Newly observed exotic doubly charmed meson

In this work, we treat the newly observed doubly charmed four-quark state ${T}_{cc}^{+}$ as an axial-vector tetraquark with content $cc\stackrel{‾}{u}\stackrel{‾}{d}$, and calculate its spectroscopic parameters and width. The mass and current coupling of the tetraquark ${T}_{cc}^{+}$ are found by means of the QCD two-point sum rule method by taking into account quark, gluon and mixed condensates up to dimension 10. The width of the ${T}_{cc}^{+}$ is evaluated using partial widths of decay processes ${T}_{cc}^{+}\to \stackrel{˜}{T}{\pi }^{0}$ and ${T}_{cc}^{+}\to {T}_{cc;\stackrel{‾}{u}\stackrel{‾}{u}}^{0}{\pi }^{+}$, where $\stackrel{˜}{T}=cc\stackrel{‾}{u}\stackrel{‾}{d}$ and ${T}_{cc;\stackrel{‾}{u}\stackrel{‾}{u}}^{0}$ are scalar tetraquarks. To compute the partial width of the first process, we apply the QCD three-point sum rule approach and exact numerical value of the strong coupling g that corresponds to the vertex ${T}_{cc}^{+}\stackrel{˜}{T}{\pi }^{0}$. The width of the second decay is estimated using isospin symmetry and the prediction obtained for the first channel. Our results for the mass $m=\left(3868\phantom{\rule{0.25em}{0ex}}±124\right)\phantom{\rule{0.25em}{0ex}}\text{MeV}$ and width $\Gamma =\left(489±92\right)\phantom{\rule{0.25em}{0ex}}\text{keV}$ of the tetraquark ${T}_{cc}^{+}$ are in a nice agreement with recent measurements of the LHCb collaboration.