The decays of pseudoscalar bottomonium eta_b into a pair of vector charmonia, J/ψJ/ψ, J/ψψ', ψ' ψ' are considered in the light cone formalism. Relativistic and leading logarithmic radiative corrections to the amplitudes of these processes are resummed. It is shown that the small value for the branching ratio of the decay eta_b-> J/ψJ/ψobtained within the leading order nonrelativistic QCD is a consequence of a fine-tuning between certain parameters, which is broken when relativistic and leading logarithmic radiative corrections are taken into account. As a result, the branching ratio obtained in this paper is enhanced by an order of magnitude.
B->pi,K,eta Decay Formfactors from Light-Cone Sum Rules
我们提出了一种改进的计算所有B ->轻赝标形状因子的光锥求和规则，包括单圈辐射校正扭曲-2和扭曲-3的贡献，和领先的订单扭曲-4校正。在零动量转移时，我们的结果的总理论不确定性为10%至13%。形状因子对动量传递q^2的依赖关系可以用一种简单的方法进行参数化，这种方法与它们的分析性质一致，并且对所有物理量q^2都有效。在q^2中外推半轻子衰变率γ（B -> pie nu）的不确定性估计为5%。
Reconciling the light-cone and nonrelativistic QCD approaches to calculating e+ e- -> J/psi + eta_c
在参考文献[A]中已经提出了这一点。E. Bondar和V.L. Chernyak，Phys. Lett. B612，215（2005）]认为，在B工厂中e+ e- -> J/psi + eta_c过程速率的理论计算和实验观测之间的不一致，可以通过使用光锥方法来解决，以考虑夸克偶素中重夸克和反夸克的相对动量。参考文献[A]中的生产截面的光锥结果。E. Bondar和V.L. Chernyak，Phys. Lett. B 612，215（2005）]比现有的NRQCD因式分解结果几乎大一个数量级。我们调查这个明显的理论矛盾。我们利用Cornell势模型中的夸克偶素波函数计算光锥分布函数。我们的光锥分布函数在形状上与参考文献[A]的相似。E. Bondar和V.L. Chernyak，Phys. Lett. B 612，215（2005）]并产生类似的截面。然而，当我们减去NRQCD方法中对应于相对阶α_s修正的部分光锥分布函数时，我们发现截面减小了约三倍。当我们在光锥计算中将某些重整化因子Z_i设为1时，我们发现截面进一步减小约为1/2。由此得到的光锥截面与NRQCD因子分解截面的大小相似，并且在忽略重夸克和反夸克的相对动量的光锥截面上只显示出适度的增强。
In the framework of the QCD light-cone sum rules (LCSRs) we present the analysis of all $B, B_{s}\to η^{(\prime)}$ and $D, D_{s}\to η^{(\prime)}$ form factors ($f^+, f^0$ and $f^T$) by including $m_{η^{(\prime)}}^2$ corrections in the leading (up to the twist-four) and next-to-leading order (up to the twist-three) in QCD, and two-gluon contributions to the form factors at the leading twist. The SU(3)-flavour breaking corrections and the axial anomaly contributions to the distribution amplitudes are also consistently taken into account. The complete results for the $f^0$ and $f^T$ form factors …
In this paper the cross sections of the processes $e^+ e^- \to H+γ, H=η_c, η_c', χ_{c0}, χ_{c1}, χ_{c2}$ are calculated. The calculation is carried out at the leading twist approximation of light cone formalism. Within this approach the leading logarithmic radiative and relativistic corrections to the amplitudes are resumed. For the processes $e^+ e^- \to η_c, η_c'+γ$ one loop radiative corrections are taken into account. It is also shown that one loop leading logarithmic radiative corrections calculated within light cone formalism for the processes under study coincide with that obtained by d…
The process $\epem\to J/ ψX(3940)$ at $\sqrt s = 10.6$ GeV in the framework of light cone formalism
本文在光锥形式主义的框架下研究过程$\epem\to J/ψX(3940)$。计算中考虑了X（3940）介子的两种结构假设：X（3940）是$3^1$ S $_0$态和X（3940）是$2^3$ P态之一。前一个假设与实验测量的截面非常一致。对于后者，提出了一种机制，使人们能够理解在硬过程中的2P介子产生的抑制。
We compute one-loop renormalization group equations for non-singlet twist-four operators in QCD. The calculation heavily relies on the light-cone gauge formalism in the momentum fraction space that essentially rephrases the analysis of all two-to two and two-to-three transition kernels to purely algebraic manipulations both for non- and quasipartonic operators. This is the first brute force calculation of this sector available in the literature. Fourier transforming our findings to the coordinate space, we checked them against available results obtained within a conformal symmetry-based formal…
Kaon Electromagnetic Form Factor within the $k_T$ Factorization Formalism and It's Light-Cone Wave Function
本文在$k_T$分解的基础上，系统地研究了K介子的电磁形状因子$F_{K^{\pm},K^0,\bar{K}^0}(Q^2)$，详细分析了横向动量效应、K介子光锥波函数的不同螺旋度分量和不同扭曲结构对电磁形状因子$F_{K^{\pm},K^0,\bar{K}^0}(Q^2)$的贡献，以便更好地理解在pQCD适用的能区的硬贡献.通过保持硬振幅中的$k_T$依赖性，可以获得来自较高螺旋度分量和来自较高扭转结构的硬贡献的正确幂次行为。结果表明，LC波函数中的$k_T$依赖性对硬、软贡献有很大影响，而幂次抑制项（扭曲度3和更高螺旋度分量）在低于$Q^2\sim several GeV^2$时有重要贡献，但随着$k_T$的增加，它们下降得很快.所提出的模型波函数的参数可以通过其分布振幅的前两阶矩等条件来确定。通过改变前两阶矩$a^K_1(1GeV)$和$a^K_2(1GeV)$分别与$0.05\pm0.02$和$0.10\pm 0.05$的区域，我们发现，K介子电磁形状因子的不确定性是相当小的。
I review the resummation formalism for organizing large logarithms in perturbative expansion of collinear subprocesses through the variation of Wilson lines off the light cone. A master equation is derived, which involves the evolution kernel resulting from this variation. It is then demonstrated that all the known single- and double-logarithm summations for a parton distribution function or a transverse-momentum-dependentparton distribution can be reproduced from the master equation by applying appropriate soft-gluon approximations to the evolution kernel. Moreover, jet substructures, informa…
We revisit the problem of quark production in high energy heavy ion collisions, at leading order in $α_s$ in the color glass condensate framework. In this first paper, we setup the formalism and express the quark spectrum in terms of a set of mode functions of the Dirac equation. We determine analytically their initial value in the Fock-Schwinger gauge on a proper time surface $Q_sτ_0\ll 1$, in a basis which makes manifest the boost invariance properties of this problem. We also describe a statistical algorithm to perform the sampling of the mode functions.
We discuss the general formalism for the calculation in light-cone quark models of the fully unintegrated, off-diagonal quark-quark correlator of the nucleon. The corresponding distributions in impact parameter space are the Wigner or phase-space distributions. The results obtained in two different light-cone quark models in the case of unpolarized quarks in an unpolarized proton are very similar and present a non-trivial shape which can be understood as due to the orbital motion of the quarks.
This work studies the experiments of two-photon processes at BESIII from a theoretical viewpoint in light-cone quantum field theory. We adopt the momentum space wave function of the pion in the light-cone formalism by two forms of the Brodsky-Huang-Lepage~(BHL) prescription and the light-cone holographic QCD. We find that the wave function got by the light-cone holographic QCD can be related to the BHL wave function by a Jacobian factor. Then we calculate the transition form factor~(TFF) of the two-photon process by these two wave functions under the light-cone quark model. We compare the calc…
The deuteron is considered as a superposition of two-nucleon Fock states with the invariant mass depending on the relative momentum in a proton-neutron pair. The condition of the transversality of the polarization vectors should be imposed at the Fock component level and these vectors depend on the invariant mass of the Fock component. Such "running" longitudinal polarization vector was not used in early estimates of relativistic effects. The technique for the calculation of the average helicity of the proton in the deuteron has been considered in the light-cone variables. A receipt has been p…
We outline a novel approach to develop an in-medium shower Monte-Carlo event generator based on the higher-twist formalism of jet modification. By undoing one of the light-cone integrals which sets the corresponding light-cone momentum to be equal in the amplitude and the complex conjugate, we introduce an uncertainty in the smaller light-cone momentum component. This allows for the generalization of the standard analytic formalism to a Wigner transform like formalism, where the non-conjugate large light-cone momentum and position are retained for each parton. Jets are generated event-by-event…
Baryon Light-Cone Distribution Amplitudes from Lattice QCD: Formalism, Renormalization, Extrapolation, and Matching
Shanghai Jiao Tong University（上海交通大学）；Institute of High Energy Physics, CAS（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Adam Mickiewicz University（亚当·密茨凯维奇大学）；South China Normal University（华南师范大学）
We discuss the spin structure of the proton in a light-cone treatment of the chiral quark model. Based on the fact that the quark helicity ($Δq$) measured in polarized deep inelastic scattering experiments is actually the quark spin defined in the light-cone formalism, rather than the quark spin ($Δq_{QM}$) defined in the conventionally quark model (or in the rest frame of the nucleon), we calculate the $x$-dependence of the polarized quark distribution functions $Δq(x)$, and the polarized structure functions $g_1 (x)$. Special attention is focused on the Melosh-Wigner rotation due to the tran…
Semileptonic decay processes of $Ξ_c \to Ξ\ellν_\ell$ are studied by light-cone QCD sum rules in this paper. The six form factors of $Ξ_c \to Ξ$ semileptonic transition matrix elements are calculated by this method with the light-cone distribution amplitudes of $Ξ$ baryon up to twist six. With the six form factors, the absolute branching ratios of $Ξ_c^0 \to Ξ^- \ell^+ ν_\ell$ and $Ξ_c^+ \to Ξ^0 \ell^+ ν_\ell$ are calculated by the helicity amplitudes formalism of semileptonic differential decay widths. The ratios of absolute branching ratios of electron and muon final states processes give th…
这是光锥场论中真空问题的概述，强调了它与光锥量子化的其他难题的密切联系。我解释了光锥真空是“平凡的”的意义，并描述了一种在零平面上建立量子场论的方法，使它等价于通常的等时公式。这种结构对于解决光锥形式主义的令人困惑的方面非常有帮助。它还允许提取有效的哈密顿量，包括真空物理，但在希尔伯特空间中的真空状态是简单的。讨论相当非正式，主要集中在概念问题上。[Talk在{ \sc Orbis Scientiae 1996}，Miami Beach，FL，1996年1月25- 28日提出。在诉讼程序中出现]。
