Measurement of Spin-Density Matrix Elements in $\Delta^{++}(1232)$ photoproduction

The GlueX collaboration
Phys.Lett.B 863 (2025) 139368, 2025.

Abstract
We measure the spin-density matrix elements (SDMEs) of the $\Delta^{++}(1232)$ in the photoproduction reaction $\gamma p \to \pi^-\Delta^{++}(1232)$ with the GlueX experiment in Hall D at Jefferson Lab. The measurement uses a linearly--polarized photon beam with energies from $8.2$ to $8.8$~GeV and the statistical precision of the SDMEs exceeds the previous measurement by three orders of magnitude for the momentum transfer squared region below $1.4$ GeV$^2$. The data are sensitive to the previously undetermined relative sign between couplings in existing Regge-exchange models. Linear combinations of the extracted SDMEs allow for a decomposition into natural and unnatural--exchange amplitudes. We find that the unnatural exchange plays an important role in the low momentum transfer region.

  • Delta^{++}(1232) Spin Density Matrix Elements

    Data from Figure 3

    10.17182/hepdata.153414.v2/t1

    Spin-density matrix elements for the photoproduction of $\Delta(1232)^{++}$ in the Gottfried-Jackson system. The first uncertainty is statistical, the second systematic.

Version 2 modifications: Version submitted to arXiv and PLB

Loading Data...

Ask a Question


Your question will be emailed to those involved with the submission. Please mention the relevant table.


Please log in to HEPData to send a question.