Cross sections of $\eta$ mesons in $p$$+$$p$ collisions at forward rapidity at $\sqrt{s}=500$ GeV and central rapidity at $\sqrt{s}=510$ GeV

TL;DR

This paper reports the first measurements of $ ext{eta}$-meson production cross sections at forward and central rapidities in proton-proton collisions at $ ext{sqrt(s)}=500$ and 510 GeV, providing essential data for understanding meson fragmentation.

Contribution

It provides the first experimental cross section data for $ ext{eta}$ mesons at these energies and rapidities, improving global fragmentation function analyses.

Findings

Forward $ ext{eta}$ cross section measured from 1.0 to 6.5 GeV/c in $p_T$

Midrapidity $ ext{eta}$ cross section measured from 3.5 to 44 GeV/c

Midrapidity $ ext{eta}/ ext{pi}^0$ ratio reported at 510 GeV

Abstract

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