Constraints on atmospheric charmed-meson production from IceCube

At very-high energies (100 TeV - 1 PeV), the small value of Bjorken-x (≤ 10⁻³ − 10⁻⁷) at which the parton distribution functions are evaluated makes the calculation of charm quark production very difficult. The charm quark has mass (~1.5±0.2 GeV) significantly above the ΛQCD scale (~200 MeV), and therefore its production is perturbatively calculable. However, the uncertainty in the data and the calculations cannot exclude some smaller non-perturbative contribution. To evaluate the prompt neutrino flux, one needs to know the charm production cross-section in pN -> cc̄ X, and hadronization of charm particles. This contribution briefly discusses computation of prompt neutrino flux and presents the strongest limit on prompt neutrino flux from IceCube.