3,4-Dimethyl­anilinium 4-methyl­benzene­sulfonate

In the crystal structure of the title compound, C8H12N+·C7H7O3S−, N—H⋯O hydrogen bonds link the cations and anions into ribbons parallel to the c axis. N—H⋯S inter­actions also occur

Chiral perturbation theory for heavy hadrons and chiral effective field theory for heavy hadronic molecules

Chiral symmetry and its spontaneous breaking play an important role both in the light hadron and heavy hadron systems. In this work, we shall review the investigations on the chiral corrections to the properties of the heavy mesons and baryons within the framework of the chiral perturbation theory ($\chi$PT). We will also review the scatterings of the light pseudoscalar mesons and heavy hadrons. Moreover, the modern nuclear force was built upon the chiral effective field theory ($\chi$EFT). In the past decades many new hadron states were observed experimentally. A large group of these states are near-threshold resonances, such as the charged charmoniumlike $Z_c$ and $Z_{cs}$ states, bottomoniumlike $Z_b$ states, hidden-charm pentaquark $P_c$ and $P_{cs}$ states and the doubly charmed $T_{cc}$ state etc. They are very good candidates of the loosely bound molecular states composed of a pair of charmed hadrons. The same chiral dynamics not only governs the nuclei and forms the deuteron, but also dictates the above shallow bound states or resonances. We will perform an extensive review on the progress on the heavy hadronic molecular states within the framework of $\chi$EFT.Comment: A Review on hadronic molecules in EFT frameworks with 168 pages and 67 figure