Spectrum of the molecular tetraquarks: Unraveling the Tcs0(2900) and <…

We relate the interactions of the D¯(*)K* and D(*)K* systems to those of D(*)D(*) and D(*)D¯(*) respectively, considering the residual strong interactions at the near-threshold energy is too weak to excite the strange quarks inside the hadrons. We propose an effective model to describe the low-energy S-wave interactions that are undertaken by the light u, d quarks between two separated heavy hadrons. We find that the existence of molecules in the heavy-(anti)heavy sectors will naturally lead to the emergence of molecular states in D¯(*)K* and D(*)K* systems. The recently observed Tcs0(2900) and Tcs¯0a(2900) can be well identified as the 0(0+) and 1(0+) partners of Tcc(3875) and Zc(3900) in the charmed strange sector, respectively. We also predict their members under the (c and s) quark symmetry and SU(2) flavor symmetry. Most of them are very good molecule candidates, for example, (i) the 0(1+) states in D*D*, D¯K*, D¯*K*; (ii) the 0(+)(2+(+)) states in D*D¯*, D¯*K*, D*K*; (iii) the 1−(0++) state in D*D¯* and 1(1+) state in D*K*. The 0+(0++) state in DD¯ and the 0(1+) state in DK* might also exist as virtual states, and the 0(1+) DK* can serve as a key to infer the existence of 0+(0++) DD¯. The Dsπ invariant mass spectrum of Tcs¯0a(2900) is also studied within the coupled-channel approach, and the molecular interpretation of Tcs¯0a(2900) is consistent with the experimental data. Searching for the predicted states in experiments is crucial to discriminate the different pictures for interpreting these near-threshold exotica. Published by the American Physical Society 2024