Doubly heavy baryons at the LHC

The theoretical analysis of production, lifetime, and decays of doubly heavy baryons is presented. The lifetime of ${\mathrm{\Xi }}_{cc}^{++}$ baryons recently measured by the LHCb Collaboration is used to estimate the lifetimes of other doubly heavy baryons. The production and the possibility of observation of ${\mathrm{\Xi }}_{bc}$ baryons at the LHC are discussed.

Figure 1

The example of analogous diagrams for $(Q_1{\overline{Q}}_2)$-quarkonium production and for $(Q_1{Q}_{2}q)$-baryon production.

Figure 2

${\mathrm{\Xi }}_{bc}$ $p_T$ distribution vs. $B_c$ $p_T$ distribution for $\sqrt{s_{gg}}=30\mathrm{GeV}$ and $\sqrt{s_{gg}}=60\mathrm{GeV}$, respectively. The same quark mass values are used for both estimations: $m_c=1.5\mathrm{GeV}$ and $m_b=4.8\mathrm{GeV}$. Also, for the convenience of comparison, we put $|R_{B_c}(0){|}^2$ and $|R_{[bc{]}_{\overline{3}}}(0){|}^2$ equal.

Figure 3

The ratio of production yields of ${\mathrm{\Xi }}_{bc}$ and $B_c$ for hadronic interaction at $\sqrt{s}=13\mathrm{TeV}$ in units of $|R_{[bc{]}_{\overline{3}}}(0){|}^2/|R_{B_c}(0){|}^2$ for the similar quark masses [$m_b=4.8\mathrm{GeV}$, $m_c=1.5\mathrm{GeV}$ (solid curve)] and for the different quark masses [$m_b=4.8\mathrm{GeV}$ and $m_c=1.5\mathrm{GeV}$ for $B_c$ production, and $m_b=4.9\mathrm{GeV}$ and $m_c=1.7\mathrm{GeV}$ for ${\mathrm{\Xi }}_{bc}$ production (dashed curve)]. The CT14LL parametrization [9] is used for PDFs.

Figure 4

Feynman diagrams for ${\mathrm{\Xi }}_{cc}$ baryon decay: (a) spectator mechanism, (b) weak scattering and (c,d) Pauli interference.

Figure 5

Lifetimes in ps for ${\mathrm{\Xi }}_{cc}^{++}$ (solid black curve), ${\mathrm{\Xi }}_{cc}^{+}$ (blue dashed curve) and ${\mathrm{\Omega }}_{cc}^{+}$ (red dotted curve) as a function of the model parameters. The results of [35] are shown by dots.

Figure 6

The partial widths for different operators for doubly charmed baryons (in ${\mathrm{ps}}^{-1}$): operators of dimensions 3 and 5 corresponding to the spectator mechanism (dashed blue curve), operators of dimension 6 corresponding to the weak scattering and Pauli interference (red dotted curve), and the total width (black solid curve). The dots correspond to the predictions of [35].

Figure 7

Lifetimes in ps for ${\mathrm{\Xi }}_{bc}^{+}$ (solid black curve), ${\mathrm{\Xi }}_{bc}^0$ (blue dashed curve) and ${\mathrm{\Omega }}_{bc}^0$ (red dotted curve) as a function of the model parameters. The results of [35] are shown by dots.

Figure 8

The partial widths for different operators for $bc$ baryons (in ${\mathrm{ps}}^{-1}$): operators of dimensions 3 and 5 corresponding to the spectator mechanism (dashed blue curve); operators of dimension 6 corresponding to the weak scattering and Pauli interference (red dotted and black dashed-dotted curves, respectively); and the total width (black solid curve). The dots correspond to the predictions of [35].

Figure 9

Decay widths for $bb$ baryons. Designations as in Fig. 6.

Figure 10

Lifetimes in ps for ${\mathrm{\Xi }}_{bb}^0$ (solid black curve), ${\mathrm{\Xi }}_{bb}^{-}$ (blue dashed curve) and ${\mathrm{\Omega }}_{bb}^{-}$ (red dotted curve) as a function of the model parameters. The results of [35] are shown by dots.