Quasifragmentation functions in the massive Schwinger model

TL;DR

This paper introduces the quark quasifragmentation function (qFF) in the massive Schwinger model, deriving it for fermions in QED2, and compares computational results with theoretical predictions across different coupling regimes.

Contribution

It presents the first formulation of the qFF in the massive Schwinger model and develops a quantum-computation-friendly method for its calculation.

Findings

Exact diagonalization of the spin Hamiltonian yields qFF results.

Comparison shows agreement with Drell-Levy-Yan predictions at various couplings.

Method is suitable for quantum simulations of fragmentation functions.

Abstract

We introduce the concept of the quark quasifragmentation function (qFF) using an equal-time and spatially boosted form of the Collins-Soper fragmentation function where the out-meson fragment is replaced by the current asymptotic condition. We derive the qFF for a fermion in two-dimensional quantum electrodynamics (QED2) using the Kogut-Susskind Hamiltonian after a mapping onto spin qubits in a spatial lattice with open boundary conditions. This form is suitable for quantum computations. We compute the qFF by exact diagonalization of the spin Hamiltonian. The results are compared to the qFF following from the Drell-Levy-Yan result for QED2, both at strong and weak coupling, and to two-dimensional quantum chromodynamics in the lowest Fock approximation.