Weak decays of the axial-vector tetraquark $T_{bb;\bar{u} \bar{d}}^{-}$

TL;DR

This paper investigates the weak decay properties of a specific doubly-heavy axial-vector tetraquark using QCD sum rules, providing mass, decay width, and lifetime estimates to aid experimental searches.

Contribution

It offers the first calculation of the mass, decay width, and lifetime of the $T_{bb;ar{u} ar{d}}^{-}$ tetraquark, including its semileptonic decay channels, using QCD sum rule techniques.

Findings

Mass of $T_{bb;ar{u} ar{d}}^{-}$ is approximately 10035 MeV.

Full decay width is about 7.17 x 10^{-8} MeV.

Lifetime is estimated at around 9.18 femtoseconds.

Abstract

The weak decays of the axial-vector tetraquark $T_{bb;\bar{u} \bar{d}}^{-}$ to the scalar state $Z_{bc;\bar{u} \bar{d}}^{0}$ are investigated using the QCD three-point sum rule approach. In order to explore the process $T_{bb; \bar{u} \bar{d}}^{-} \to Z_{bc;\bar{u} \bar{d}}^{0}l \bar{\nu_l}$, we recalculate the spectroscopic parameters of the tetraquark $T_{bb;\bar{u} \bar{d}}^{-}$ and find the mass and coupling of the scalar four-quark system $Z_{bc;\bar{u} \bar{d}}^{0}$, which are important ingredients of calculations. The spectroscopic parameters of these tetraquarks are computed in the framework of the QCD two-point sum rule method by taking into account various condensates up to dimension ten. The mass of the $T_{bb;\bar{u} \bar{ d}}^{-}$ state is found to be $m=(10035~\pm 260)~\mathrm{MeV}$, which demonstrates that it is stable against the strong and electromagnetic decays. The full width $\Gamma$ and mean lifetime $\tau$ of $T_{bb;\bar{u} \bar{d} }^{-}$ are evaluated using its semileptonic decay channels $T_{bb; \bar{u} \bar{d}}^{-} \to Z_{bc;\bar{u} \bar{d}}^{0}l \bar{\nu_l}$, $l=e,\mu$ and $\tau$. The obtained results, $\Gamma=(7.17\pm 1.23)\times 10^{-8\ \ } \mathrm{MeV}$ and $\tau =9.18_{-1.34}^{+1.90}~\mathrm{fs}$, can be useful for experimental investigations of the doubly-heavy tetraquarks.