Study of $Z$ bosons produced in association with charm in the forward region

TL;DR

This paper investigates the production of Z bosons with charm jets in the forward region of proton-proton collisions, revealing a potential intrinsic charm component in the proton's wave function.

Contribution

First measurement of Z boson and charm jet production in the forward region at 13 TeV, suggesting evidence for intrinsic charm in the proton.

Findings

Observed enhancement in charm jet fraction at high Z-boson rapidity

Indication of valence-like intrinsic charm component in the proton

Provides new insights into proton structure at high energies

Abstract

Events containing a $Z$ boson and a charm jet are studied for the first time in the forward region of proton-proton collisions. The data sample used corresponds to an integrated luminosity of $6 \, {\rm fb}^{-1}$ collected at a center-of-mass energy of 13 TeV with the LHCb detector. In events with a $Z$ boson and a jet, the fraction of charm jets is determined in intervals of $Z$-boson rapidity in the range $2.0 < y(Z) < 4.5$. A sizable enhancement is observed in the forward-most $y(Z)$ interval, which could be indicative of a valence-like intrinsic-charm component in the proton wave function.