Exploring doubly heavy tetraquarks in a constituent-quark-model based meson-meson coupled-channels approach

The LHCb Collaboration announced in 2021 the discovery of a new tetraquarklike state, named <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msubsup><a:mi>T</a:mi><a:mrow><a:mi>c</a:mi><a:mi>c</a:mi></a:mrow><a:mo>+</a:mo></a:msubsup></a:math>, with minimum quark content <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>c</c:mi><c:mi>c</c:mi><c:mover accent="true"><c:mi>u</c:mi><c:mo stretchy="false">¯</c:mo></c:mover><c:mover accent="true"><c:mi>d</c:mi><c:mo stretchy="false">¯</c:mo></c:mover></c:math>, close to the <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msup><i:mi>D</i:mi><i:mn>0</i:mn></i:msup><i:msup><i:mi>D</i:mi><i:mrow><i:mo>*</i:mo><i:mo>+</i:mo></i:mrow></i:msup></i:math> threshold. This has motivated countless theoretical works trying to identify the dynamics which is responsible of the formation of such state; in particular, the one performed by us in Ortega [; ], where a <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:msup><k:mi>D</k:mi><k:mn>0</k:mn></k:msup><k:msup><k:mi>D</k:mi><k:mrow><k:mo>*</k:mo><k:mo>+</k:mo></k:mrow></k:msup></k:math> molecular candidate whose mass, width, scattering length, and effective ranges are in reasonable agreement with experimental measurements. We explore herein the possibility of having <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:msubsup><m:mi>T</m:mi><m:mrow><m:mi>c</m:mi><m:mi>c</m:mi></m:mrow><m:mo>+</m:mo></m:msubsup></m:math> partners in all doubly heavy tetraquark sectors, considering doubly represented light antiquarks <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi>u</o:mi></o:math>, <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"><q:mi>d</q:mi></q:math>, or <s:math xmlns:s="http://www.w3.org/1998/Math/MathML" display="inline"><s:mi>s</s:mi></s:math>, and taking into account all possible spin-parity quantum numbers. The computation is done using a constituent-quark-model based meson-meson coupled-channels framework which has been tested many times in the last fifteen years describing conventional heavy mesons and baryons, their coupling with hadron-hadron thresholds but also in exploring its application to compact multiquark structures. The advantage of using an approach with such a relatively large history is that it allows us to make predictions because all the parameters have already been constrained from our previous works. Then, from this perspective, we present a parameter-free model-dependent prediction of doubly-heavy tetraquarks that may be partners of the discovered <u:math xmlns:u="http://www.w3.org/1998/Math/MathML" display="inline"><u:msubsup><u:mi>T</u:mi><u:mrow><u:mi>c</u:mi><u:mi>c</u:mi></u:mrow><u:mo>+</u:mo></u:msubsup></u:math> state. Published by the American Physical Society 2024