Polarization and dilepton anisotropy in pion-nucleon collisions

Abstract

Hadronic polarization and the related anisotropy of the dilepton angular distribution are studied for the reaction $\pi N\to N{e}^{+}{e}^{-}$. We employ consistent effective interactions for baryon resonances up to spin-5/2, where non-physical degrees of freedom are eliminated, to compute the anisotropy coefficients for isolated intermediate baryon resonances. It is shown that the spin and parity of the intermediate baryon resonance is reflected in the angular dependence of the anisotropy coefficient. We then compute the anisotropy coefficient including the $N(1520)$ and $N(1440)$ resonances, which are essential at the collision energy of the recent data obtained by the HADES collaboration on this reaction. We conclude that the anisotropy coefficient provides useful constraints for unravelling the resonance contributions to this process.

11 pages, 5 figures, version accepted for publication in Physics Letters B

References in corpus (6)

• Big-Bang Nucleosynthesis
• Determination of the X(3872) meson quantum numbers
• Measurement of $J/\psi$ polarization in $pp$ collisions at $\sqrt{s}=7$ TeV
• Model-independent constraints on the shape parameters of dilepton angular distributions
• Angular distributions of leptons from J/psi's produced in 920 GeV fixed-target proton-nucleus collisions
• Dilepton production in pion-nucleon collisions in an effective field theory approach

Cited by in corpus (7)

• The $\varphi$ meson with finite momentum in a dense medium
• Dilepton Radiation from Strongly Interacting Systems
• Virtual photon polarization and dilepton anisotropy in relativistic nucleus-nucleus collisions
• Virtual photon polarization in ultrarelativistic heavy-ion collisions
• Role of baryon resonances in the ${\pi }^{-}p\to n{e}^{+}{e}^{-}$ reaction within an effective-Lagrangian model
• Structure of virtual photon polarization in ultrarelativistic heavy-ion collisions
• Polarization and dilepton angular distribution in pion-nucleon collisions