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Antiproton over proton and K\(^-\) over K\(^+\) multiplicity ratios at high \(z\) in DIS
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 isoscal...
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Published in: | arXiv.org 2020-03 |
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Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
Format: | Article |
Language: | English |
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Online Access: | Get full text |
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Summary: | 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 \(20 \div 60\) 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. |
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ISSN: | 2331-8422 |
DOI: | 10.48550/arxiv.2003.11791 |