Search for tetraquark states X$_{cc\overline{ss}}$ in D$_{s}$$^{+}$ D$_{s}$$^{+}$ ( D$_{s}$$^{*+}$ D$_{s}$$^{*+}$) final states at Belle

A search for double-heavy tetraquark state candidates X$_{cc\overline{ss}}$ decaying to D$_{s}$$^{+}$ D$_{s}$$^{+}$ and D$_{s}$$^{*+}$ D$_{s}$$^{*+}$ is presented for the first time using the data samples of 102×10$^{6}$ Υ(1S) and 158×10$^{6}$ Υ(2S) events, and the data samples at $\sqrt{s}$=10.52, 10.58, and 10.867 GeV corresponding to integrated luminosities of 89.5, 711.0, and 121.4 fb$^{-1}$, respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the D$_{s}$$^{+}$ D$_{s}$$^{+}$ and D$_{s}$$^{*+}$ D$_{s}$$^{*+}$D are studied to search for possible resonances. No significant signals are observed, and the 90% confidence level upper limits on the product branching fractions [B(Υ(1S,2S)→X$_{cc\overline{ss}}$ anything)×B(X$_{cc\overline{ss}}$ →D$_{s}$$^{+}$ D$_{s}$$^{+}$ D$_{s}$$^{*+}$ D$_{s}$$^{*+}$))]in Υ(1S,2S) inclusive decays and the product values of Born cross section and branching fraction [σ(e$^{+}$e$^{-}$→X$_{cc\overline{ss}}$ + anything)×B(X$_{cc\overline{ss}}$→ D$_{s}$$^{+}$ D$_{s}$$^{+}$ D$_{s}$$^{*+}$ D$_{s}$$^{*+}$))] in e$^{+}$e$^{-}$ collisions at $\sqrt{s}$=10.52, 10.58, and10.867 GeV under different assumptions of X$_{cc\overline{ss}}$ masses and widths are obtained.