Abstract
The doubly charmed exotic state ${T}_{cc}$ recently discovered by the LHCb Collaboration could well be a $D{D}^{*}$ molecular state long predicted in various theoretical models, in particular, the $D{D}^{*}$ isoscalar axial vector molecular state predicted in the one-boson-exchange model. In this work, we study the $DD{D}^{*}$ system in the Gaussian expansion method with the $D{D}^{*}$ interaction derived from the one-boson-exchange model and constrained by the precise binding energy of $273\ifmmode\pm\else\textpm\fi{}63\text{ }\text{ }\mathrm{keV}$ of ${T}_{cc}$ with respect to the ${D}^{*+}{D}^{0}$ threshold. We show the existence of a $DD{D}^{*}$ state with a binding energy of a few hundred keV, isospin $1/2$, and spin-parity ${1}^{\ensuremath{-}}$. Its main decay modes are $DDD\ensuremath{\pi}$ and $DDD\ensuremath{\gamma}$. The existence of such a state could in principle be confirmed with the upcoming LHC data and will unambiguously determine the nature of the ${T}_{cc}^{+}$ state and of the many exotic states of similar kind, thus deepening our understanding of the nonperturbative strong interaction.
Highlights
Starting from the discovery of DÃs0ð2317Þ [1] and Xð3872Þ [2] in 2003, a large number of the so-called exotic states that do not fit into the conventional quark model have been observed, which have led to intensive studies both theoretically and experimentally [3,4,5,6,7,8]
The measured binding energy and preferred quantum numbers of the Tcc state are in very good agreement with our predictions based on the one-boson-exchange (OBE) model [18,22], qualifies as a DDÃ molecule with IðJPÞ 1⁄4 0ð1þÞ
As the Tcc state is found about 0.3 MeV below the DÃþD0 threshold and the difference between the thresholds of DþDÃ0 and DÃþD0 is 1.41 MeV, we study three different binding energy scenarios for the DDÃ
Summary
Starting from the discovery of DÃs0ð2317Þ [1] and Xð3872Þ [2] in 2003, a large number of the so-called exotic states that do not fit into the conventional quark model have been observed, which have led to intensive studies both theoretically and experimentally [3,4,5,6,7,8]. Breit-Wigner parametrization [11], while the mass and decay width change to δ 1⁄4 360 Æ 40þ−04 keV and Γ 1⁄4 48 Æ 2þ−104 keV in a unitarized three-body Breit-Wigner amplitude model [12] Such a doubly charmed state has long been anticipated theoretically [13,14,15,16,17,18,19,20,21,22,23,24], it has remained elusive experimentally until now. In a series of recent studies [29,30,31,32,33,34,35,36,37,38], we argued that one way to check the molecular nature of certain exotic hadrons is to search for existence of multihadron molecules built from the same constituents, in the way that atomic nuclei are bound states of multinucleons.. With the latest experimental measurements [11,12], we fix the DDÃ interaction provided by the timehonored OBE model, and study the DDDÃ system using the Gaussian expansion method
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