On transverse single-spin asymmetries in $D$-meson production at the SPD NICA experiment

In the present study we are interested in the Sivers effect in process $p^{\uparrow }p\to DX$. We calculate the transverse single-spin asymmetry (TSSA) of $D$-meson production within two phenomenological models, namely the Generalized Parton Model (GPM) and it’s Colour Gauge-Invariant formulation (CGI-GPM), which takes into account the transverse momenta of initial partons. The last one allows us to study process-independent Sivers functions. To predict production cross-section of $D$-mesons we use a fragmentation approach with scale-independent Peterson fragmentation function, taking in mind nonzero masses of $c$-quark and $D$-mesons. Estimates for the TSSAs, as a function of transverse momentum and Feynman variable $x_F$ of $D$-meson, within the conditions of the planned SPD NICA experiment are presented for the first time.