K. Azizi, H. Sundu, J. Y. Sungu, N. Yinelek
The form factors of the semileptonic $χ_{b2}(1P)\rightarrow B_{c}\bar{l}ν$ decay are calculated using the QCD sum rule approach. The results obtained are then used to estimate the decay widths of this transition in all lepton channels. The orders of decay rates indicate that this transition is accessible at LHC for all lepton channels.
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$CP$ violation for $B^{0}\rightarrow ρ^{0}(ω)ρ^{0}(ω) \rightarrow π^+π^-π^+π^-$ in QCD factorization
在QCD因子分解（QCDF）方法中，我们通过$ρ-ω$混合机制研究了$\bar{B}^{0}\rightarrowρ^0(ω)ρ^0(ω)\rightarrowπ^+π^-π^+π^-$中的直接$CP$破坏.研究发现，当$π^+π^-$对的质量在$ω$共振附近时，$CP$破坏可以被双$ρ-ω$混合增强，最大$CP$破坏可以达到28{\%}.我们还比较了朴素因子分解和QCD因子分解的结果。
We calculate the magnetic dipole and electric quadrupole moments associated with the radiative $Ω_{Q}^{*}\rightarrowΩ_{Q}γ$ and $Ξ_{Q}^{*}\rightarrowΞ^{\prime}_{Q}γ$ transitions with $Q=b$ or $c$ in the framework of light cone QCD sum rules. It is found that the corresponding quadrupole moments are negligibly small while the magnetic dipole moments are considerably large. A comparison of the results on the considered multipole moments as well as corresponding decay widths with the predictions of the vector dominance model is performed.
The strong $D_{2}^{*}(2460)^{0}\rightarrow D^+ π^- $ and $D_{s2}^{*}(2573)^{+}\rightarrow D^{+} K^{0}$ transitions are analyzed via three point QCD sum rules. First, we calculate the corresponding strong coupling constants $g_{D_2^*Dπ}$ and $g_{D_{s2}^*DK}$. Then, we use them to calculate the corresponding decay widths and branching ratios. Making use of the existing experimental data on the ratio of the decay width in the pseudoscaler $D$ channel to that of the vector $D^*$ channel, finally, we estimate the decay width and branching ratio of the strong $D_2^*(2460)^0 \rightarrow D^*(2010)^+π^…
Exclusive $B_c^\ast \rightarrow D_{s}~ν\barν$ decay is studied in the framework of the three--point QCD sum rules approach. The two gluon condensate contributions to the correlation function are calculated and the form factors of this transition are found. The decay width and total branching ratio for this decay is also calculated.
Leading Order QCD Corrections to $b\rightarrow s \, γ$ and $b \rightarrow s \, g$ Decays in Three Regularization Schemes
本文详细讨论了在三种不同的正则化方案（HV，NDR和DRED）下，对支配$b \rightarrow s\, γ$和$b \rightarrow s \, g$跃迁的有效哈密顿量的首阶QCD修正的计算。我们发现，计算的中间阶段依赖于正则化，但相同的计划独立系数可以在所有考虑的计划。已经在文献中给出的结果的详细讨论。
In the perturbative QCD (PQCD) approach we study the direct $CP$ violation in $B^+_{c}\rightarrow D_{(s)}^+ρ^0(ω) \rightarrow D_{(s)}^+π^+π^-$ via the $ρ-ω$ mixing mechanism. We find that the $CP$ violation can be enhanced by $ρ-ω$ mixing when the invariant masses of the $π^+π^-$ pairs are in the vicinity of the $ω$ resonance. For the decay process $B^+_{c}\rightarrow D^+ρ^0(ω) \rightarrow D^+π^+π^-$, the maximum $CP$ violation can reach 7.5 {\%}.
We calculate the direct $CP$ violation for the decay process of ${B}^{0}\rightarrow π^{0}π^{0}$, ${B}^{+}\rightarrow π^{0}π^{+}$, ${B}^{0}\rightarrow K^{0}π^{0}$ and ${B}^{+}\rightarrow K^{+}π^{0}$ via isospin symmetry breaking effects from the $π^{0}-η-η'$ mixing mechanism in perturbative QCD approach. Isospin symmetry breaking originates from the electroweak interaction and the u-d quark mass difference through the strong interaction which are known to be tiny. However, we find that isospin symmetry breaking at the leading order changes the $CP$ violation from the new strong phases. Our calc…
Rare exclusive $B_c^\ast \rightarrow D_{s}~l^+ l^-$ decays are analyzed in the framework of the three--point QCD sum rules approach. The two gluon condensate corrections to the correlation function are included and the form factors of this transition are evaluated. Using the form factors, the decay width and integrated decay rate for these decays are also calculated.
Non-factorization contributions in $D\rightarrow πK, KK$ decay
我们分析了$D\rightarrow πK, KK$衰变的朴素因子分解（NF）、QCD因子分解（QCDF）和包含软胶子交换的QCD因子分解（QCDF+SGE）。在这些衰变通道中，首次采用光锥QCD求和规则计算了软胶子效应。比较这三种方法的计算结果发现，在色抑制衰变道中，QCD因子分解（QCDF）比朴素因子分解（NF）得到了更大的改进，而在色抑制衰变道中，QCD因子分解（QCDF）比包含软胶子交换的QCD因子分解（QCDF+SGE）得到了更大的改进。此外，我们还发现软胶子效应大于首阶贡献，并且对于色抑制的衰变通道，计算结果与实验数据接近。在色允许衰变道$D^{0}\rightarrow π^{+} K^{-}$中，软胶子效应很小，我们应该考虑其他的功率项，如末态相互作用和湮灭效应。
With only the tree level operator, the decay of $Λ_b\rightarrow pK$ is predicted to be one order smaller than the experimental data. The QCD penguin effects should be taken into account. In this paper, we explore the one-loop QCD corrections to the decay of $Λ_b\to pK$ within the framework of QCD factorization approach. For the baryon system, the diquark approximation is adopted. The transition hadronic matrix elements between $Λ_b$ and $p$ are calculated in the light front quark model. The branching ratio of $Λ_b\rightarrow pK$ is predicted to be about $4.85\times 10^{-6}$ which is consistent…
QCD Calculation of the $B \rightarrow π,K$ Form Factors
利用QCD求和规则，利用$π$和$K$光锥波函数计算了重轻跃迁$B\rightarrow π,K $的形状因子.更高的扭曲的贡献，以及胶子修正考虑在内。讨论了超前扭转波函数形状的敏感性和SU（3）破缺的影响。并将结果与夸克模型的预言和QCD求和规则的结果进行了比较。
We analyze the semileptonic $ B_{s} \rightarrow D_{s2}^{*}(2573)\ell\bar{ν}_{\ell}$ transition, where $\ell=τ,~μ$ or $e$, within the standard model. We apply the QCD sum rule approach to calculate the transition form factors entering the low energy Hamiltonian defining this channel. The fit functions of the form factors are used to estimate the total decay widths and branching fractions in all lepton channels. The orders of branching ratios indicate that this transition is accessible at LHCb in near future.
The real radiation antenna functions for $S\rightarrow Q\bar{Q}gg$ at NNLO QCD
在天线减法的框架下，我们分析了在NNLO QCD中无色初态产生一对重夸克和两个胶子的过程的真实辐射天线函数。我们提供这些功能的明确表达，并讨论其红外奇异行为。我们的主要结果是相应的集成天线功能，计算分析。它们用调和多边形来表示。
Improved Light-cone QCD Sum Rule Analysis Of The Rare Decays $Λ_b\rightarrowΛγ$ And $Λ_b\rightarrowΛl^+l^-$
本文在标准模型的框架下，系统地研究了稀有辐射衰变$Λ_b\rightarrowΛγ$和稀有半轻子衰变$Λ_b\rightarrowΛl^+l^-$的光锥QCD求和规则。虽然在不同的文献中可以找到一些关于这些稀有过程的LCSR研究，但由于重子分布振幅的改进或对$Λ_b$重子采用不同的内插流可能导致不同的结果，因此有必要对它们进行系统的重新分析。此外，稀有过程$Λ_b\rightarrowΛγ$还没有被分析的LCSR与Ioffe型电流。考虑到所有这些原因，我们进行LCSR计算的两种类型的插值电流的过程。计算结果表明，$Λ_b$重子的内插电流的选择对预言有很大的影响，特别是对稀有的辐射衰变过程。
Investigation of the $B_c\rightarrow χ_{c2} l \barν $ transition via QCD sum rules
在QCD求和规则的框架下，考虑双胶子凝聚修正，计算了半轻子$B_c\rightarrow χ_{c2} l \barν $的跃迁形状因子。利用所得到的形状因子的结果，我们估计了在所有轻子通道中与这种跃迁有关的衰变宽度和分支比。所得结果与其他非微扰方法的预测进行了比较。不同轻子通道的分支比的顺序表明，$B_c\rightarrow χ_{c2} l \barν $跃迁可以在大型强子对撞机上利用收集到的或将来的数据进行研究。
In the framework of Perturbative QCD (PQCD) approach we study the direct $CP$ asymmetry for the decay channel $\bar{B}_{s}\rightarrow Pπ^+π^-$ around the resonance range via the $ρ-ω$ mixing mechanism (where P refer to pseudoscalar meson). We find that the $CP$ asymmetry can be enhanced by $ρ-ω$ mixing when the masses of the $π^+π^-$ pairs are at the area of $ρ-ω$ resonance, and the maximum $CP$ asymmetry can reach 59{\%} for the relevant decay channels.
Pseuduscalar Heavy Quarkonium Decays With Both Relativistic and QCD Radiative Corrections
通过考虑相对论和QCD辐射修正，我们估计了$η_c\rightarrow 2γ$，$η_c'\rightarrow 2γ$和$J/ψ\rightarrow e^+ e^-$，$ψ^\prime\rightarrow e^+e^-$的衰变率。衰变振幅在Bethe-Salpeter形式主义中导出。用量子色动力学激发的夸克间势的Bethe-Salpeter方程计算了这些$c\bar{c}$态的波函数和衰变宽度。我们发现相对论修正对比值$R\equiv Γ(η_c \rightarrow 2γ)/ Γ(J/ ψ\rightarrow e^+ e^-)$的贡献是负的，并且倾向于补偿QCD辐射修正的正贡献。我们的估计给出了$Γ(η_c \rightarrow 2γ)=(6-7) ~keV$和$Γ(η_c^\prime \rightarrow 2γ)=2 ~keV$，它们小于它们的非相对论值。若为$α_s(m_c)=0.26-0.29$，则对应于一阶QCD辐射修正给出强子宽度$Γ(η_c \rightarrow 2g)=(17-23) ~MeV$和$Γ(η_c^\prime \rightarrow 2g)=(5-7)~MeV$。还估计了$b\bar b$态的衰变宽度。我们证明，当假设夸克在质量壳层上时，衰变宽度的表达式与NRQCD理论中的$v^2$和$α_s$的次一级衰变宽度的表达式是一致的。
In this work, we analyse the CP-averaged branching ratios and direct CP-violating asymmetries of the four-body decays B_{S} \rightarrow ππππdecay from the S-wave resonances, f_{0}(980) and f_{0}(500) and P-wave resonances, ρ(770) by introducing the S-wave and P-wave ππdistribution amplitudes within the framework of the perturbative QCD approach. We also calculate branching ratios of the two-body decays B^{0}_{S}\rightarrowρ^{0}ρ^{0}, B^{0}_{S}\rightarrowρ^{+}ρ^{-} from the corresponding quasi-two-body decays models and compare our results with those obtained in previous perturbative QCD approa…
Effective Lagrangian for $b \rightarrow s$ Processes with QCD-Corrections
本文对$m_t=m_w$和$m_t \gg m_w$两种情形，在主对数近似下，给出了具有$QCD$修正的$b \rightarrow s$过程的有效拉格朗日量的完整计算.然后应用有效拉格朗日量来估计$b \rightarrow s γ$衰减速率。我们发现$m_t=m_w$的情况下，它被增强了6倍，而$m_t \gg m_w$的情况下，它被增强了约2倍。我们的结果与文献中发现的结果不同，但对于$m_t=m_w$，数值上没有很大的不同。
We present the two-loop master integrals relevant to the ${\mathcal O}(αα_s)$-corrections to the decay $H \rightarrow b \bar{b}$ through a $H t \bar{t}$-coupling. We keep the full dependence on the heavy particle masses, but neglect the $b$-quark mass. The occurring square roots can be rationalised and the result is expressed in terms of multiple polylogarithms.
QCD Interconnection Effects \\ in Hadronic $W^+W^-$ and $t\bar{t}$ Events
在$e^+e^- \rightarrow W^+W^- \rightarrow$ 4型喷射器$e^+e^- \rightarrow t\bar{t} \rightarrow bW^+\bar{b}W^-$的情况下，粒子产生可能以非平凡的方式取决于过程的运动学。结果表明，对于高能微扰辐射，QCD干涉效应可以忽略不计，但软微扰胶子和非微扰碎裂可以诱导色关联。LEP 2和NLC事件的可能后果进行了简要讨论。
Within the QCD factorization approach, we study the $CP$ violations in $B^-\rightarrow K^-π^+π^-$ and $B^-\rightarrow K^- f_0(500)$ decays. We find the experimental data of the localized $CP$ asymmetry in $B^-\rightarrow K^-π^+π^-$ decays in the region $m_{K^-π^+}^2<15$ $\mathrm{GeV}^2$ and $0.08<m_{π^+π^-}^2<0.66$ $\mathrm{GeV}^2$ can be explained by the interference of two intermediate resonances, $ρ^0(770)$ and $f_0(500)$ when the parameters in our interference model are in the allowed ranges, i.e. the relative strong phase $δ\in[0, 1.745]\cup[3.578, 6.266]$ and the end-point divergence par…
The isovector axial vector form factors of $N \rightarrow Δ$ transition are calculated by employing Light-cone QCD sum rules. The analytical results are analysed by both the conventional method, and also by a Monte Carlo based approach which allows one to scan all of the parameter space. The predictions are also compared with the results in the literature, where available. Although the Monte Carlo analysis predicts large uncertainties in the predicted results, the predictions obtained by the conventional analysis are in good agreement with other results in the literature.
We investigate $J/ψ$ decays into octet baryon-antibaryons pairs. The decay amplitudes are computed within the collinear QCD factorisation framework. The subleading amplitude, which describes the decay of longitudinally polarised charmonium, is computed using twist-4 three-quark distribution amplitudes. The obtained results are used for a qualitative analysis of the experimental data. It is found that the polarisation parameter $α_B$ can be described with an accuracy $10-30\%$, which may indicate that the pQCD contribution dominates this observable.
Two-loop QCD-corrections to $e^{+} e^{-} \rightarrow Z^{\ast} \rightarrow \boldsymbol{J /ψ}+\boldsymbol{J/ ψ}$
在非相对论性 QCD 框架下计算了 $e^{+}e^{-} \rightarrow Z^{*} \rightarrow J/\psi J/\psi$ 的次次领头阶修正，发现高阶贡献显著放大，并据此预测了 $Z$ 玻色子到双粲偶素和双底偶素末态的衰变宽度。
Decays $J/ψ\to B\bar B$ into octet baryon-antibaryons pairs are studied within the QCD factorisation framework. The next-to-leading power correction to the leading-order decay amplitude is calculated for the first time. The phenomenological analysis also includes the interference with the electromagnetic decay $J/ψ\to γ^*\to B\bar B$. The branching fractions and the angular coefficients $α_B$ are described with an accuracy of about $20\%$. The obtained results allow us to conclude that the calculated amplitudes provide a dominant contribution and therefore QCD factorisation provides a suitable…
Large mass expansion in two-loop QCD corrections of para-charmonium decay
我们计算了对副卡蒙衰变$eta_{c} rightarrow gamma gamma$和$eta_{c} rightarrow g g$的双圈QCD修正，包括含轻夸克圈的光-光散射图。人工大质量扩张和收敛改进技术被用来评估这些修正。对衰变$eta_{c} rightarrow gamma gamma$和$eta_{c} rightarrow g g$的修正分别解释了主阶贡献的$-1.25 %$和$ -0.73 %$。
The $B_c\rightarrow D^{(*)}T$ decays in perturbative QCD approach
在本工作中，我们基于$k_T$因子分解，用微扰QCD方法研究了这些$B_{c}\rightarrow D^{(*)}T$衰变，其中T表示一个轻张量介子。对于所有的衰变考虑在这项工作中，有没有贡献的可因子化的发射图，因为发射介子是张量介子。我们发现，湮没振幅是占主导地位的，在这些衰变由于大Cabibbo-Kobayashi-Maskawa元素，这是唯一的计算在pQCD方法。数值结果表明，大多数衰变的分支比的预测值都在$10^{-6}$量级甚至更大，这在正在进行的实验中是可以观察到的。我们还预测了大比例的横向极化在这些W湮没图占主导地位的$B_{c} \rightarrow D^{*}T$衰变通道。
NLO QCD corrections to $pp\rightarrow e^+ν_eμ^+ν_μjj$ in vector-boson fusion at the LHC
我们报道了对与矢量玻色子融合（VBF）产生中间$W^+W^+$对有关的过程$pp\rightarrow e^+ν_eμ^+ν_μjj$的次领先阶（NLO）QCD修正的研究。的s-通道图和干扰贡献VBF运动学的影响进行了分析，在领先的顺序（LO），发现是完全可以忽略不计的。非线性光学修正约为光学截面的5%，尺度依赖性降低到约1%。我们引入了一个动态标度，提高了K因子的高能量尾部的分布。
CP asymmetry Relations Between $\bar B^0\rightarrow ππ$ and $\bar B^0\rightarrow πK$ Rates
证明了在三代标准模型中CP破坏率差$Δ(\bar B^0 \rightarrow π^+π^-) = Γ(\bar B^0 \rightarrow π^+π^-) - Γ( B^0 \rightarrow π^-π^+)$与$Δ(\bar B^0 \rightarrow π^+ K^-) = Γ(\bar B^0 \rightarrow π^+K^-) - Γ(B^0 \rightarrow π^-K^+)$有关。忽略小的湮灭图，在SU（3）对称极限下，我们得到了$Δ(\bar B^0 \rightarrow π^+π^-) = - Δ(\bar B^0 \rightarrow π^+ K^-)$ .利用因子分解近似估计了SU（3）破缺效应，得到了$Δ(\bar B^0\rightarrow π^+π^-) \approx -(f_π/f_K)^2Δ(\bar B^0 \rightarrow π^+K^-)$ .讨论了这一显着关系在CKM么正三角形中确定相位的正确性。
Nonleptonic two body $B_c$ decays including radially excited $ψ(2S)$ or $η_c(2S)$ mesons in the final state are studied using the perturbative QCD approach based on $k_T$ factorization. The charmonium distribution amplitudes are extracted from the $n = 2, l = 0$ Schr$\ddot{o}$dinger states for the harmonic oscillator potential. Utilizing these distribution amplitudes, we calculate the numerical results of the $B_c\rightarrow ψ(2S),η_c(2S)$ transition form factors and branching fractions of $B_c\rightarrow ψ(2S)π, η_c(2S)π$ decays. The ratio between two decay modes $B_c\rightarrow ψ(2S)π$ and $…
By using the 3-point QCD sum rules, we calculate the transition form factors of $D$ decays into the spin triplet axial vector mesons $a_1(1260)$, $f_1(1285) $, $f_1(1420)$. In the calculations, we consider the quark contents of each meson in detail. In view of the fact that the isospin of $a_1(1260)$ is one, we calculate the $D^+ \rightarrow a_1^0 (1260)$ and $D^0 \rightarrow a_1^- (1260)$ transition form factors separately. In the case of $ f_1(1285), f_1(1420)$, the mixing between light flavor $SU(3)$ singlet and octet is taken into account. Based on the form factors obtained here, we give p…
Comparative analysis of the semileptonic $Λ_b \rightarrow Λ\ell^+ \ell^-$ transition in SM and different SUSY scenarios using form factors from full QCD
计算了标准模型和不同超对称模型中的半轻子$Λ_b\rightarrow Λ\ell^+ \ell^-$跃迁。特别地，考虑到在全QCD中进入低能有效哈密顿量的矩阵元以形状因子的形式参数化，我们计算了超对称模型中该衰变通道的振幅和微分衰变率.然后利用全理论中光锥QCD求和规则计算的形状因子，分析了不同超对称模型下该衰变道的微分分支比和轻子前后不对称性，并与标准模型的结果进行了比较.我们还讨论了不同的超对称模型的结果如何偏离标准模型的预测和超对称性的情况下是有利的。
We study the $B_{c}$$\rightarrow$$ψ(2S)$K, $η_{c}(2S)$K, $ψ(3770)$K decays with perturbative QCD approach (pQCD) based on $k_T$ factorization. The new orbitally excited charmonium distribution amplitudes $ψ(1^{3}D_{1})$ based on the Schrödinger wave function of the $n=1$, $l=2$ state for the harmonic-oscillator potential are employed. By using the corresponding distribution amplitudes, we calculate the branching ratio of $B_{c}$$\rightarrow$$ψ(2S)$K, $η_{c}(2S)$K, $ψ(3770)$K decays and the form factors $A_{0,1,2}$ and $V$ for the transition $B_{c}$$\rightarrow$$ψ(1^{3}D_{1})$. We obtain the br…
Anomalous Dimensions of High Twist Operators in QCD at $N \rightarrow 1$ and large $Q^2
在微扰QCD中，计算了高扭转算符在深度非弹性散射中的反常维数（$γ_{2n}$），即在矩变量$N \rightarrow 1$（或$x_B\rightarrow 0$）的极限下和在大的$Q^2$（双对数近似）下.我们发现在这种近似下$γ_{2n}(N-1)$的值表现为${N_c α_S \over π(N-1)} n^2(1 + {δ\over 3} (n^2-1))$，其中$δ\approx 10^{-2}$。这意味着，高扭曲运营商的贡献引起了更早的发病比以前估计的阴影。推导利用了Pomeron交换近似，Pomeron相互吸引。我们发现它们表现为费米子系统。
Two-Loop QCD Correction to massive spin-2 resonance $\rightarrow$ 3 gluons
我们给出了由于出生振幅和双圈振幅的干涉对过程$h \rightarrow g+g+g$的${\cal O}(α_s^3)$虚QCD修正，其中$h$是一个大质量自旋2粒子，$g$是胶子.我们假设SM场通过SM能量动量张量耦合到$h$。我们的结果构成的成分之一，以充分NNLO QCD的贡献，生产一个大规模的自旋2粒子随着喷流在散射过程中在大型强子对撞机。特别地，这个质量自旋-2可能是大额外维模型中ADD引力子的KK模，或者是扭曲额外维模型中的RS KK模，或者是一般的质量自旋-2。此外，这也为研究由能量动量算符引起的张量耦合的QCD振幅的紫外和红外结构提供了机会。通过维数正则化，我们发现这种振幅的红外极点与Catani提出的张量插入QCD振幅因式分解性质相一致。
Investigation of the $Λ_b \rightarrow Λ\ell^+ \ell^-$ transition in universal extra dimension using form factors from full QCD
利用最近得到的全QCD中的相关形状因子，我们对存在单一普适额外维的Applequist-Cheng-Dobrescu模型中的$Λ_b \rightarrow Λ\ell^+ \ell^-$跃迁进行了全面的分析.特别地，我们用紧化半径和相应的形状因子分析了$Λ$重子的分支比、前后不对称性、双轻子极化不对称性和极化等相关观测量.我们提出的灵敏度，这些可观的紧化参数，1/R高达1/R=1000 GeV。我们还将结果与重夸克有效理论的形状因子和SM预言的结果进行了比较。
Exact $m_{quark}\neq 0$ Condensates in $QCD_{1+1}(N_C\rightarrow \infty)$
在无限色数的极限下，我们导出了$QCD_{1+1}$中夸克凝聚的解析表达式，它是夸克质量和规范耦合常数的函数。对于零夸克质量，得到了非零夸克凝聚。然而，我们证明了没有相变作为夸克质量的函数。进一步证明了$\langle 0 | \overlineψψ|0\rangle$在规范耦合中的展开式收敛半径为零，而微扰级数是有限收敛半径的Borel可和的.非解析行为$\langle 0 | \overlineψψ|0\rangle \stackrel{m_q\rightarrow0}{\sim} - N_C \sqrt{G^2}$只能通过对扰动级数求和到无穷阶得到。
We employ the generalized parton picture to analyze the reaction $π^- p \rightarrow D^- Λ_c^+$. Thereby it is assumed that the process amplitude factorizes into one for the perturbatively calculable subprocess $\bar{u}\ u\rightarrow \bar{c}\ c$ and hadronic matrix elements that can be parameterized in terms of generalized parton distributions for the $π^-\rightarrow D^-$ and $p\rightarrow Λ_c^+$ transitions, respectively. Representing these parton distributions in terms of valence-quark light-cone wave functions for $π$, $D$, $p$ and $Λ_c$ allows us to make numerical predictions for unpolarize…
Resonant contribution of the three-body decay process $\bar B_{s}\rightarrow K^{+}K^{-} P$ in perturbation QCD
本文在微扰QCD框架下研究 $\ar B_s\ o K^+K^-P$ 三体衰变，纳入 $ϕ$、$ρ$、$ω$ 共振干涉与混合，计算准两体振幅并预言显著且局域化的CP破坏，可供LHC未来实验检验。
We make a systematic investigation on the two-body nonleptonic decays $B_c\rightarrow J/Ψ(η_c),M$ by employing the perturbative QCD approach based on $k_T$ factorization, where $M$ is a light pseudoscalar or vector or a heavy charmed meson. We predict the branching ratios and direct CP asymmetries of these $B_c$ decays and also the transverse polarization fractions of $B_c\rightarrow J/ΨV,J/ψD^{*}_{(s)}$ decays. It is found that these decays have a large branching ratios of the order of $10^{-4} - 10^{-2}$ and could be measured by the future LHC-b experiment. Our predictions for the ratios of …
Analysis of the $B_{(s)}\rightarrow T(J^P=2^-)$ transition in light cone QCD sum rules
利用光锥QCD求和规则，计算了味改变中性流诱导的$B_{(s)}$到$J^P=2^-$张量介子跃迁的形状因子及衰变宽度，为未来实验研究提供理论依据。
Predicting $B -> ργ$ and $B_s -> ργ$ using holographic AdS/QCD Distribution Amplitudes for the $ρ$ meson
我们导出了横向极化$ρ$介子的全息AdS/QCD分布振幅，并用它们预测了重夸克极限下超过主导功率精度的$\bar B^\circ\rightarrow ρ^\circ γ$和$\bar B^\circ_s\rightarrow ρ^\circ γ$衰变的分支比.对于$\bar B^\circ\rightarrow ρ^\circ γ$，我们的预测与使用求和规则（SR）分布振幅生成的预测以及来自BaBar和Belle合作的数据一致。在计算$\bar B^\circ\rightarrow ρ^\circ γ$中被功率抑制但在$\bar{B}^{\circ}_s\rightarrow ρ^\circ γ$中占主导地位的弱湮灭振幅时，我们发现，在目前的形式下，AdS/QCD DA避免了SR DA所遇到的端点发散。
We study the $γγ\rightarrow M^{+}M^{-}(M=π, K)$ processes with the contributions from the two-particle twist-2 and twist-3 distribution amplitudes of pion and kaon mesons on BHL prescription in the standard hard-scattering approach. The results show that the contributions from twist-3 parts are actually not power suppressed comparing with the leading-twist contributions and the cross sections agree well with the experimental data in the two-photon center-of-mass energy $W>2.8$ GeV. We also predict the cross section ratio $σ_{0}(π^{+}π^{-})/σ_{0}(K^{+}K^{-})$, which is compatible with the exper…
Rare Radiative $B_{c}\rightarrow D_{s1}(2460)γ$ Transition in QCD
我们在QCD求和规则的框架下研究了辐射$B_{c} \to D_{s1} γ$跃迁。特别是，我们计算的过渡形状因子负责这种衰变在弱湮灭和电磁企鹅通道使用夸克凝聚，混合和双胶子凝聚图以及软夸克在电磁场中的传播作为非微扰修正。这些形状因子然后被用于估计所考虑的信道的分支比。计算得到了$B_{c} \to D_{s1} γ$跃迁的总分支比为$10^{-5}$量级，弱湮没通道对跃迁的贡献占主导地位.
In the framework of perturbative QCD, the radiative decays $J/ψ\rightarrowγη^{(\prime)}$ are revisited in detail, where the involved one-loop integrals are evaluated analytically with the light quark masses kept. We have found that the sum of loop integrals is insensitive to the light quark masses and the branching ratios $\mathcal{B}(J/ψ\rightarrowγη^{(\prime)})$ barely depend on the shapes of $η^{(\prime)}$ distribution amplitudes. With the parameters of $η-η^{\prime}$ mixing extracted from low energy processes and $J/ψ\rightarrowγη^{(\prime)}$ by means of nonperturbative matrix elements $\l…
Study of $B\rightarrow ρη$, $ρη^{\prime}$ decays in the modified perturbative QCD approach
本文在改进的微扰QCD方法中引入软跃迁形状因子和色八重态长距离贡献，研究了 $B\rightarrow ρη$、$ρη^{\prime}$ 衰变，所得分支比与 $CP$ 破坏结果和实验一致，并给出了可被未来实验检验的新预言。
The nonleptonic two-body $Λ_b\rightarrow Λψ$ decays with $ψ=J/ψ$ or $ψ(2S)$ are investigated based on the perturbative QCD approach. These are color-suppressed processes in which the nonfactorizable contributions are confirmed to be dominant. Angular momentum conservation allows us to describe the concerned decays by four independent complex helicity amplitudes. It is observed that the negative-helicity states for the $Λ$ baryon are preferred as expected in the left-handed nature of the charged-current interaction. The obtained results for the helicity amplitudes are used to compute the branch…
Re-analysis of rare radiative $Ξ_b^-\rightarrow Ξ^- γ$ decay in QCD
本文利用光锥QCD求和规则和 $Ξ_b$ 分布振幅重新分析稀有衰变 $Ξ_b^-\rightarrow Ξ^- γ$，得到分支比 $(4.8\pm1.3)\times10^{-5}$，低于LHCb实验上限，并与其他理论结果进行了比较。
In this work, we study the branching ratios of B^{0}_{s}\rightarrow a_{0}(980)[ \rightarrow K\overline{K}, πη]a_{0}(980), B^{0}_{s} \rightarrow f_{0}(980)[ \rightarrow π^{+}π^{-}, K^{+}K^{-}]f_{0}(980) and B^{0}_{s} \rightarrow f_{0}(500)[ \rightarrow π^{+}π^{-}]f_{0}(500) decays in the pQCD approach, in which the scalar mesons a_{0}(980), f_{0}(980) and f_{0}(500) are regarded as the lowest-lying q\overline{q} state. In the SU(3) nonet, there exists a mixing between the scalars f_{0}(980) and f_{0}(500), so we have considered the mixing effect in our calculations to obtain more reliable data,…
The widths of the strong decays $Z_c^{+}(3900)\to J/ψπ^{+}$ and $Z_c^{+}(3900)\to η_{c} ρ^{+}$ are calculated. To this end, the mass and decay constant of the exotic $Z_c^{+}(3900)$ state are computed by means of a two-point sum rule. The obtained results are then used to calculate the strong couplings $g_{Z_{c}J/ψπ}$ and $g_{Z_{c}η_{c} ρ}$ employing QCD sum rules on the light-cone supplied by a technique of the soft-meson approximation. We compare our predictions on the mass and decay widths with available experimental data and other theoretical results.
In this work, we study the localized $CP$ violation in $B^-\rightarrow K^-π^+π^-$ and $B^-\rightarrow K^- σ(600)$ decays by employing the quasi two-body QCD factorization approach. Both the resonance and the nonresonance contributions are studied for the $B^-\rightarrow K^-π^+π^-$ decay. The resonance contributions include those not only from $[ππ]$ channels including $σ(600)$, $ρ^0(770)$ and $ω(782)$ but also from $[Kπ]$ channels including $K^*(892)$, $K_0^*(1430)$, $K^*(1410)$, $K^*(1680)$ and $K_2^*(1430)$. By fitting the experimental data $\mathcal{A_{CP}}(K^-π^+π^-)=0.678\pm0.078\pm0.0323…
In this note, we study the contributions from the S-wave resonances, f_{0}(980) and f_{0}(1500), to the B^{0}_{s}\rightarrow ψ(3770)π^ {+}π^{-} decay by introducing the S-wave ππdistribution amplitudes within the framework of the perturbative QCD approach. Both resonant and nonresonant contributions are contained in the scalar form factor in the S-wave distribution amplitude Φ^S_{ππ}. Since the vector charmonium meson ψ(3770) is a S-D wave mixed state, we calculated the branching ratios of S-wave and D-wave respectively, and the results indicate that f_{0}(980) is the main contribution of the …
Perturbative QCD Fragmentation Functions for $B_c$ and $B_c^*$ Production
在高能过程中，${\bar b} c$束缚态的主要产生机制是产生高能${\bar b}$或$c$夸克，然后将其碎裂成${\bar b} c$态。我们计算了S波态$B_c$和$B_c^*$产生到QCD耦合常数首阶的碎裂函数。${\bar b} \rightarrow B_c$和${\bar b} \rightarrow B_c^*$的断裂概率约为$2.2 \times 10^{-4}$和$3.1 \times 10^{-4}$，而$c \rightarrow B_c$和$c \rightarrow B_c^*$的断裂概率小了几乎两个数量级。
We present a discussion of radiative decays $χ_{cJ}\rightarrowγρ(ω, ϕ)$. The decay amplitudes are computed within the QCD factorisation framework. NRQCD has been used in the heavy meson sector as well as a collinear expansion in order to describe the overlap with light mesons in the final state. The colour-singlet contributions to all helicity amplitudes have been computed using the light-cone distribution amplitudes of twist-2 and twist-3. All obtained expressions are well defined at least in the leading-order approximation. The colour-octet contributions have also been studied in the Coulomb…
We present analytical results for higher order corrections to the decay spectra of inclusive semileptonic heavy hadron weak decays using the heavy quark expansion (HQE). We compute analytically the spectrum of the leptonic invariant mass for $B \rightarrow X_c \ell \barν$ up to and including terms of order $1/m_Q^3$ within the HQE at next-to-leading order (NLO) in $α_s$. The full dependence of the differential rate on the mass of the final-state quark is taken into account. We discuss the implications of our results for the precision determination of the CKM matrix element $|V_{cb}|$.
We study the rare decay $Z_H \rightarrow H^0 γ$ at $\mathcal{O}(α_{\rm ew}^{3}α_s)$ accuracy including two-loop QCD corrections in the context of the littlest Higgs model (LHM) without $T$-parity. We revisit analytically and numerically the leading-order (LO) contributions of the one-loop diagrams induced by massive fermions, scalars and charged gauge bosons in the LHM, and further study the NLO QCD correction to this decay process. We perform the numerical calculation by taking the LHM input parameters $f=3,~4~\text{TeV}$ and $0.1< c <0.6$, and discuss the numerical results of the decay width…
The cross sections of $e^+e^- \rightarrow πZ_c(3900) \rightarrow ππJ/ψ$ and $e^+e^- \rightarrow πZ_c(3900) \rightarrow πD\bar{D}^{*}$ have been measured by BESIII experiment. We try to perform a combined fit to the cross sections with one Breit-Wigner function, the fit results show the structure's mass and width are $M=(4232\pm5)$ MeV/$c^2$, $Γ=(65\pm21)$ MeV. The ratio $\frac{\mathcal{B}(Z_c(3900)\rightarrow D\bar{D}^{*})}{\mathcal{B}(Z_c(3900)\rightarrowπJ/ψ)}$ is determined to be $(16\pm6)$. We also try to fit the cross sections with two Breit-Wigner functions, while we can't come to any de…
As one of the simplest hadronic processes, $γγ\rightarrow M^{+}M^{-}$ ($M=π,K$) could be a good testing ground for our understanding of the perturbative and nonperturbative structure of QCD, and will be studied with high precision at BELLE-\RNum{2} in the near future. In this paper, we revisit these processes with twist-3 corrections in the perturbative QCD approach based on the $k_{T}$ factorization theorem, in which transverse degrees of freedom as well as resummation effects are taken into account. The influence of the distribution amplitudes on the cross sections are discussed in detail. O…
We study the color-allowed $Λ_b\rightarrow Λ_c π, Λ_cK$ decays in the perturbative QCD approach (PQCD) to lowest order in strong coupling constant $α_s$. Both the factorizable and nonfactorizable contributions are taken into account in our calculations. It is found that these processes are dominated by the factorizable contributions, while the important nonfactorizable contributions can enhance the branching ratios by about 30$\%$. The decay branching ratios are predicted to be $\mathcal{B}(Λ_b\rightarrow Λ_c π)=6.7^{+4.1}_{-3.8}\times 10^{-3}$ and $\mathcal{B}(Λ_b\rightarrow Λ_c K)=5.0^{+4.0}…
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