Small-$${p}_{{T}}$$ Production of $$\eta_{{c}}$$ Mesons within the Soft Gluon Resummation Approach

In this article we describe the $$\eta_{c}$$ production in proton–proton collisions at small values of the transverse momentum of the charmonium. Soft gluon resummation is used as a TMD factorization approach. At small transverse momenta, the color singlet contribution dominates, allowing us to use $$\eta_{c}$$ as a test of the resummation scheme for the noncollinear gluon PDF. The cross sections of $$\eta_{c}$$ production at $$\sqrt{s}=27$$ GeV, $$115$$ GeV and $$13$$ TeV are predicted.