Spin Orbit Correlations and the Structure of the Nucleon

Extraction of the higher-twist parton distribution $e(x)$ from CLAS data

“…This is achieved through the estimate of the ratio of integrated DiFFs n ↑ u /n u at the relevant kinematics (provided in Ref. [38]) together with the ratio of helicity to unpolarized PDFs, on the (x, z, M h )-triptych 4 .…”

“…As such, those were thought as natural candidates to clarify the origin of large transverse polarization effects in observables, an hypothesis that is still explored today, e.g. [4,5]. Higher-twist corrections are understood in phenomenology as terms that are suppressed w.r.t.…”

“…See Eq. (A6) below 4. Notice that COMPASS asymmetries are corrected by the depolarization factor W (y)/A(y), or K 3 .…”

Light-Front Transverse Momentum Distributions for ${\cal J}$=1/2 Hadronic Systems in Valence Approximation

“…As a matter of fact, one can address the correlations between spin and momentum, substantially deepening our understanding of the inner dynamics. For the nucleon, TMDs (see, e.g., [9][10][11][12][13][14][15][16][17][18][19] are the object of impressive theoretical and experimental efforts, both in semi-inclusive deep inelastic scattering (SIDIS) and in Drell-Yan processes (see, e.g., [20][21][22][23][24][25][26][27][28] and [29][30][31], respectively). In particular light-cone models and phenomenological approaches for the TMDs have been used, e.g., (i) to study the threedimensional nucleon structure [32][33][34][35][36][37][38], (ii) to address the nucleon-spin puzzle [39] and (iii) hence to disentangle the contributions of different angular-momentum components to the spin of the nucleon [40,41].…”

Structure of the nucleon at leading and subleading twist in the covariant parton model

“…Aspects of TMD physics were reviewed in Refs. [47][48][49][50][51][52]. An important complement of the theoretical and phenomenological studies is provided by studies in models.…”