Photoproduction of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mi mathvariant="normal">Σ</mml:mi><mml:mo>+</mml:mo></mml:msup></mml:math> hyperon using linearly polarized photons with CLAS
Abstract
Measurements of the polarization observables <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi mathvariant="normal">Σ</a:mi><a:mo>,</a:mo><a:mi mathvariant="bold">P</a:mi><a:mo>,</a:mo><a:mi mathvariant="bold">T</a:mi><a:mo>,</a:mo><a:msub><a:mi mathvariant="bold">O</a:mi><a:mi mathvariant="bold">x</a:mi></a:msub><a:mo>,</a:mo><a:msub><a:mi mathvariant="bold">O</a:mi><a:mi mathvariant="bold">z</a:mi></a:msub></a:mrow></a:math> for the reaction <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:mrow><i:mover accent="true"><i:mi>γ</i:mi><i:mo>⃗</i:mo></i:mover><i:mi>p</i:mi><i:mo>→</i:mo><i:msubsup><i:mi>K</i:mi><i:mrow><i:mi>S</i:mi></i:mrow><i:mn>0</i:mn></i:msubsup><i:msup><i:mi mathvariant="normal">Σ</i:mi><i:mo>+</i:mo></i:msup></i:mrow></i:math> using a linearly polarized photon beam of energy 1.1 to 2.1 GeV are reported. The measured data provide information on a channel that has not been studied extensively, but is required for a full coupled-channel analysis in the nucleon resonance region. Observables have been simultaneously extracted using likelihood sampling with a Markov-Chain Monte Carlo process. Angular distributions in bins of photon energy <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"><l:msub><l:mi>E</l:mi><l:mi>γ</l:mi></l:msub></l:math> are produced for each polarization observable. <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"><m:mrow><m:mi mathvariant="bold">T</m:mi><m:mo>,</m:mo><m:msub><m:mi mathvariant="bold">O</m:mi><m:mi mathvariant="bold">x</m:mi></m:msub></m:mrow></m:math>, and <q:math xmlns:q="http://www.w3.org/1998/Math/MathML"><q:msub><q:mi mathvariant="bold">O</q:mi><q:mi mathvariant="bold">z</q:mi></q:msub></q:math> are first time measurements of these observables in this reaction. The extraction of <t:math xmlns:t="http://www.w3.org/1998/Math/MathML"><t:mi mathvariant="normal">Σ</t:mi></t:math> extends the energy range beyond a previous measurement. The measurement of <v:math xmlns:v="http://www.w3.org/1998/Math/MathML"><v:mi mathvariant="bold">P</v:mi></v:math>, the recoil polarization, is consistent with previous measurements. The measured data are shown to be significant enough to affect the estimation of the nucleon resonance parameters when fitted within a coupled-channels model.
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