On the Perturbative Stability of the QCD Predictions for the Ratio $R=F_L/F_T$ in Heavy-Quark Leptoproduction
| dc.creator | Ivanov, N. Ya. | |
| dc.creator | Kniehl, B. A. | |
| dc.date | 2008-06-30 | |
| dc.date | 2008-11-21 | |
| dc.date.accessioned | 2026-07-07T12:55:07Z | |
| dc.date.available | 2026-07-07T12:55:07Z | |
| dc.description | We analyze the perturbative and parametric stability of the QCD predictions for the Callan-Gross ratio $R(x,Q^2)=F_L/F_T$ in heavy-quark leptoproduction. We consider the radiative corrections to the dominant photon-gluon fusion mechanism. In various kinematic regions, the following contributions are investigated: exact NLO results at low and moderate $Q^2\lesssim m^2$, asymptotic NLO predictions at high $Q^2\gg m^2$, and both NLO and NNLO soft-gluon (or threshold) corrections at large Bjorken $x$. Our analysis shows that large radiative corrections to the structure functions $F_T(x,Q^2)$ and $F_L(x,Q^2)$ cancel each other in their ratio $R(x,Q^2)$ with good accuracy. As a result, the NLO contributions to the Callan-Gross ratio are less than 10% in a wide region of the variables $x$ and $Q^2$. We provide compact LO predictions for $R(x,Q^2)$ in the case of low $x\ll 1$. A simple formula connecting the high-energy behavior of the Callan-Gross ratio and low-$x$ asymptotics of the gluon density is derived. It is shown that the obtained hadron-level predictions for $R(x\to 0,Q^2)$ are stable under the DGLAP evolution of the gluon distribution function. Our analytic results simplify the extraction of the structure functions $F_2^c(x,Q^2)$ and $F_2^b(x,Q^2)$ from measurements of the corresponding reduced cross sections, in particular at DESY HERA. | |
| dc.description | 14 pages, 6 figures, revtex4; minor corrections | |
| dc.identifier | https://arxiv.org/abs/0806.4705 | |
| dc.identifier | http://arxiv.org/abs/0806.4705 | |
| dc.identifier | Eur.Phys.J.C59:647-658,2009 | |
| dc.identifier | doi:10.1140/epjc/s10052-008-0813-1 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/224157 | |
| dc.subject | High Energy Physics - Phenomenology | |
| dc.title | On the Perturbative Stability of the QCD Predictions for the Ratio $R=F_L/F_T$ in Heavy-Quark Leptoproduction | |
| dc.type | text |