<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-08-01T01:47:07Z</responseDate><request verb="GetRecord" identifier="oai:docta.ucm.es:20.500.14352/50793" metadataPrefix="marc">https://docta.ucm.es/rest/oai/request</request><GetRecord><record><header><identifier>oai:docta.ucm.es:20.500.14352/50793</identifier><datestamp>2023-08-27T12:52:52Z</datestamp><setSpec>com_20.500.14352_14</setSpec><setSpec>col_20.500.14352_15</setSpec></header><metadata><record xmlns="http://www.loc.gov/MARC21/slim" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.loc.gov/MARC21/slim http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd">
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      <subfield code="a">dc</subfield>
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   <datafield ind2=" " ind1=" " tag="720">
      <subfield code="a">Llanes Estrada, Felipe José</subfield>
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      <subfield code="a">General, Ignacio J.</subfield>
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   <datafield ind2=" " ind1=" " tag="720">
      <subfield code="a">Wang, Ping</subfield>
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      <subfield code="a">Cotanch, Stephen R.</subfield>
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   <datafield ind2=" " ind1=" " tag="260">
      <subfield code="c">2007-09-30</subfield>
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      <subfield code="a">Highlights in the search for nonconventional (non-q.q) meson states are the π1(1400) and π1(1600) exotic candidates. Should they exist, mounting theoretical arguments suggest that they are tetraquark molecular resonances excitable by meson rescattering.We report a new tetraquark calculation within a model field theory approximation to Quantum Chromodynamics in the Coulomb gauge supporting this conjecture. We also strengthen this claim by  consistentlycontrasting results with exotic state predictions for hybrid (q . qg) mesons within the same theoretical framework. Our findings confirm that molecular like configurations involving two color singlets (a resonance, not a bound state) are clearly favored over hybrid or color-exotic tetraquark meson (q . qq.q atoms) formation. Finally, to assist needed further experimental searches we document a useful off-plane correlator for establishing the structure of these exotic systems along with similar, but anticipated much narrower, states that should exist in the charmonium and bottomonium spectra.</subfield>
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      <subfield code="a">0370-2693</subfield>
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      <subfield code="a">10.1016/j.physletb.2007.08.015</subfield>
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      <subfield code="a">https://hdl.handle.net/20.500.14352/50793</subfield>
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   <datafield ind1="8" ind2=" " tag="024">
      <subfield code="a">http://dx.doi.org/10.1016/j.physletb.2007.08.015</subfield>
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      <subfield code="a">http://arxiv.org/abs/0707.1286</subfield>
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      <subfield code="a">http://www.sciencedirect.com</subfield>
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   <datafield ind2="0" ind1="0" tag="245">
      <subfield code="a">Light 1(-+) exotics: molecular resonances</subfield>
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