# Positivity conditions on the spin density matrix: A simple parametrization

@article{Chung1975PositivityCO, title={Positivity conditions on the spin density matrix: A simple parametrization}, author={S. U. Chung and T. Laurence Trueman}, journal={Physical Review D}, year={1975}, volume={11}, pages={633-646} }

A simple parametrization of the spin density matrix $\ensuremath{\rho}$ is given which ensures that $\ensuremath{\rho}$ is a positive, Hermitian matrix which satisfies the parity symmetry conditions. There is a minimal number of parameters and they can vary independently; no complicated constraints on their allowed region of variation are required. A similar parametrization is given for the real part of $\ensuremath{\rho}$. Rank conditions, polarized targets, and angular distributions are also…

## 53 Citations

Status of exotic-quantum-number mesons

- Physics
- 2010

The search for mesons with non-quark-antiquark (exotic) quantum numbers has gone on for nearly 30 years. Currently there is experimental evidence of three isospin one states, the…

Spin correlations in polarizations of P-wave charmonia $\chi_{cJ}$ and impact on $J/\psi$ polarization

- Physics
- 2014

Based on a general form of the effective vertex functions for the decays of P-wave charmonia $\chicj$, angular distribution formulas for the subsequent decays $\chicj\rightarrow \jpsi \gamma$ and…

Moments of angular distribution and beam asymmetries in
ηπ0
photoproduction at GlueX

- PhysicsPhysical Review D
- 2019

In the search for exotic mesons, the GlueX collaboration will soon extract moments of the $\eta\pi^0$ angular distribution. In the perspective of these results, we generalize the formalism of moment…

Spin-parity analysis of the ƒ1(1285)π− system in the reaction π−p → ƒ1(1285)π−p at 18 GeV / c

- Physics
- 1994

Abstract We have carried out a study of the reaction π − p → ƒ 1 (1285) π − p at 18 GeV / c , with ƒ 1 (1285) → K + K 0 π − This reaction is almost entirely mediated by the natural-parity exchange,…

The generators of Lorentz transformation in momentum space

- Physics
- 2002

In the momentum space, the angular momentum operator and the boost vector operator, i.e. the generators for the Lorentz transformation of a particle with arbitrary spin and nonzero mass are…

Model Selection for and Partial-Wave Analysis of a Five-Pion Final State at the COMPASS Experiment at CERN

- Physics
- 2016

The light-meson spectrum is an important ingredient to understand quantum chromodynamics, the theory of strong interaction at low energies, where quarks and gluons are confined into hadrons. However,…

Light Scalar Mesons in Central Production at COMPASS

- Physics
- 2016

COMPASS is a fixed-target experiment at the CERN SPS that studies the spectrum of light-quark hadrons. In 2009, it collected a large dataset using a 190 GeV/c positive hadron beam impinging on a…

The beam-helicity asymmetry for γp → pK+K− and γp → pπ+ π−

- Physics
- 2016

The first-time measurement of the angular dependence of the beam-helicity asymmetry for γp → pK+ K− is shown and compared to γp → pπ+ π−. The data obtained were from the CLAS g12 experiment at…

Analysis of the reaction π−Be → π−π0π0Be at VES

- Physics
- 2016

We present the results of the analysis of diffractive reaction π−Be → π−π0π0Be measured with upgraded VES detector with the statistics of about 16 · 106 events. The mass-independent partial-wave…

Ambiguities in model-independent partial-wave analysis

- PhysicsPhysical Review D
- 2018

Partial wave analysis is an important tool for analyzing large data sets in hadronic decays of light and heavy mesons. It commonly relies on the isobar model, which assumes multihadron final states…