Spin Information from Vector-Meson Decay in Photoproduction

Abstract

For the photoproduction of vector mesons, all single and double spin observables involving vector meson two-body decays are defined consistently in the $\gamma N$ center of mass. These definitions yield a procedure for extracting physically meaningful single and double spin observables that are subject to known rules concerning their angle and energy evolution. As part of this analysis, we show that measuring the two-meson decay of a photoproduced $\rho$ or $\varphi$ does not determine the vector meson's vector polarization, but only its tensor polarization. The vector meson decay into lepton pairs is also insensitive to the vector meson's vector polarization, unless one measures the spin of one of the leptons. Similar results are found for all double spin observables which involve observation of vector meson decay. To access the vector meson's vector polarization, one therefore needs to either measure the spin of the decay leptons, make an analysis of the background interference effects or relate the vector meson's vector polarization to other accessible spin observables.

22 pages, 3 figures

References in corpus (1)

• Completeness Rules for Spin Observables in Pseudoscalar Meson Photoproduction

Cited by in corpus (14)

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• Measurement of Spin-Density Matrix Elements in $\rho (770)$ Production with a Linearly Polarized Photon Beam at $E_{\gamma }=8.2-8.8\text{GeV}$
• Spin asymmetries in gamma + N --> K*bar + Theta^+
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• Constraints on vector meson photoproduction spin observables
• Model-independent aspects of the reaction $\bar{K}+N\to K+\Xi$
• Photoproduction of electron-positron pairs on the proton in the resonance region
• Irreducible tensor approach to spin observables in photo production of mesons with arbitrary spin-parity $s^{\pi }$
• Angular Distributions, Polarization Observables, Spin Density Matrices and Statistical Tensors in Photoproduction of Two Pseudoscalar Mesons off a Nucleon