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Volume 316 - XXVI International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2018) - WG1: Structure Functions and Parton Densities
K- over K+ multiplicity ratio for kaons produced in DIS with a large fraction of the virtual-photon energy
A.S. Nunes* on behalf of the COMPASS Collaboration
*corresponding author
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Pre-published on: 2018 September 20
Published on: 2018 November 23
For the first time, the $K^-/K^+$ multiplicity ratio is measured in deep-inelastic scattering for kaons carrying a large fraction $z$ of the virtual-photon energy. The data were obtained by the COMPASS collaboration using a 160 GeV muon beam and 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 Bjorken scaling variable range is $0.01<x<0.40$. The $z$-dependence of the multiplicity ratio is studied for $z>0.75$. For very large values of $z$, {\it i.e.} $z>0.8$, the results contradict expectations obtained using the formalism of (next-to-)leading order perturbative quantum chromodynamics. Our studies suggest that, within this formalism, an additional correction may be required to take into account the phase space available for hadronisation.
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