Precise study of the Z/gamma* boson transverse momentum distribution in ppbar collisions using a novel technique

TL;DR

This paper introduces a novel technique to measure the Z/gamma* boson transverse momentum distribution using the extbackslash phi^* variable, providing insights into QCD effects with reduced experimental uncertainties.

Contribution

The study presents a new measurement method for boson transverse momentum distribution that minimizes experimental resolution effects, and compares it with QCD predictions highlighting discrepancies.

Findings

QCD predictions match general features but not detailed shape

Broadening of transverse momentum at small parton momentum fractions is disfavored

The extbackslash phi^* variable effectively probes boson kinematics with less experimental bias

Abstract

Using 7.3 pb-1 of ppbar collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable \phistar, which probes the same physical effects as the Z/gamma* boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the \phistar distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly disfavored.