Speaker
Description
Higher-twist effects reflect the physics of quark-quark and quark-gluon correlations that provide unique insights into the dynamics inside hadrons that goes beyond the parton model. These effects are sub-leading (suppressed by powers of $1/Q^2$) but crucial for quantitative analyses and precision tests of QCD. By their nature higher-twist contributions are non-perturbative. In this contribution, we report on QCDSF Collaboration's calculations of the Compton amplitude on 2+1-flavour ensembles with varying quark masses corresponding to $m_\pi = [410, 360, 300, 265]$ MeV, at a fixed volume of $V=48^3 \times 96$ and coupling $\beta = 5.65$ ($a = 0.068(3)$ fm). By extracting the lowest even isovector moment of the nucleon $F_2$ structure function, we quantify the quark mass dependence of the higher-twist effects. Our preliminary results indicate a significant quark mass dependence towards the low-$Q^2$ ($\sim 1 \; {\rm GeV}^2$) region.
| Parallel Session (for talks only) | Structure of hadrons and nuclei |
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