{"title":"双中性介子光生产中的偏振观测。","authors":"The CBELSA/TAPS Collaboration","doi":"10.1140/epja/s10050-025-01612-7","DOIUrl":null,"url":null,"abstract":"<div><p>Measurements of target asymmetries and double-polarization observables for the reaction <img> are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (<span>\\(\\hbox {C}_4\\hbox {H}_9\\)</span>OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from <img> to <img> and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of <img> and <span>\\({\\varDelta ^*}\\)</span> resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6)<span>\\(\\times \\)</span>O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.</p></div>","PeriodicalId":786,"journal":{"name":"The European Physical Journal A","volume":"61 7","pages":""},"PeriodicalIF":2.8000,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12287178/pdf/","citationCount":"0","resultStr":"{\"title\":\"Polarization observables in double neutral pion photoproduction\",\"authors\":\"The CBELSA/TAPS Collaboration\",\"doi\":\"10.1140/epja/s10050-025-01612-7\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Measurements of target asymmetries and double-polarization observables for the reaction <img> are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (<span>\\\\(\\\\hbox {C}_4\\\\hbox {H}_9\\\\)</span>OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from <img> to <img> and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of <img> and <span>\\\\({\\\\varDelta ^*}\\\\)</span> resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6)<span>\\\\(\\\\times \\\\)</span>O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.</p></div>\",\"PeriodicalId\":786,\"journal\":{\"name\":\"The European Physical Journal A\",\"volume\":\"61 7\",\"pages\":\"\"},\"PeriodicalIF\":2.8000,\"publicationDate\":\"2025-07-23\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12287178/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"The European Physical Journal A\",\"FirstCategoryId\":\"4\",\"ListUrlMain\":\"https://link.springer.com/article/10.1140/epja/s10050-025-01612-7\",\"RegionNum\":3,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"PHYSICS, NUCLEAR\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"The European Physical Journal A","FirstCategoryId":"4","ListUrlMain":"https://link.springer.com/article/10.1140/epja/s10050-025-01612-7","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"PHYSICS, NUCLEAR","Score":null,"Total":0}
Polarization observables in double neutral pion photoproduction
Measurements of target asymmetries and double-polarization observables for the reaction are reported. The data were taken with the CBELSA/TAPS experiment at the ELSA facility (Bonn University) using the Bonn frozen-spin butanol (\(\hbox {C}_4\hbox {H}_9\)OH) target, which provided transversely polarized protons. Linearly polarized photons were produced via bremsstrahlung off a diamond crystal. The data cover the photon energy range from to and nearly the complete angular range. The results have been included in the BnGa partial wave analysis. Experimental results and the fit agree very well. Observed systematic differences in the branching ratios for decays of and \({\varDelta ^*}\) resonances are attributed to the internal structure of these excited nucleon states. Resonances which can be assigned to SU(6)\(\times \)O(3) two-oscillator configurations show larger branching ratios to intermediate states with non-zero intrinsic orbital angular momenta than resonances assigned to one-oscillator configurations.
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