Gauge Sector Dynamics in QCD

Abstract

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Non-perturbative strong coupling at timelike momenta

“…During the past two decades, lattice QCD results for Landau gauge two-point functions have advanced to an impressive quantitative level of precision; see, e.g., [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64]. A recent review of lattice and functional results can be found in [65]. The lattice ghost dressing function and gluon propagator data used in this work have been obtained from recent calculations with 2+1 dynamical fermion flavours at the physical point [32,33].…”

Nucleon Resonance Electroexcitation Amplitudes and Emergent Hadron Mass

“…The sum of the current masses of these quarks, which is generated by Higgs couplings into QCD, accounts for less than 2% of the measured nucleon masses (see Table 1). This accounting clearly indicates that the overwhelmingly dominant component of the nucleon mass is created by mechanisms other than those associated with the Higgs boson [8][9][10][11][12][13][14][15].…”

“…A decade of rapid progress in the development and application of CSMs in hadron physics [5][6][7][8][9][10][11][12][13][14][15], complemented by advances in and results from lattice QCD (lQCD) [16][17][18][19][20][21][22][23][24][25], have delivered numerous predictions for properties of mesons and baryons within a common theoretical framework. Studies of hadron structure from data obtained in experiments with electromagnetic probes at JLab [1,[26][27][28][29], MAMI [30][31][32][33][34][35], and Babar and Belle [36,37], have provided experimental results that can be confronted with predictions from the QCD-connected approaches to hadron structure.…”

“…(Current quark masses listed at a scale of 2 GeV, but the comparison remains qualitatively unchanged if renormalization group invariant current masses are used.) conclusively demonstrated that the dominant part of each hadron's mass is generated by strong interactions in the regime of large QCD running coupling [1,[8][9][10][11][12][13][14][15]73]. Solving QCD's equationsof-motion for the gluon and quark fields has revealed the emergence of quasiparticles, with the quantum numbers of the Lagrangian partons but carrying momentum-dependent masses that are large in the sQCD domain.…”

“…Herein, too, we present the first preliminary experimental results on these amplitudes, obtained from analysis of π + π − p electroproduction data off protons in the W-range up to 1.7 GeV and 2 < Q 2 /GeV 2 < 5 using the JLab-Moscow State University (JM) meson-baryon reaction model [67,[80][81][82][83]. Comparison between the CSM predictions and these experimental results represents a further sensitive test of the capability for validating the EHM paradigm [8][9][10][11][12][13][14][15].…”