arXiv subjects

Silvia Pisano

Publications and source records attributed to Silvia Pisano.

4 recordsLinked to original sources

arXiv2022

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

This manuscript presents the new analysis of recent CLAS and CLAS12 data aimed at the extraction of $e(x)$. This publication benefits from a proof-of-principle analysis of a smaller preliminary data set published in a preprint form in \url{1405.7659}. We present the first point-by-point extraction of a twist-3 PDF. The scalar PDF, $e(x)$, is accessed through the analysis of the data for the $\sinϕ_R$-moment of the beam-spin asymmetry for dihadron production in semi-inclusive DIS off proton target at CLAS and CLAS12. The dihadron formalism allows for use of collinear framework, hence calling for a minimal set of approximations and hypotheses. The extracted PDF $e(x)$ carries insights into the physics of the largely-unexplored quark-gluon correlations, and its first Mellin moment is related to the marginally-known scalar charge of the nucleon. We show that the proton flavor combination of the scalar PDF is non-zero at more than $74\%$ probability.

hep-ph↗

arXiv2016

Summary of WG6: Spin Physics

The working group on Spin Physics at the XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2016) witnessed a significant progress in the theoretical and experimental investigations aiming at unveiling the innermost structure of the proton. Results ranged from proton's one-dimensional representation to its multi-dimensional imaging. In this contribution, we summarize a selection of the topics discussed and of the results presented. For details, we refer to the individual contributions collected in the proceedings of this workshop.

hep-ph↗

arXiv2015

Di-hadron fragmentation and mapping of the nucleon structure

The fragmentation of a colored parton directly into a pair of colorless hadrons is a non-perturbative mechanism that offers important insights into the nucleon structure. Di-hadron fragmentation functions can be extracted from semi-inclusive electron-positron annihilation data. They also appear in observables describing the semi-inclusive production of two hadrons in deep-inelastic scattering of leptons off nucleons or in hadron-hadron collisions. When a target nucleon is transversely polarized, a specific chiral-odd di-hadron fragmentation function can be used as the analyzer of the net density of transversely polarized quarks in a transversely polarized nucleon, the so-called transversity distribution. The latter can be extracted through suitable single-spin asymmetries in the framework of collinear factorization, thus in a much simpler framework with respect to the traditional one in single-hadron fragmentation. At subleading twist, the same chiral-odd di-hadron fragmentation function provides the cleanest access to the poorly known twist-3 parton distribution $e(x)$, which is intimately related to the mechanism of dynamical chiral symmetry breaking in QCD. When sensitive to details of transverse momentum dynamics of partons, the di-hadron fragmentation functions for a longitudinally polarized quark can be connected to the longitudinal jet handedness to explore possible effects due to $CP-$violation of the QCD vacuum. In this review, we outline the formalism of di-hadron fragmentation functions, we discuss different observables where they appear and we present measurements and future worldwide plans.

hep-ph↗

arXiv2008

Electromagnetic Decays of Vector Mesons in a Covariant Model

A fully covariant model for describing the electromagnetic decay of Vector Mesons, both in light and in heavy sectors, is presented. The main ingredients of our approach are i) an Ansatz for the Bethe-Salpeter vertex for Vector Mesons, and ii) a Mandelstam-like formula for the electromagnetic decay constant. The free parameters of our approach are fixed through a comparison with the transverse momentum distribution obtained within a Light-Front Hamiltonian Dynamics framework with constituent quarks. Preliminary results for both the decays constants and the probability of the valence component are shown.

hep-ph↗