COMPASS collaboration (210 authors)Bordalo, PFranco, CNunes, A SQuaresma, MQuintans, CRamos, SSilva, LStolarski, M2019-02-042019-02-042016-02-10http://dx.doi.org/10.1016/j.physletb.2015.12.035http://hdl.handle.net/10400.26/26922We measured the longitudinal double spin asymmetries $A_{LL}$ for single hadron muo-production off protons and deuterons at photon virtuality $Q^2$ < 1(GeV/$\it c$)$^2$ for transverse hadron momenta $p_T$ in the range 0.7 GeV/$\it c$ to 4 GeV/$\it c$ . They were determined using COMPASS data taken with a polarised muon beam of 160 GeV/$\it c$ or 200 GeV/$\it c$ impinging on polarised $\mathrm{{}^6LiD}$ or $\mathrm{NH_3}$ targets. The experimental asymmetries are compared to next-to-leading order pQCD calculations, and are sensitive to the gluon polarisation $\Delta G$ inside the nucleon in the range of the nucleon momentum fraction carried by gluons $0.05 < x_g < 0.2$.engjournal article2019-02-04