Multidimensional partial wave analysis of SIDIS dihadron beam spin asymmetries at CLAS12

Abstract

Dihadron beam spin asymmetries provide a wide range of insights into nucleon structure and hadronization. Recent measurements at CLAS12 provide the first empirical evidence of nonzero G ⊥ 1 , the parton helicity-dependent dihadron fragmentation function (DiFF) encoding spin-momentum correlations in hadronization. These measurements also allow for a point-by-point extraction of the subleading-twist PDF e(x) in a collinear framework. We observe different behavior of the asymmetries in different invariant mass regions, motivating a fully multidimensional study. The DiFFs also expand in terms of partial waves, each corresponding to the interference of dihadrons of particular polarizations. Altogether a fully multidimensional partial wave analysis is needed, and this presentation will summarize the efforts and results obtained thus far.

Opportunities for precision QCD physics in hadronization at Belle II -- a snowmass whitepaper

“…For example, early model calculations assumed that the dominant contribution to the important transverse polarization dependent DiFF H 1 into charged pion pairs originates from the interference of s− and p− wave components, with the former coming from non-resonant pion production and the later coming from unpolarized ρ decays. However, recent preliminary results from CLAS12 [102] indicate that the real mechanism is likely more complex. More details on di-hadron FFs can be found in Ref [58,101].…”