structure of $D^*_{s0}(2317)$ by compared with the experimental results. Our predictions for the ratios $R_{1,2}$ are consistent with the present data within errors.We expect that these two ratios can be well measured by the future experiments through improving the measurement accuracy for the decays $B^+\to D^{*+}_{s0}(2317)\bar D^{*0}$ and $B^0\to D^{*+}_{s0}(2317)D^{*-}$.

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arXiv2020

Next-to-Leading-logarithm threshold resummation for exclusive $B$ meson decays

We extend the threshold resummation of the large logarithms $\ln x$ which appear in factorization formulas for exclusive $B$ meson decays, $x$ being a spectator momentum fraction, to the next-to-leading-logarithm (NLL) accuracy. It is shown that the NLL resummation effect provides suppression in the end-point region with $x\sim 0$ stronger than the leading-logarithm (LL) one, and thus improves perturbative analyses of the above processes. We revisit the $B\to Kπ$ decays under the NLL resummation, and find that it induces 20-25\% variation of the direct CP asymmetries compared to those from the LL resummation. Our way to avoid the Landau singularity in the inverse Mellin transformation causes little theoretical uncertainty.

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arXiv2019

$B_{(s)}\to D^*_{s0}(2317)P(V)$ decays in perturbative QCD approach

In this work, we use pQCD approach to calculate 20 $B_{(s)}\to D^*_{s0}(2317)P(V)$ two body decays by assuming $D^*_{s0}(2317)$ as a $\bar cs$ scalar meson, where $P(V)$ denotes a pseudoscalar (vector) meson. These $B_{(s)}$ decays can serve as an ideal platform to probe the valuable information on the inner structure of the charmed-strange meson $D^*_{s0}(2317)$, and to explore the dynamics of strong interactions and signals of new physics. These considered decays can be divided into two types: the CKM favored decays and the CKM suppressed decays. The former are induced by $b\to c$ transition, whose branching ratios are larger than $10^{-5}$. The branching fraction of the decay $\bar B^0_s\to D^{*+}_{s0}(2317)ρ^{-}$ is the largest and reaches about $1.8\times 10^{-3}$, while the branching ratios for the decay $\bar B^0_s\to D^{*+}_{s0}(2317)K^{*-}$ and other two pure annihilation decays $\bar B^0\to D^{*+}_{s0}(2317)K^-, D^{*+}_{s0}(2317)K^{*-}$ are only at $10^{-5}$ order. Our predictions are consistent well with the results given by the light cone sum rules approach. These decays are most likely to be measured at the running LHCb and the forthcoming SuperKEKB. The latter are induced by $b\to u$ transition, among of which the channel $\bar B^0\to D^{*-}(2317)ρ^+$ has the largest branching fraction, reaching up to $10^{-5}$ order. Again the pure annihilation decays $B^-\to D^{*-}_{s0}(2317)ϕ, \bar B^0\to D^{*-}_{s0}(2317)K^+(K^{*+}), B^-\to D^{*-}_{s0}(2317)K^0(K^{*0})$, have the smallest branching ratios, which drop to as low as $10^{-10}\sim10^{-8}$.

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arXiv2018

Three body radiative decay $B_s\to ϕ\bar K^0 γ$ in the PQCD approach

We study the three body radiative decay $B_s\to ϕ\bar K^0 γ$ by introducing the $ϕK$ pair distribution amplitudes (DAs) in the perturbative QCD approach. This nonperturbative inputs, the two meson DAs, is very important to simplify the calculations. Besides the dominant electromagnetic penguin operator $O_{7γ}$, the subleading contributions from chromomagnetic penguin operator $O_{8g}$, quark-loop corrections and annihilation type amplitudes are also considered. We find that the branching ratio for the decay $B_s\to ϕ\bar K^0 γ$ is about $(9.26^{+1.79+3.12+0.64}_{-1.61-3.86-0.49})\times10^{-8}$, which is much smaller compared with that for the decay $B^0\to ϕK^0γ$. It is mainly because that the former decay induces by $b\to dγ$ with small CKM matrix element being proportional to $λ^3$. The prediction for the direct CP asymmetry is $A^{dir}_{CP}(B_s\to ϕ\bar K^0 γ)=(-4.1^{+0.4+1.7+0.2}_{-0.6-1.2-0.1})\%$, which is well consistent with the result from the U-spin symmetry approach. we also predict the $B_s \toϕ\bar K^0γ$ decay spectrum, which exhibits a maximu at the $ϕK$ invariant masss around 1.95 GeV.

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arXiv2018

Study of the $K_1(1270)-K_1(1400)$ mixing in the decays $B\to J/ΨK_1(1270), J/ΨK_1(1400)$

We studied the B meson decays $B\to J/ΨK_1(1270,1400)$ in the pQCD approach beyond the leading order. With the vertex corrections and the NLO Wilson coefficients included, the branching ratios of the considered decays are $Br(B^+\to J/ΨK_1(1270)^+)=1.76^{+0.65}_{-0.69}\times10^{-3}, Br(B^+\to J/ΨK_1(1400)^+)=7.03^{+2.70}_{-2.52}\times10^{-4}$, and $Br(B^0\to J/ΨK_1(1270)^0)=(1.63^{+0.60}_{-0.64})\times10^{-3}$ with the mixing angle $θ_{K_1}=33^\circ$, which can agree well with the data or the present experimental upper limit within errors. So we support the opinion that $θ_{K_1}\sim33^\circ$ is much more favored than $58^{\circ}$. Furthermore, we also give the predictions for the polarization fractions, direct CP violations from the different polarization components, the relative phase angles for the considered decays with the mixing angle $θ_{K_1}=33^\circ$ and $58^\circ$, respectively. The direct CP violations of the two charged decays $B^+\to J/ΨK_1(1270,1400)^+$ are very small $(10^{-4}\sim10^{-5})$, because there is no weak phase until up to $\mathcal{O}(λ^4)$ with the Wolfenstein parameter $λ=0.22537$. These results can be tested at the running LHCb and forthcoming Super-B experiments.

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arXiv2017

The decays $B\to Ψ(2S)π(K),η_c(2S)π(K)$ in the pQCD approach beyond the leading-order

Two body $B$ meson decays involving the radially excited meson $ψ(2S)/η_c(2S)$ in the final states are studied by using the perturbative QCD (pQCD) approach. We find that: (a) The branching ratios for the decays involving $K$ meson are predicted as $Br(B^+\toψ(2S)K^+)=(5.37^{+1.85}_{-2.22})\times10^{-4}, Br(B^0\toψ(2S)K^0)=(4.98^{+1.71}_{-2.06})\times10^{-4}, Br(B^+\toη_c(2S)K^+)=(3.54^{+3.18}_{-3.09})\times10^{-4}$, which are consistent well with the present data when including the next-to-leading-order (NLO) effects. Here the NLO effects are from the vertex corrections and the NLO Wilson coefficients. The large errors in the decay $B^+\toη_c(2S)K^+$ are mainly induced by using the decay constant $f_{η_c(2S)}=0.243^{+0.079}_{-0.111}$ GeV with large uncertainties. (b) While there seems to be some room left for other higher order corrections or the non-perturbative long distance contributions in the decays involving $π$ meson, $Br(B^+\toψ(2S)π^+)=(1.17^{+0.42}_{-0.50})\times10^{-5}, Br(B^0\toψ(2S)π^0)=0.54^{+0.20}_{-0.23}\times10^{-5}$, which are smaller than the present data. The results for other decays can be tested at the running LHCb and forthcoming Super-B experiments. (c) There is no obvious evidence of the direct CP violation being seen in the decays $B\to ψ(2S)π(K), η_c(2S)π(K)$ in the present experiments, which is supported by our calculations. If a few percent value is confirmed in the future , it would indicate new physics definitely.

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arXiv2016

Direct CP Violation in Charmless Three-body Decays of $B$ Mesons

Direct CP violation in charmless three-body hadronic decays of $B$ mesons is studied within the framework of a simple model based on the factorization approach. Three-body decays of heavy mesons receive both resonant and nonresonant contributions. Dominant nonresonant contributions to tree-dominated and penguin-dominated three-body decays arise from the $b\to u$ tree transition and $b\to s$ penguin transition, respectively. The former can be evaluated in the framework of heavy meson chiral perturbation theory with some modification, while the latter is governed by the matrix element of the scalar density $\langle M_1M_2|\bar q_1 q_2|0\rangle$. Strong phases in this work reside in effective Wilson coefficients, propagators of resonances and the matrix element of scalar density. In order to accommodate the branching fraction and CP asymmetries observed in $B^-\to K^-π^+π^-$, the matrix element $\langle Kπ|\bar sq|0\rangle$ should have an additional strong phase, which might arise from some sort of power corrections such as final-state interactions. We calculate inclusive and regional CP asymmetries and find that nonresonant CP violation is usually much larger than the resonant one and that the interference effect is generally quite significant. If nonresonant contributions are turned off in the $K^+K^-K^-$ mode, the predicted CP asymmetries due to resonances will be wrong in sign when confronted with experiment. In our study of $B^-\to π^-π^+π^-$, we find that ${\cal A}_{C\!P}(ρ^0π^-)$ should be positive in order to account for CP asymmetries observed in this decay. However, all theories predict a large and negative CP violation in $B^-\to ρ^0π^-$. Measurements of CP-asymmetry Dalitz distributions put very stringent constraints on the theoretical models. We check the magnitude and the sign of violation in some (large) invariant mass regions to test our model.

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arXiv2016

Insight into $f_0(980)$ through the $B_{(s)}$ charmed decays

Through analyzing the $B_{(s)}$ charmed decays $B^{0}\to \bar D_{0}f_0(980)$ and $B_{s}\to \bar D_{0}f_0(980)$ within the framework of the PQCD factorization approach and comparing with the current data, we find that there are two possible regions for the $f_0(980)-f_0(500)$ mixing angle $θ$: one is centered at $34^\circ\sim38^\circ$ and the other is falls into $142^\circ\sim154^\circ$. The former can overlap mostly with one of allowed angle regions extracted from the decay $B^{0}\to \bar D_{0}f_0(500)$. The branching fractions of $B_s$ decay modes are less sensitive to the mixing angle compared with those of B decay modes. Especially, for the decay $B_{s}\to D^0 f_0(980)$, its branching fraction changes only slightly between $(1.2\sim1.8)\times10^{-7}$ when the mixing angle $θ$ runs from $0^\circ$ to $180^\circ$. All of our results support the picture that the $f_0(980)$ is dominated by two quark component in the B decay dynamic mechanism. Furthermore, the $s\bar s$ component is more important than the $q\bar q=(u\bar u+d\bar d)/\sqrt{2}$ component. This point is different from $f_0(500)/σ$. Last but not least, our picture is not in conflict with the popular four-quark explanation.

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arXiv2014

B\to K_1π(K) decays in the perturbative QCD approach

Within the framework of the perturbative QCD approach, we study the two-body charmless decays $B\to K_1(1270)(K_1(1400))π(K)$. We find the following results: (i) The decays $\bar B^0\to K_1(1270)^+π^-, K_1(1400)^+π^-$ are incompatible with the present experimental data. There exists a similar situation for the decays $\bar B^0\to a_1(1260)^+K^-, b_1(1235)^+K^-$, which are usually considered that the nonperturbative contributions are needed to explain the data. But the difference is that the nonperturbative contributions seem to play opposite roles in these two groups of decays.(ii) The pure annihilation type decays $\bar B^0\to K_1^{\pm}(1270)K^{\mp}, K_1^{\pm}(1400)K^{\mp}$ are good channels to test whether an approach can be used to calculate correctly the strength of the penguin-annihilation amplitudes. Their branching ratios are predicted at $10^{-7}$ order, which are larger than the QCDF results. (iii) The dependence of the direct CP-violating asymmetries of these decays on the mixing angle $θ_{K_1}$ are also considered.

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arXiv2014

Analysis of $B \to a_1(1260)(b_1(1235))K^*$ decays in the perturbative QCD approach

Within the framework of perturbative QCD approach, we study the charmless two-body decays $B\to a_1(1260)K^*, b_1(1235)K^*$. 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) Our predictions for the branching ratios are consistent well with the QCDF results within errors, but much larger than the naive factorization approach calculation values. (b) We predict that the anomalous polarizations occurring in the decays $B\to ϕK^*, ρK^*$ also happen in the decays $B\to a_1K^*$, while do not happen in the decays $B\to b_1K^*$. Here the contributions from the annihilation diagrams play an important role to explain the lager transverse polarizations in the decays $B\to a_1K^*$, while they are not sensitive to the polarizations in decays $B\to b_1K^*$. (c) Our predictions for the direct CP-asymmetries agree well with the QCDF results within errors. The decays $\bar B^0\to b^{+}_1K^{*-}, B^-\to b^{0}_1K^{*-}$ have larger direct CP-asymmetries, which could be measured by the present LHCb experiments.

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arXiv2013

Revisiting charmless hadronic B decays to scalar mesons

Hadronic charmless B decays to scalar mesons are studied within the framework of QCD factorization (QCDF). Considering two different scenarios for scalar mesons above 1 GeV, we find that the data favor the scenario in which the scalars $a_0(1450)$ and $K_0^*(1430)$ are the lowest lying $q\bar q$ bound states. This in turn implies a preferred four-quark nature for light scalars below 1 GeV. Assuming $K_0^*(1430)$ being a lowest lying $q\bar s$ state, we show that the data of $B\to K_0^*(1430)η^{(')}$ and $B\to K_0^*(1430)(ρ,ω,ϕ)$ can be accommodated in QCDF without introducing power corrections induced from penguin annihilation, while the predicted $B^-\to \ov K_0^{*0}(1430)π^-$ and $\ov B^0\to K_0^{*-}(1430)π^+$ are too small compared to experiment. In principle, the data of $K_0^*(1430)π$ modes can be explained if penguin-annihilation induced power corrections are taken into account. However, this will destroy the agreement between theory and experiment for $B\to K_0^*(1430)(η^{(')},ρ,ω,ϕ)$. Contrary to the pseudoscalar meson sector where $B\to Kη'$ has the largest rate in 2-body decays of the $B$ meson, we show that $Br(B\to K_0^*η')<\B(B\to K_0^*η)$. The decay $\ov B^0\to a_0(980)^+K^-$ is found to have a rate much smaller than that of $\ov B^0\to a_0(980)^+π^-$ in QCDF, while it is the other way around in pQCD. Experimental measurements of these two modes will help discriminate between these two different approaches. Assuming 2-quark bound states for $f_0(980)$ and $f_0(500)$, the observed large rates of $f_0(980)K$ and $f_0(980)K^*$ modes can be explained in QCDF with the $f_0(980)\!-\!f_0(500)$ mixing angle $θ$ in the vicinity of $20^\circ$.

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arXiv2012

Branching Ratio and Polarization of B \to a_1(1260)(b_1(1235))ρ(ω, ϕ) Decays in the PQCD Approach

Within the framework of perturbative QCD approach, we study the charmless two-body decays into final states involving one axial-vector (A), $a_1(1260)$ or $b_1(1235)$, and one vector (V), namely $ρ(ω,ϕ)$. 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) Except the decays $\bar B^0\to a^{0}_1ρ^0(ω)$, other tree-dominated decays $B\to a_1ρ(ω)$ have larger branching ratios, at the order of $10^{-5}$. (b)Except the decays $\bar B\to b^+_1ρ^-$ and $B^-\to b^0_1ρ^-$, other $B\to b_1ρ(ω)$ decays have smaller branching ratios, at the order of $10^{-6}$. (c) The decays $B\to a_1(b_1) ϕ$ are highly suppressed and have very small branching ratios, at the order of $10^{-9}$. (d) For the decays $\bar B^0 \to a_1^0ρ^0$ and $B^-\to b_1^-ρ^0$, their two transverse polarizations are larger than their longitudinal polarizations, which are about 43.3% and 44.9%, respectively. (d) The two transverse polarizations have near values in the decays $B\to a_1ρ(ω)$, while have large differences in some of $B\to b_1ρ(ω)$ decays. (e) For the decays $B^-\to a^{0}_1ρ^-, b^{0}_1ρ^-$ and $\bar B^0\to b^{0}_1ρ^0, b^{0}_1ω$, where the transverse polarization fractions range from 4.7 to 7.5%, we calculate their direct CP-violating asymmetries with neglecting the transverse polarizations and find that those for two charged decays have smaller values, which are about 11.8% and -3.7%, respectively.

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arXiv2012

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 $\bar B^0_s\to a_1(b_1)ρ$ except the decays $\bar B^0_s\to a_1π$ 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 $\bar B^0_s\to a^0_1(b^0_1)ω$ are the smallest and fall in the order of $10^{-8}\sim10^{-9}$. (c)The branching ratios and the direct CP-asymmetries of decays $\bar B^0_s\to a^0_1(b_1^0)η^{(\prime)}$ are very sensitive to take different Gegenbauer moments for $η^{(\prime)}$. (d) Except for the decays $\bar B^0_s\to a^{0}_1 K^{*0}, a^{0}_1ω, b^{0}_1ω$, 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.

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arXiv2012

Branching Ratio and CP Asymmetry of B_s \to K^*_0(1430)πDecays in the PQCD Approach

In the two-quark model supposition for $K_0^{*}(1430)$, the branching ratios and the direct CP-violating asymmetries for decays $\bar B_s^0\to K^{*0}_0(1430)π^0, K^{*+}_0(1430)π^-$ are studied by employing the perturbative QCD factorization approach. We find that although these two decays are both tree-dominated, the ratio of their penguin to tree contributions are very different: there is only a few percent for the decay $\bar B_s^0\to K^{*+}_0(1430)π^-$, while about 37% in scenario I, even 51% in scenario II for the decay $\bar B_s^0\to K^{*0}_0(1430)π^0$. It results that these two decays have very different values in the branching ratios and the direct CP asymmetries. The branching ratio of the decay $\bar B_s^0\to K^{*+}_0(1430)π^-$ is at the order of $10^{-5}$, and its direct CP asymmetry is about (20-30)%. While for the decay $\bar B_s^0\to K^{*0}_0(1430)π^0$, its direct CP-violating asymmetry is very large and about 90%, but it is difficult to measure it, because the branching ratio for this channel is small and only $10^{-7}$ order.

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arXiv2011

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.

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arXiv2011

Branching Ratio and CP Asymmetry of B_s \to K^*_0(1430)ρ(ω,ϕ) Decays in the PQCD Approach

In the two-quark model supposition for $K_0^{*}(1430)$, 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 $\bar B_s^0\to K^{*0}_0(1430)ϕ, K^{*0}_0(1430)ω, K^{*0}_0(1430)ρ^0, K^{*+}_0(1430)ρ^-$ are studied by employing the perturbative QCD factorization approach. We find the following results: (a) Enhanced by the color allowed tree amplitude with large Wilson coefficients $a_1=C_2+C_1/3$, the branching ratio of $\bar B_s^0\to K^{*+}_0(1430)ρ^-$ is much larger than those of the other three decays and arrives at $(3.4^{+0.8}_{-0.7})\times 10^{-5}$ in scenario I, even $10^{-4}$ order in scenario II, and its direct CP violating asymmetry is the smallest, around 10%, so this channel might be measurable in the current LHC-b experiments, where a large number (about $10^{12}$) of $B$ mesons will be produced per year. This high statistics will make the measurement possible. (b) For the decay modes $\bar B^0_s\to K^{*0}_0(1430)ω, K^{*0}_0(1430)ρ^0$, their direct CP-violating asymmetries are large, but it might be difficult to measure them, because their branching ratios are small and less than (or near) $10^{-6}$ in both scenarios. For example, in scenario I, these values are ${\cal B}(\bar B_s^0\to K^*_0(1430)ω)=(8.2^{+1.8}_{-1.7})\times 10^{-7}, {\cal B}(\bar B_s^0\to K^*_0(1430)ρ^0)=(9.9^{+2.1}_{-2.0})\times 10^{-7}, \acp^{dir}(\bar B^0_s\to K^{*0}_0(1430)ω)=-24.1^{+2.8}_{-2.5}, \acp^{dir}(\bar B^0_s\to K^{*0}_0(1430)ρ^0)=26.6^{+2.5}_{-2.5}.$ (c) For the decay $\bar B^0_s\to K^*_0(1430)ϕ$, the predicted branching ratios are also small and a few times $10^{-7}$ in both scenarios; there is no tree contribution at the leading order, so its direct CP-violating asymmetry is naturally zero.

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