Search for tetraquark states $X_{cc\bar{s}\bar{s}}$ in $D_s^{+}{D}_s^{+}(D_s^{\ast +}{D}_s^{\ast +})$ final states at Belle

Abstract

A search for double-heavy tetraquark state candidates $X_{cc\bar{s}\bar{s}}$ decaying to $D_s^{+}{D}_s^{+}$ and $D_s^{\ast +}{D}_s^{\ast +}$ is presented for the first time using the data samples of 102 million ${\rm Y}(1S)$ and 158 million ${\rm Y}(2S)$ events, and the data samples at $\sqrt{s}$ = 10.52~GeV, 10.58~GeV, and 10.867~GeV corresponding to integrated luminosities of 89.5~fb${}^{-1}$, 711.0~fb${}^{-1}$, 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 $D_s^{\ast +}{D}_s^{\ast +}$ are studied to search for possible resonances. No significant signals are observed, and the 90\% confidence level upper limits on the product branching fractions [$\mathcal{B}({\rm Y}(1S,2S)\to X_{cc\bar{s}\bar{s}}+anything)\times \mathcal{B}(X_{cc\bar{s}\bar{s}}\to D_s^{+}{D}_s^{+}(D_s^{\ast +}{D}_s^{\ast +}))$] in ${\rm Y}(1S,2S)$ inclusive decays and the product values of Born cross section and branching fraction [$\sigma (e^{+}{e}^{-}\to X_{cc\bar{s}\bar{s}}+anything)\times \mathcal{B}(X_{cc\bar{s}\bar{s}}\to D_s^{+}{D}_s^{+}(D_s^{\ast +}{D}_s^{\ast +}))$] in $e^{+}{e}^{-}$ collisions at $\sqrt{s}$ = 10.52~GeV, 10.58~GeV, and 10.867~GeV under different assumptions of $X_{cc\bar{s}\bar{s}}$ masses and widths are obtained.

Comments: 12 pages, 7 figures; accepted for publication as a Regular Article in Physical Review D