Theory Seminar: Utku Can

Conference Date
Conference Location

CEBAF Center F224-225

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Speaker: Utku Can (University of Adelaide)

Title: Compton Amplitude and the Nucleon Structure Functions from a Lattice QCD Calculation

Abstract: The structure of hadrons relevant for deep-inelastic scattering are completely characterised by the Compton amplitude. The standard approach in structure function calculations is to utilise the operator product expansion (OPE). However, it is well established in the lattice community that computing higher-twist contributions presents additional challenges that are not easily overcome; complicating the investigations of hadron structure at a deeper level. Alternatively, it is possible to directly calculate the Compton amplitude by taking advantage of the familiar Feynman-Hellmann approach applied in the context of lattice QCD. By working with the physical amplitude, the intricacies of operator mixing and renormalisation that plague the OPE approach are circumvented. Additionally, higher-twist contributions become more accessible.

In this talk, I will be highlighting QCDSF/UKQCD Collaboration's recent developments on computing the Compton amplitude. I discuss how to access the Compton amplitude directly via the second-order Feynman-Hellmann theorem. I will present our nucleon Compton amplitude results for different structure functions across a range of photon momenta. This enables us to study the $Q^2$ dependence of the low moments of the nucleon structure functions in a lattice calculation. I will also discuss possible further applications of this approach and present some preliminary results.