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arXiv 1003.2127hep-phhep-exnucl-ex
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e+e-,强子和核碰撞中的软粒子发射极限

Limiting soft particle emission in e+e-, hadronic and nuclear collisions

Wolfgang Ochs, Valery A. Khoze, M. G. Ryskin

摘要:

在e+e碰撞中,低动量粒子谱反映了QCD胶子韧致辐射的基本性质:粒子密度在pPDMATHABMM 0的极限下与入射能量\sqrt{s}无关,而分别与原胶子或夸克的色因子C_A、C_F成正比。我们发现pp和核反应的实验数据揭示了相同的行为:在p_T \to 0极限下,不变粒子谱变得与碰撞能量无关,并且它们在e+e-、pp和核反应中的强度与预期的颜色因子C_F:C_A兼容:(N_{part} /2)C_A对于参与相互作用的N_{part}核子。因此,在所有这些反应中,软胶子韧致辐射被认为是软粒子产生的主要QCD机制。这些“软”粒子探测碰撞中强子形成的非常早期阶段。LHC未来的测量将对可能的非相干多组分过程的贡献提供关键的测试。

英文摘要:

In e+e- collisions the particle spectra at low momenta reflect the properties of the underlying "soft" QCD gluon bremsstrahlung: the particle density, in the limit p\to 0, becomes independent of the incoming energy \sqrt{s} and directly proportional to the colour factors C_A,C_F for primary gluons or quarks respectively. We find that experimental data from the pp and nuclear reactions reveal the same behaviour: in the limit p_T\to 0 the invariant particle spectra become independent of the collision energy, and their intensities in e+e-, pp and nuclear reactions are compatible with the expected colour factors C_F: C_A: (N_{part}/2) C_A for N_{part} nucleons, participating in the interaction. Coherent soft gluon bremsstrahlung is, therefore, suggested to be the dominant QCD mechanism for the soft particle production in all these reactions. These "soft" particles probe the very early stage of hadron formation in the collision. Future measurements at the LHC will provide crucial tests on the contributions from possible incoherent multi-component processes.

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