Masses of the doubly heavy tetraquarks in a constituent quark model

TL;DR

This study uses a constituent quark model to calculate the masses of doubly heavy tetraquarks, revealing less binding than simplified models and identifying specific bound states like $T_{bb}(udar{b}ar{b})$ and $T_{bb}(usar{b}ar{b})$.

Contribution

It provides a detailed constituent quark model analysis of doubly heavy tetraquark masses with constrained parameters, improving upon previous less precise models.

Findings

$T_{bb}(udar{b}ar{b})$ is bound by 120.56 MeV.

$T_{bb}(usar{b}ar{b})$ is bound by 7.3 MeV.

Full calculations show less binding compared to simplified models.

Abstract

We perform a constituent quark model analysis for the masses of the doubly heavy tetraquark states $T_{QQ}$ after we fix the parameters to fit the masses of the newly observed $\Xi_{cc}^{++}$ and hadrons involving heavy quarks relevant to the stability of these states. We investigate in detail how the relative distances between quark pairs vary as we change the quark content and how they affect the various contributions to the total tetraquark masses. We also find that our full calculations give in general less binding compared to simplified quark model calculations that treat quark dynamics inside the tetraquark the same as that inside a baryon. We trace the main origin to be the differences in the number of relative kinetic energies which increases as one goes from meson, baryon and tetraquarks. We also compare our new results with previous works using less constrained parameters and find that the tetraquark state $T_{bb}(ud\bar{b}\bar{b})$ and $T_{bb}(us\bar{b}\bar{b})$ are bound by 120.56 MeV and 7.3 MeV respectively.