I think that https://www.nature.com/articles/546185b is a popular summary of the paper to which Anton Vrdoljak linked. However, it is not about a new meson but about meson decays. As the author of the article in Nature wrights, the results "could crack open the standard model".
Here is a paper by another collaboration including several authors from the University of Michigan about an (unsuccessful) search for the Exotic Meson X ( 5568 ): https://www.researchgate.net/publication/325232590