Doubly heavy $QQ$ tetraquarks

Abstract

With the discovery of a doubly charmed ${\Xi }_{cc}$ baryon a somewhat forgotten issue of tetraquarks containing two heavy and two light (anti) quarks, ${\mathcal{T}}_{QQ}$, triggered theorist's interest. We discuss quark model estimates of ${\mathcal{T}}_{QQ}$ masses and such objects including a model where the light sector is treated as a soliton. We show that this model has different large $N_c$ limit than other approaches.

Comments: 6 pages, 2 figures, talk at the conference Excited QCD, Schladming, Austria, January 30 - February 3, 2019. In v2 minor typos corrected, references added