K± Production in Semi-Inclusive Deep Inelastic Scattering Using Transversely Polarized Targets and the SoLID Spectrometer

We propose to perform the measurement of theK± production in the Semi-Inclusive Deep Inelastic Scattering (SIDIS) using both the transversely polarized proton (NH3) target and the transversely polarized He target (as effective polarized neutron target) on the SoLID spectrometer. This measurement will be carried out in parallel with the already approved SoLID experiments which will measure the π± production in SIDIS, including E12-10-006 with a transversely polarized He target and E12-11-108 with a transversely polarized NH3 target. We will perform the off-line analysis to extract the K ± Collins asymmetries, Sivers asymmetries and other TMD asymmetries. Model estimation shows that at the SoLID kinematic about 20% of the kaon SIDIS events come from the current fragmentation region where the TMD factorization can be applied. New data from this measurement will provide not only important input to determine the TMD of u and d valence-quarks by combining with the pion measurements from SoLID and elsewhere, but also has the unique sensitivity to sea-quarks, e.g. s and s̄. Our measurement will have a strong contribution to the development of the TMD physics and provide important guidance for studying sea-quarks and gluon TMDs on the future EIC. This run group proposal does not need additional beam-time nor requires modification to the existing experiment design. The heavy-gas Čerenkov detector and the MRPC in the standard SIDIS setup already have the capability of identifying kaons from pions and protons at certain momentum ranges. We hope to improve the MRPC’s time resolution down to 20 ps which should provide precise time-of-flight information for better π±/K± separation up to a high hadron momentum (e.g. Ph < 7.0 GeV/c). In this proposal, we will demonstrate that such a requirement is achievable in today’s detector technologies.