Kaon Multiplicities of Semi-inclusive DIS and the Fragmentation Functions

There is an apparent discrepancy between the results of the charged kaon multiplicities off the deuteron target from HERMES and COMPASS experiments. In this article we point out that this discrepancy cannot be explained by different $Q^2$ values. Furthermore we examine the empirical parametrization of the fragmentation functions, DSS2017 carefully and find that the agreement between the theoretical estimate and the HERMES data is less satisfactory as claimed.