Volume 340 - The 39th International Conference on High Energy Physics (ICHEP2018) - Parallel: Strong Interactions and Hadron Physics
Lattice Predictions for Bound Heavy Tetraquarks
A. Francis,* R.J. Hudspith, R. Lewis, K. Maltman
*corresponding author
Full text: pdf
Published on: August 02, 2019
Abstract
We investigate the possibility of doubly heavy $qq^\prime \bar Q \bar Q^\prime$ tetraquark bound states using $n_f=2+1$ lattice QCD with pion masses $\simeq 164$, $299$ and $415$ MeV. Two types of lattice interpolating operator are chosen, reflecting first diquark-antidiquark and second meson-meson structure. Performing variational analyses using these operators and their mixings, we determine the ground and first excited states from the lattice correlators. Using non-relativistic QCD to simulate the bottom quarks and the Tsukuba formulation of relativistic heavy quarks for charm quarks, we study the $ud\bar b \bar b$, $\ell s\bar b \bar b$ as well as $ud\bar c \bar b$, channels with $\ell=u,d$. In the case of the $ud\bar b \bar b$ and $\ell s\bar b \bar b$ channels unambiguous signals for $J^P=1^+$ tetraquarks are found with binding energies $189(10)$ and $98(7)$ MeV below the corresponding free two-meson thresholds at the physical point. These tetraquarks are therefore not only strong-interaction, but also electromagnetic-interaction stable, and can decay only weakly. So far these are the first exotic hadrons predicted to have this feature. Further evidence for binding is found in the $ud\bar c \bar b$ channel, where the binding energy broadly straddles the electromagnetic stability threshold.
We also study the dependence of the tetraquark binding on heavy quark mass by considering the channels $ud\bar b' \bar b'$, $\ell s\bar b' \bar b'$ as well as $ud\bar b' \bar b$, $\ell s\bar b' \bar b$ involving a heavy $b'$ quark with mass between roughly $0.6$ and $6.3$ times the physical $b$ quark mass. The observed mass dependence of these four flavor channels is shown to follow closely a phenomenological form expected on simple physical grounds.
DOI: https://doi.org/10.22323/1.340.0257
How to cite

Metadata are provided both in "article" format (very similar to INSPIRE) as this helps creating very compact bibliographies which can be beneficial to authors and readers, and in "proceeding" format which is more detailed and complete.

Open Access
Copyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.