$Z$ boson production in bottom-quark fusion: a study of $b$-mass effects beyond leading order

TL;DR

This paper calculates the total cross-section for Z boson production via bottom-quark fusion, combining massless and massive quark schemes to improve accuracy and address heavy quark treatment issues.

Contribution

It introduces a matched calculation using FONLL for Z production in bottom fusion, extending previous methods applied to Higgs production to this process.

Findings

The matched scheme reduces scale dependence.

Mass effects are significant at certain energies.

Results improve theoretical predictions for Z production.

Abstract

We compute the total cross-section for $Z$ boson production in bottom-quark fusion, applying to this case the method we previously used for Higgs production in bottom fusion. Namely, we match, through the FONLL procedure, the next-to-next-to-leading-log five-flavor scheme result, in which the $b$~quark is treated as a massless parton, with the next-to-leading-order $\order{\alpha_s^3}$ four-flavor scheme computation in which bottom is treated as a massive final-state particle. Our computation provides a test-case for the discussion of issues of scale dependence and treatment of heavy quarks, which we discuss in light of our results.