## Abstract

The K^{−} over K^{+} multiplicity ratio is measured in deep-inelastic scattering, for the first time 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>5GeV/c^{2} for the invariant mass of the produced hadronic system. Kaons are identified in the momentum range from 12 GeV/c to 40 GeV/c, thereby restricting the range in Bjorken-x to 0.01<x<0.40. The z-dependence of the multiplicity ratio is studied for z>0.75. For very large values of z, i.e. z>0.8, we observe the kaon multiplicity ratio to fall below the lower limits expected from calculations based on leading and next-to-leading order perturbative quantum chromodynamics. Also, the kaon multiplicity ratio shows a strong dependence on the missing mass of the single-kaon production process. This suggests that within the perturbative quantum chromodynamics formalism an additional correction may be required, which takes into account the phase space available for hadronisation.

Original language | English |
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Pages (from-to) | 390-398 |

Number of pages | 9 |

Journal | Physics Letters B |

Volume | 786 |

DOIs | |

State | Published - 10 Nov 2018 |

Externally published | Yes |

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