Azimuthal asymmetry and ratio R = F L /F T as probes of the charm content of the proton

Abstract

We study two experimental ways to measure the heavy-quark content of the proton: using the Callan-Gross ratio R(x, Q 2 ) = FL/FT and/or azimuthal cos(2ϕ) asymmetry in deep inelastic leptonnucleon scattering. Our approach is based on the perturbative stability of the QCD predictions for these two quantities. We resume the mass logarithms of the type αs ln Q 2 /m 2 and conclude that heavy-quark densities in the nucleon can, in principle, be determined from data on the CallanGross ratio and/or azimuthal asymmetry. In particular, the charm content of the proton can be measured in future studies at the proposed Large HadronElectron (LHeC) and ElectronIon (EIC) Colliders.

On the intrinsic bottom content of the nucleon and its impact on heavy new physics at the LHC

“…At a future Electron-Ion Collider (EIC) the large-x charm structure function would be accessible, and the rate for charm production at x 0.1 could be increased by up to an order of magnitude due to the presence of a large-x non-perturbative intrinsic charm component in the nucleon [32]. Alternatively, the IC could be searched for by measuring the Callan-Gross ratio R(x, Q 2 ) = F L /F T [33], or by studying angular distributions [34,35].…”