Flavor, transverse momentum, and azimuthal dependence of charged pion multiplicities in semi-inclusive deep-inelastic scattering with 10.6 GeV electrons
Measurements of semi-inclusive deep-inelastic scattering multiplicities for π + and π β from proton and deuteron targets are reported on a grid of hadron kinematic variables π§, π π , and π* for leptonic kinematic variables in the range 0.3<π₯<0.6 and 3<π 2 <5GeV 2 . Data were acquired in 2018 and 2019 at Jefferson Lab Hall C with a 10.6 GeV electron beam impinging on 10-cm-long liquid hydrogen and deuterium targets. Scattered electrons and charged pions were detected in the High Momentum Spectrometer and Super High Momentum Spectrometer, respectively. The multiplicities were fitted for each bin in (π₯,π 2 ,π§,ππ‘) to extract the π*βindependent π 0 and the azimuthal modulations β¨cosβ‘(π*)β© and β¨cosβ‘(2β’π*)β©. The ππ‘ dependence of the π 0 results was found to be remarkably consistent for the four cases studied: πβ’πβπβ’π + β’π, πβ’πβπβ’π β β’π, πβ’πβπβ’π + β’π, πβ’πβπβ’π β β’π over the range 0GeV<π π‘ <0.4GeV, as were the multiplicities evaluated near π*=180β over the extended range 0GeV<π π‘ <0.7GeV. The Gaussian widths of the π π‘ dependence exhibit a quadratic increase with π§. The cosβ‘(π*) modulations were found to be consistent with zero for π + , in agreement with previous world data, while the π β moments were, in many cases, significantly greater than zero. The cosβ‘(2β’π*) modulations were found to be consistent with zero. The higher statistical precision of this dataset of about 20 000 individual multiplicity values, compared with previously published data, should allow improved determinations of quark transverse momentum distributions and higher twist contributions.