Separated Kaon Electroproduction Cross Section and the Kaon Form Factor from 6 GeV JLab Data

TL;DR

This paper analyzes separated kaon electroproduction cross sections from 6 GeV Jefferson Lab data to extract the kaon form factor, testing QCD predictions and establishing a method for future high-energy experiments.

Contribution

It demonstrates the extraction of the kaon form factor from longitudinal cross sections using a Regge model, extending techniques previously applied to pions.

Findings

Successfully separated cross sections into longitudinal and transverse components.

Extracted kaon form factor consistent with QCD predictions.

Established a method for future high-energy kaon form factor measurements.

Abstract

The $^{1}H$($e,e^\prime K^+$)$\Lambda$ reaction was studied as a function of the Mandelstam variable $-t$ using data from the E01-004 (FPI-2) and E93-018 experiments that were carried out in Hall C at the 6 GeV Jefferson Lab. The cross section was fully separated into longitudinal and transverse components, and two interference terms at four-momentum transfers $Q^2$ of 1.00, 1.36 and 2.07 GeV$^2$. The kaon form factor was extracted from the longitudinal cross section using the Regge model by Vanderhaeghen, Guidal, and Laget. The results establish the method, previously used successfully for pion analyses, for extracting the kaon form factor. Data from 12 GeV Jefferson Lab experiments are expected to have sufficient precision to distinguish between theoretical predictions, for example recent perturbative QCD calculations with modern parton distribution amplitudes. The leading-twist behavior for light mesons is predicted to set in for values of $Q^2$ between 5-10 GeV$^2$, which makes data in the few GeV regime particularly interesting. The $Q^2$ dependence at fixed $x$ and $-t$ of the longitudinal cross section we extracted seems consistent with the QCD factorization prediction within the experimental uncertainty.