论文标题
质子上的抗蛋白质和k $^ - $^+k $^+$ $ $ $ $多数比在高$ z $ in dis中
Antiproton over proton and K$^-$ over K$^+$ multiplicity ratios at high $z$ in DIS
论文作者
论文摘要
$ \ bar {\ rm p} $超过p多样性比,首次使用(抗)质子携带的(抗)质子含有很大一部分的虚拟photon能量,$ z> 0.5 $。数据是通过指南针协作使用160 GEV MUON光束撞击Isoscalar $^6 $盖子目标的。通过需要$ q^2 $> 1(GEV/$ C $)$^2 $,用于光子虚拟的$ q^2 $> 1 $,以及$ W> 5 $ w> 5 $ GEV/$ C^2 $来确保深度无弹性散射的制度。 Bjorken- $ x $的范围限于$ 0.01 <x <0.40 $。在动量范围内确定质子和抗蛋白酶$ 20÷60 $ gev/$ c $。在整个研究的$ z $ - 区域中,发现$ \ bar {\ rm p} $超过p多重比的比率低于基于前阶扰动量子染色体动力学(PQCD)的计算所预期的下限。通过包括较大的虚拟光量能量的事件来扩展我们对K $^ - $的早期分析,超过K $^+$多数率的比率,该比率更接近对近代领先顺序PQCD的期望。两种分析的结果都加强了我们先前的结论,即在PQCD形式主义中应考虑可用于强扎的相位空间。
The $\bar{\rm p} $ over p multiplicity ratio is measured in deep-inelastic scattering for the first time using (anti-) protons carrying a large fraction of the virtual-photon energy, $z>0.5$. The data were obtained by the COMPASS Collaboration using a 160 GeV muon beam impinging on an isoscalar $^6$LiD target. The regime of deep-inelastic scattering is ensured by requiring $Q^2$ > 1 (GeV/$c$)$^2$ for the photon virtuality and $W > 5$ GeV/$c^2$ for the invariant mass of the produced hadronic system. The range in Bjorken-$x$ is restricted to $0.01 < x < 0.40$. Protons and antiprotons are identified in the momentum range $20 ÷60$ GeV/$c$. In the whole studied $z$-region, the $\bar{\rm p}$ over p multiplicity ratio is found to be below the lower limit expected from calculations based on leading-order perturbative Quantum Chromodynamics (pQCD). Extending our earlier analysis of the K$^-$ over K$^+$ multiplicity ratio by including now events with larger virtual-photon energies, this ratio becomes closer to the expectation of next-to-leading order pQCD. The results of both analyses strengthen our earlier conclusion that the phase space available for hadronisation should be taken into account in the pQCD formalism.