Production mechanism of doubly charmed exotic mesons $T_{cc}$

TL;DR

This paper models the production mechanisms of doubly charmed tetraquark mesons using a coupled-channel approach respecting symmetries, predicting multiple bound and resonance states with specific quantum numbers.

Contribution

It introduces a coupled-channel formalism with effective Lagrangians respecting key symmetries to predict tetraquark states and their properties.

Findings

Identifies three positive-parity and one negative-parity tetraquark states.

Predicts bound states in $DD^*$ channels and a resonance in $D^*D^*$.

Most stable state persists across cutoff variations.

Abstract

We investigate the production mechanism for doubly charmed tetraquark mesons within a coupled-channel formalism. The two-body Feynman kernel amplitudes are constructed using effective Lagrangians that respect heavy quark symmetry, chiral symmetry, SU(3) flavor symmetry, and hidden local symmetry. The fully off-shell coupled scattering equations are solved within the Blankenbecler-Sugar (BbS) reduction scheme. We find three positive-parity and one negative-parity tetraquark states with total spin $J=1$. Among them, two positive-parity states appear as bound states in the isoscalar and isovector $DD^*$ channels, while another appears as a resonance in the $D^*D^*$ channel. A negative-parity resonance is also predicted in the isoscalar channel. We analyze the coupling strengths of these tetraquark states to various channels. The dependence of the results on the reduced cutoff mass $\Lambda_0$ is examined. The most significant tetraquark state remains stable within the range of $\Lambda_0=(600-700)$ MeV.