A Review of the Intrinsic Heavy Quark Content of the Nucleon

Figure 2

The global chi-square function versus charm momentum fraction . The two curves are determined from fits with many values of . Two exemplary fits for each IC model are shown as dots. Blue dots denote the BHPS model; the dots have and 2%, which are denoted as BHPS1 and BHPS2. Red denotes SEA model; the dots have and 1.5%, which are denoted as SEA1 and SEA2. Additionally the dotted lines show global chi-square function with additional penalty, , used to set the upper limits on the allowed IC component (figure taken from [42]).