Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV

TL;DR

This study measures the electron yields from bottom and charm quark decays in proton-proton collisions at 200 GeV, finding bottom contributions become significant above 4 GeV/c and aligning with pQCD predictions.

Contribution

It provides the first detailed measurement of bottom versus charm electron yields as a function of transverse momentum in p+p collisions at RHIC energies.

Findings

Electrons from bottom decay dominate above 4 GeV/c.

The measured bottom production cross section agrees with pQCD calculations.

The ratio of bottom to charm electrons increases with p_T.

Abstract

The momentum distribution of electrons from semi-leptonic decays of charm and bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative quantum chromodynamics (pQCD) calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is \sigma_{b\b^bar}= 3.2 ^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.