Abstract
Motivated by the LHCb's very recent observation of exotic $X_{0}(2900)$ in the $B^{+}\rightarrow D^{+}D^{-}K^{+}$ process, for which could be a good open charm $ud\bar{c}\bar{s}$ tetraquark candidate, we endeavor to investigate its possibility by means of QCD sum rules. In technique, four configurations of interpolating currents with $J^{P}=0^{+}$ are studied for the $ud\bar{c}\bar{s}$ tetraquark state. In the end, mass values are calculated to be $2.76^{+0.16}_{-0.23}~\mbox{GeV}$ for the axial vector diquark-axial vector antidiquark configuration and $2.75^{+0.15}_{-0.24}~\mbox{GeV}$ for the scalar diquark-scalar antidiquark configuration, both of which are consistent with the experimental data $2.866\pm0.007\pm0.002~\mbox{GeV}$ of $X_{0}(2900)$ in view of the uncertainty. These results support that $X_{0}(2900)$ could be a $0^{+}$ tetraquark state with open charm flavor.
Highlights
In the past decades, the so-called X, Y, and Z new hadrons have attracted wide attentions and some of them were assigned to be possible exotic states
Complying with the usual treatment of QCD sum rules, a tetraquark state can be represented by an interpolating current with the diquark-antidiquark configuration
The final results for the axial vector diquark-axial vector antidiquark and the scalar diquark-scalar antidiquark cases both agree with the experimental data of X0ð2900Þ viewing the uncertainty of final results, which supports that X0ð2900Þ could be a 0þ udcstetraquark state with the axial vector diquark-axial vector antidiquark or the scalar diquark-scalar antidiquark configuration
Summary
The so-called X, Y, and Z new hadrons have attracted wide attentions and some of them were assigned to be possible exotic states (for recent reviews, e.g., see [1,2,3] and references therein). Complying with the usual treatment of QCD sum rules, a tetraquark state can be represented by an interpolating current with the diquark-antidiquark configuration (e.g., see the review [12] and references therein). For the present 0þ udcstetraquark state, one can construct its different configuration currents with 0þ composed of an ud-diquark and a cs-antidiquark, taking into account that uTa Cγ5db as a 0þ scalar diquark, uTa Cdb as a 0− pseudoscalar diquark, uTa Cγμdb as a 1þ axial vector diquark, uTa Cγ5γμdb as a 1− vector diquark, and likewise for the csantidiquark. The spectral density ρ does not contain the hqqi or hgqσ · Gqi condensate
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