Speaker
Description
The COMPASS experiment plays an important role in studies of nucleon structure. Measurements performed in 2016–2017 with an unpolarised liquid hydrogen target and a longitudinally polarised 160 GeV/$c$ muon beam provide a high-statistics data sample for the analysis of semi-inclusive deep-inelastic scattering, giving access to transverse-momentum-dependent parton distribution and fragmentation functions.
The 2016 data set was analysed to determine the multiplicities of hadrons produced in DIS differential in $x$, $Q^2$, $z$ and $P_\text{T}$, as well as the amplitudes of modulations in their azimuthal-angle distributions. In particular, the unpolarised asymmetries $A^{\cos \phi_\text{h}}_\text{UU}$ (related to the Cahn effect), $A^{\cos 2\phi_\text{h}}_\text{UU}$ (sensitive to the Boer–Mulders function), and the beam-spin asymmetry $A^{\sin \phi_\text{h}}_\text{LU}$ were extracted in 4-dimensional bins matching those of the multiplicities, and also integrated over some of the variables.
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