Past exam of the particle physics course of the University of Oxford / 2018 / 2 / d / Solution

At $y=0$, both fractions equal $x=0.0402$. Reading the original plot near this value gives representative momentum densitiesThese are approximate graphical readings, not a precision PDF fit. Undo the sea-curve scale and divide by eight flavours/antiflavours:All products have the same $1/x^2$ factor, which cancels in the fractions. The three relative weights areTheir sum is $0.3128$, givingReading the central curves more finely changes these percentages by about a percentage point, well within what the plot supports. Omitting its factor $0.05$ would substantially underestimate the sea contribution.