Measurement of F_2^{c\bar{c}} and F_2^{b\bar{b}} at Low Q^2 and x using the H1 Vertex Detector at HERA

TL;DR

This paper reports the first measurement of the beauty structure function F_2^{bar{b}} at low Q^2 and x in e^+p collisions at HERA, using impact parameter techniques with the H1 vertex detector, confirming QCD predictions.

Contribution

It introduces a novel method based on impact parameter measurements to determine charm and beauty fractions, providing the first F_2^{bar{b}} data in this kinematic range.

Findings

F_2^{bar{b}} measured for the first time at low Q^2 and x

Results agree with perturbative QCD predictions

Compatibility with previous F_2^{car{c}} measurements

Abstract

Measurements are presented of inclusive charm and beauty cross sections in e^+p collisions at HERA for values of photon virtuality 12 \le Q^2 \le 60 GeV^2 and of the Bjorken scaling variable 0.0002 \le x \le 0.005. The fractions of events containing charm and beauty quarks are determined using a method based on the impact parameter, in the transverse plane, of tracks to the primary vertex, as measured by the H1 vertex detector. Values for the structure functions F_2^{c\bar{c}} and F_2^{b\bar{b}} are obtained. This is the first measurement of F_2^{b\bar{b}} in this kinematic range. The results are found to be compatible with the predictions of perturbative quantum chromodynamics and withprevious measurements of F_2^{c\bar{c}}.