Measurement of the ratio of the $p\bar{p}\to W$+$c$-jet cross section to the inclusive $p\bar{p}\to W$+jets cross section

TL;DR

This paper measures the ratio of $W$+charm-jet events to all $W$+jets events in proton-antiproton collisions, providing insights into charm production in high-energy physics.

Contribution

It introduces a nearly model-independent method to identify $W$+$c$-jet events using muon charge correlation, and measures their fraction with statistical significance.

Findings

Measured $W$+$c$-jet fraction as 0.074±0.019 (stat.)±0.012-0.014 (syst.)

Results agree with theoretical predictions

Observed a 3.5 sigma significance for the $W$+$c$-jet signal

Abstract

We present a measurement of the fraction of inclusive $W$+jets events produced with net charm quantum number $\pm1$, denoted $W$+$c$-jet, in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using approximately 1~fb$^{-1}$ of data collected by the D0 detector at the Fermilab Tevatron Collider. We identify the $W$+jets events via the leptonic $W$ boson decays. Candidate $W$+$c$-jet events are selected by requiring a jet containing a muon in association with a reconstructed $W$ boson and exploiting the charge correlation between this muon and $W$ boson decay lepton to perform a nearly model-independent background subtraction. We measure the fraction of $W$+$c$-jet events in the inclusive $W$+jets sample for jet $p_{T}>20$ GeV and pseudorapidity $|\eta|<2.5$ to be 0.074$\pm0.019$(stat.)$\pm^{0.012}_{0.014}$(syst.), in agreement with theoretical predictions. The probability that background fluctuations could produce the observed fraction of $W$+$c$-jet events is estimated to be $2.5\times 10^{-4}$, which corresponds to a 3.5 $\sigma$ statistical significance.