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arXiv 0901.0228hep-ph
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一个扩展的九态赝标介子碎裂模型

An extended model for nonet pseudo-scalar meson fragmentation

D. Indumathi, Basudha Misra

摘要:

为了研究八重态介子(π,K)的碎裂函数,在合理的假设下,将一个具有较高预测性的SU(3)对称模型推广到单重态,并对SU(3)对称破缺(由于相对重的奇夸克)进行了简单的处理.由于SU(3)对称性的存在,对π和K数据的拟合有助于约束η和η'介子的碎裂函数。在e^+e^-碰撞中使用包含2喷注和3喷注(特别是胶子喷注)的介子产生,在pp碰撞中使用包含π和η的介子产生,也使得胶子碎裂函数的提取成为可能。当奇异介子(K^{+-},K^0,Kbar ^0)和较重的η,η'介子中的海夸克受到λ_H = m_π^2/m_H^2 < 0.1(H=K,η,η')因子的抑制时,胶子没有受到那么严重的抑制:f_g^H=0.3- 0.35。本文给出了LO QCD中三个独立碎裂函数V(x,Q2),γ(x,Q2)和D_g(x,Q2)的详细参数化,所有九态介子胶子碎裂函数和各种味的夸克碎裂函数都可以用这些函数表示,只需要包括λ_H和f_g在内的几个模型参数。结果表明,混合角为-24度<=θ_P<=-16度,排除了无混合的可能。

英文摘要:

An SU(3) symmetric model with high predictivity for octet meson (π, K) quark fragmentation functions with a simple approach to SU(3) symmetry breaking (due to the relatively heavy strange quarks) is extended to the singlet sector, with some reasonable assumptions, in order to study ηand η' fragmentation. Due to the presence of SU(3) symmetry, fits to the πand K data help to constrain the fragmentation functions for ηand η' mesons. The use of 2-jet and 3-jet (especially the gluon jet) inclusive meson production in e^+e^- collisions and π, ηinclusive production in p p collisions enable the extraction of the gluon fragmentation functions as well. While sea quarks in strange mesons (K^{+-},K^0,Kbar^0) and the heavier η, η' mesons are suppressed by a factor of lambda_H = m_π^2/m_H^2 < 0.1 for H=K,η,η', the gluons are not as severely suppressed: f_g^H=0.3--0.35. A detailed parametrisation of the three independent fragmentation functions V(x, Q2), γ(x, Q2), and D_g(x, Q2) are given in LO QCD; all nonet meson gluon fragmentation functions and quark fragmentation functions of all flavours can be expressed in terms of these functions with a few model parameters including λ_H and f_g. The data prefer a nonet mixing angle -24deg<=θ_P<=-16deg and rule out no-mixing.

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