IC at IC: IceCube can constrain the intrinsic charm of the proton

Understand

The discovery of extraterrestrial neutrinos in the $\sim$ 30 TeV -- PeV energy range by IceCube provides new constraints on high energy astrophysics.

• An important background to the signal are the prompt neutrinos which originate from the decay of charm hadrons produced by high energy cosmic-ray particles interacting in the Earth's atmosphere.
• It is conventional to use the calculations of charm hadroproduction using gluon splitting $g \to c \bar c$ alone.
• However, QCD predicts an additional "intrinsic" component of the heavy quark distribution which arises from diagrams where heavy quarks are multiply connected to the proton's valence quarks.