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

We study the LHC discovery potential of the double-bottom tetraquarks $bb\overline{u}\overline{d}$, $bb\overline{u}\overline{s}$ and $bb\overline{d}\overline{s}$, the lightest of which having $J^P=1^{+}$, called $T_{\left[\overline{u}\overline{d}\right]}^{\left\{bb\right\}}$, $T_{\left[\overline{u}\overline{s}\right]}^{\left\{bb\right\}}$ and $T_{\left[\overline{d}\overline{s}\right]}^{\left\{bb\right\}}$, are expected to be stable against strong decays. Employing the Monte Carlo generators MadGraph5_aMC@NLO and Pythia6, we simulate the process $pp\to \overline{b}b\overline{b}b+X$ and calculate the bb-diquark jet configurations, specified by the invariant mass interval $M_{bb}<M_{T_{\left[\overline{q}{\overline{q}}^{\prime }\right]}^{\left\{bb\right\}}}+\Delta M$. Estimates of ΔM from the measured product $\sigma (pp\to B_c^{+}+X)B(B_c^{+}\to J/\psi {\pi }^{+})$ are presented and used to get the bb-diquark jet cross sections in double-bottom hadrons $\sigma (pp\to H_{\left\{bb\right\}}+X)$, where $H_{\left\{bb\right\}}$ represent tetraquarks and baryons. This is combined with the LHCb data on the fragmentation $b\to {\Lambda }_b$ and $b\to B$ to obtain $\sigma (pp\to T_{\left[\overline{u}\overline{d}\right]}^{\left\{bb\right\}}+X)=\left({2.8}_{-0.7}^{+1.0}\right)\text{nb}$ at $\sqrt{s}=13$ TeV, and about a quarter of this for the $T_{\left[\overline{u}\overline{s}\right]}^{\left\{bb\right\}}$ and $T_{\left[\overline{d}\overline{s}\right]}^{\left\{bb\right\}}$, each. We also present estimates of the production cross sections for the mixed bottom-charm tetraquarks, $bc\overline{u}\overline{d}$, $bc\overline{u}\overline{s}$ and $bc\overline{d}\overline{s}$, obtaining $\sigma (pp\to T_{\left[\overline{u}\overline{d}\right]}^{\left[bc\right]}+X)=\left({103}_{-25}^{+39}\right)\text{nb}$ at $\sqrt{s}=13$ TeV, and the related ones having $T_{\left[\overline{u}\overline{s}\right]}^{\left[bc\right]}$ and $T_{\left[\overline{d}\overline{s}\right]}^{\left[bc\right]}$. They have excellent discovery potential at the LHC, as their branching ratios in various charge combinations of $B{D}_{\left(s\right)}\left(\gamma \right)$ are anticipated to be large.