What’s interesting is that there’s a net charm content: there are more charm quarks to be found than anti-charms. Given that charm quarks are heavier than the

What’s interesting is that there’s a net charm content: there are more charm quarks to be found than anti-charms. Given that charm quarks are heavier than the proton, you’d expect to only find them in deep inelastic collisions when they are produced in pairs with an anti-quark, so it is surprising that there’s an asymmetry.