Heavy Quark Contributions

These kind of contributions account for all those cases in which there is at least one massive quark, but not in the input state (for these ones see Heavy-Initiated Contributions (Intrinsic)).

Two masses contributions are never accounted for, so it is only considered the case in which all massive fermion lines belong to the same flavor (lighter ones are considered massless, while heavier are considered infinitely massive).

There is always a kinematic cut included in the case of massive corrections, due to the need to generate the massive quark

• in the case of NC is applied as a cut:

  \[Q^2 \frac{1-z}{z} > 4 m_h^2\]

• in the case of CC is applied modifying the convolution point

Asymptotic

They stem from the heavy contributions, and they are the actual asymptotic limit for very large \(Q^2\).

Only logarithmic terms are retained, while all the power contributions are removed (thus the asymptotic limit can be null).

They are needed to construct the FONLL scheme.