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Dynamical study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>D</mml:mi></mml:mrow><mml:mrow><mml:mo>*</mml:mo></mml:mrow></mml:msup><mml:mi>D</mml:mi><mml:mi>K</mml:mi></mml:mrow></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>D</mml:mi><mml:mo>*</mml:mo></mml:msup><mml:mi>D</mml:mi><mml:mover accent="true"><mml:mi>D</mml:mi><mml:mo stretchy="false">¯</mml:mo></mml:mover></mml:math> systems at quark level

Inspired by the recent report from the LHCb Collaboration on Tcc, which can be interpreted as a molecular DD*, we investigated two trimeson systems of the Tcc partner with IJP=01− in the framework of a chiral quark model. In the first case, because of the attraction between D* and D¯, we explored the existence of bound states in the system D*DD¯, which is obtained by adding D¯ into the molecular bound state Tcc (DD*). Similarly, in the second case, we explored whether there is a bound state in the D*DK system, which is obtained by adding K into the Tcc, given the attraction between D and K. The results show that both of them are bound states, in which the binding energy of the molecular state DD*K is relatively small, only 0.4±0.4 MeV, while the binding energy of DD*D¯ is up to 1.6±0.3 MeV. According to the calculation results of the root-square-mean distances, the spatial structure of the two systems shows the obvious (DD*)−(D¯/K) structure, in which D is close to D* while DD* as a whole is relatively distant from the third hadron (D¯/K), which are similar to the nucleon-electron structure. As a result, we strongly recommend that these bound states DD*D¯ and DD*K are searched for experimentally. Published by the American Physical Society 2024

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Constitutive Relationship of Soil in Contact with Mortar under Continuous Loading

Abstract Mortars will remain critical in future land wars due to their flexibility and versatility. When mortars are fired continuously, the contact soil is gradually compacted by the mortar base plate, and dynamic research into this process is the basis for innovative mortar design. However, the discontinuity and nonlinearity of soil contact absolutely necessitate the constitutive relationship of soil contact, which is difficult to study. Therefore, this study conducted experimental research and theoretical derivation to establish an accurate dynamic model of the mortar system. First, based on the nonlinear elastic-plastic theory and the stress-strain relationship of soil under cyclic loading, a theoretical analysis method for the constitutive relationship of contact soil under continuous loading was proposed. Second, an experimental and testing system was designed to simulate launch loads, and the stress-strain response of soil under continuous impact loads was obtained experimentally. Subsequently, based on theoretical analysis and experimental data, the stress-strain relationship during the gradual compaction of soil was established using the least squares method. Finally, a constitutive relationship model of the contact soil in the mortar system was established in ABAQUS using the VUMAT subroutine interface, and the calculated results were compared and analyzed with traditional calculation results. The results indicated that studying the constitutive relationship of mortar in contact with soil during continuous firing using this method can improve the accuracy of dynamically modeling mortar systems. Moreover, this study has practical value in the engineering design of mortar systems.

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