Photo- and Electrocouplings of Nucleon Resonances

Nucleon axial form factor at large momentum transfers

“…Comparing our prediction with available data on this domain [31], there is agreement within mutual uncertainties. It is worth stressing that our results are parameter-free predictions; especially because the framework employed is precisely the same as that used elsewhere in the explanation and prediction of nucleon elastic form factors [4] and the electroexcitation amplitudes of the Δ(1232) 3 2 + and N (1440) 1 2 + [62][63][64]. Hence, the agreement is meaningful, providing support for the picture of emergent hadron mass expressed in our formulation of the baryon bound-state problem [65][66][67].…”

Nucleon Resonance Electroexcitation Amplitudes and Emergent Hadron Mass

“…If we do not understand how QCD generates these bound states of three dressed quarks, then our understanding of Nature is incomplete. Remarkable progress has been achieved in recent decades through the studies of the structure of the ground and excited nucleon states in experiments at JLab during the 6-GeV era [1,28,[47][48][49]72,155,156]. These experiments have provided a large array of new opportunities for QCD-connected hadron structure theory by opening a door to the exploration of many hitherto unseen facets of the strong interaction in the regime of large running coupling, i.e., α s /π 0.2, by providing the results on the γ v pN * electrocouplings for numerous N * states, with different quantum numbers and structural features.…”

“…Systematic studies of N * electroexcitation from the data became feasible only after experiments during the 6-GeV era with the CLAS detector in Hall B at JLab. This detector has collected the dominant part of available world data on most single-and multi-meson electroproduction channels off protons in the resonance region for Q 2 up to 5 GeV 2 [47][48][49]72,75]. The data are stored in the CLAS Physics Database [116,117].…”

“…In the northern spring of 2018, after completion of the 12-GeV-upgrade project, measurements with the CLAS12 detector in Hall B at JLab commenced [47,48,150]. Currently, CLAS12 is the only facility in the world capable of exploring exclusive meson electroproduction in the resonance region, exploiting the highest Q 2 ever achieved for these processes.…”

Origin of the Proton Mass

“…For example, theory predicts that many excited states of the proton also contain pseudoscalar and vector diquark correlations. This can be tested in resonance electroexcitation measurements [71][72][73]. In addition, electroweak transitions between heavy+light mesons, in which HB couplings are the dominant source of In each case, the like coloured band expresses the response to a ±5% variation in ζ H .…”