Discovery potential of stable and near-threshold doubly heavy tetraquarks at the LHC

TL;DR

This paper assesses the LHC's potential to discover stable and near-threshold doubly heavy tetraquarks, providing production cross section estimates and highlighting their promising detection prospects due to large branching ratios.

Contribution

It offers the first detailed estimates of production cross sections for doubly bottom and bottom-charm tetraquarks at the LHC, combining Monte Carlo simulations with experimental data.

Findings

Estimated cross section for $T^{ ext{bb}}_{[ar u ar d]}$ is about 2.4 nb.

Predicted large branching ratios enhance discovery prospects.

Provides cross section estimates for bottom-charm tetraquarks.

Abstract

We study the LHC discovery potential of the double-bottom tetraquarks $bb \bar u \bar d$, $bb \bar u \bar s$ and $bb \bar d \bar s$, the lightest of which having $J^P=1^+$, called $T^{\{bb\}}_{[\bar u \bar d]}$, $T^{\{bb\}}_{[\bar u \bar s]}$ and $T^{\{bb\}}_{[\bar d \bar s]}$, are expected to be stable against strong decays. Employing the Monte Carlo generators MadGraph5$\_$aMC@NLO and Pythia6, we simulate the process $pp\to \bar b b\bar b b$ and calculate the $b b$-diquark jet configurations, specified by the invariant mass interval $m_{bb} < M_{T^{\{bb\}}_{[\bar q \bar q']}} + \Delta M$. Estimates of $\Delta M$ from the measured product $\sigma(pp \to B_c^+ +X){\cal B}(B_c^+\to J/\psi\pi^+)$ are presented and used to to get the $b b$-diquark jet cross sections in double-bottom hadrons $\sigma(pp \to H_{\{bb\}} +X)$, where $H_{\{bb\}} $ represent tetraquarks and baryons. This is combined with the LHCb data on the fragmentation $b \to \Lambda_b$ and $b \to B$ to obtain $\sigma(pp\to T^{\{bb\}}_{[\bar u\bar d]} +X) = (2.4 ^{+0.9}_{-0.6})\ \text{nb} $, and about a half of this for the $T^{\{bb\}}_{[\bar{u}\bar{s}]}$ and $T^{\{bb\}}_{[\bar d \bar s]}$. We also present estimates of the production cross sections for the mixed bottom-charm tetraquarks, $bc \bar u \bar d$, $bc \bar u \bar s$ and $bc \bar d \bar s$, obtaining $\sigma(pp\to T^{[bc]}_{[\bar u \bar d]} +X)= (48^{+19}_{-12})\ {\rm nb}$, and the related ones having $T^{[bc]}_{[\bar u \bar s]}$ and $T^{[bc]}_{[\bar d \bar s]}$. They have excellent discovery potential at the LHC, as their branching ratios in various charge combinations of $BD_{(s)} (\gamma)$ are anticipated to be large.