The quasiparticle model is improved by the free magnetic contribution to investigate the QCD matter in a strong magnetic field. The temperature-dependent bag function is determined by the thermodynamic consistency to represent the difference in energy density between physical vacuum and the lowest state of QCD. It is found that the positive bag function vanishes at high temperature, indicating the deconfinement. The rapid decrease of the bag function in stronger magnetic fields reveals the so-called inverse magnetic catalysis. The interaction measure at high temperature remains so large that the usual Stefan-Boltzmann limit cannot be reached. We suggest a limit $|q_i{B}_m|T^2/4$ for each Landau level pressure. Finally, it is demonstrated that the positive magnetization modified by the bag function and free magnetic contribution indicates the paramagnetic characteristic of QCD matter.

• Received 8 August 2023
• Revised 30 November 2023
• Accepted 5 January 2024

DOI:https://doi.org/10.1103/PhysRevC.109.025203

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Published by the American Physical Society