Cross sections of η mesons in p + p collisions at forward rapidity at s = 500 GeV and central rapidity at s = 510 GeV

We present the first measurements of the forward and midrapidity η -meson cross sections from p + p collisions at s = 500 and 510 GeV, respectively. We also report the midrapidity η / π 0 ratio at 510 GeV. The forward cross section is measured differentially in η -meson transverse momentum ( p T ) from 1.0 to 6.5 GeV / c for pseudorapidity 3.0 < | η | < 3.8 . The midrapidity cross section is measured from 3.5 to 44 GeV / c for pseudorapidity | η | < 0.35 . Both cross sections serve as critical inputs to an updated global analysis of the η -meson fragmentation functions.