PRODUCTION OF FORWARD CHARM AND NEUTRINOS, AND UNINTEGRATED GLUON DISTRIBUTIONS AT VERY SMALL x

In this presentation, we discussed production of charm quarks and anti-quarks, D mesons, and neutrinos/antineutrinos in forward and very forward directions. Gluon-gluon fusions, intrinsic charm, and recombination mechanisms were included. The gluon-gluon contribution, as well as the intrinsic charm contribution, were calculated in the k(t) and hybrid factorization, while the recombination contribution in the standard collinear approach. Different unintegrated gluon distributions from the literature were used. We compared the results of our calculations for D mesons with the LHCb data for different rapidity intervals. The best description was achieved for the Martin-Ryskin-Watt (MRW) uPDF. We presented also energy distributions for forward electron, muon, and tau neutrinos to be measured at the LHC by the currently operating FASER nu experiment, as well as by future experiments such as FASER nu 2 or FLArE, proposed very recently by the Forward Physics Facility project. At very forward directions, the intrinsic charm and recombination contributions become very important. We presented also neutrino energy fluxes including the above-mentioned processes. For electron and muon neutrinos, intrinsic charm and recombination mechanisms lead to similar production rates and their separation seems rather impossible. On the other hand, for nu(tau) + nu(tau) neutrino flux, the recombination is further reduced making the measurement of the IC contribution very attractive.