Abstract
Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar 6 LiD target. They cover the kinematic domain 1 (GeV/c)2 < Q2 < 60 (GeV/c)^2 in the photon virtuality, 0.004 < x < 0.4, 0.1 < y < 0.7, 0.20 < z < 0.85, and W > 5 GeV/c^2 in the invariant mass of the hadronic system. The results from the sum of the z-integrated K+ and K- multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit.
Highlights
The study of strangeness in the nucleon has been arousing constant interest over the last decades, but the data sensitive to strangeness are still rather scarce
In this Letter, we present COMPASS results on differential multiplicities for charged kaons, which are derived from data taken simultaneously to those used for the determination of the differential multiplicities for charged pions [15]
A maximum uncertainty of 4% on the acceptance correction is derived from the following studies: varying the parton distribution functions (PDFs) set used, varying the JETSET parameters, using a fourdimensional space (x, y, z, pT ) with the hadron transverse momentum pT as fourth variable, varying the detector efficiency applied in the Monte Carlo (MC) simulation used for the acceptance calculation, as well as comparing multiplicity results from upstream and downstream target regions
Summary
The study of strangeness in the nucleon has been arousing constant interest over the last decades, but the data sensitive to strangeness are still rather scarce. The values of s(x) extracted using only semi-inclusive DIS measurements (hereafter referred to as SIDIS) of identified kaons using polarised beam and target are found to be compatible with zero in the measured kinematic range [5,6,7]. The latter evaluations require knowledge of the collinear quark fragmentation functions (FFs), in particular knowledge of the quark-to-kaon FF.
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