Topic: Δ(1232) axial-vector and pseudoscalar form factors from the continuum Schwinger function methods

Speaker: Tenure-track Assoc. Prof. Chen Chen

Coordinates: PCFT C1124, 4pm, Thursday, October 20

Abstract: Nucleon properties are largely determined by the strong interaction; and a central aim of on-going experimental and theoretical efforts is to understand their structure as composite objects made of three valence light quarks.  Electron+nucleon scattering is a well developed experimental technique in such studies and it has delivered, for instance, precise measurements of nucleon electromagnetic and transition form factors.  An entirely new window onto nucleon and baryon structure is opened when one uses neutrino scattering.  Indeed, reliable predictions of nucleon (N) and N-to-∆(1232) electroweak form factors are crucial for understanding new-generation long-baseline neutrino oscillation experiments.  Recent developments within the framework of continuum Schwinger function methods (CSMs) have enabled practitioners to deliver the first Poincaré-invariant parameter-free predictions for such form factors on a momentum transfer domain that extends to Q2=10GeV2 and beyond.  Where data are available, the predictions confirm the measurements.  More importantly, the results are serving as motivation for new experiments at high-luminosity facilities.  This presentation will describe these developments and also their extension to ∆(1232) axialvector and pseudoscalar form factors.  The latter cannot be measured, but they have been computed using lattice-regularised QCD; and comparisons between these two nonperturbative approaches to strong interactions within the Standard Model are instructive.  Solving QCD is a hard problem and a many-pronged approach offers the best hope for success.