XXVIII International Workshop on Deep-Inelastic Scattering and Related Subjects

Rare two-body decays of the top quark into a bottom meson plus an up or charm quark

15 Apr 2021, 08:41

18m

Virtual (Stony Brook, NY)

Contributed Talk QCD with Heavy Flavors and Hadronic Final States QCD with Heavy Flavors and Hadronic Final States

Speaker

David d'Enterria (CERN)

Description

Rare two-body decays of the top quark into a neutral bottom-quark meson plus an up- or charm-quark: $t\to {\bar{B}}^0+u,c$; $t\to {\bar{B}}_s^0+c,u$; and $t\to \mathrm{{\rm Y}}(nS)+c,u$, are studied for the first time. The corresponding partials widths are computed at leading order in the non-relativistic QCD framework. The sums of all two-body branching ratios amount to $\mathcal{B}(t\to {\bar{B}}^0+\mathrm{j}\mathrm{e}\mathrm{t})\approx \mathcal{B}(t\to {\bar{B}}_s^0+\mathrm{j}\mathrm{e}\mathrm{t})\approx 4.2\cdot {10}^{-5}$ and $\mathcal{B}(t\to \mathrm{{\rm Y}}(nS)+\mathrm{j}\mathrm{e}\mathrm{t})\approx 2\cdot {10}^{-9}$, respectively. The feasibility to observe the $t\to {\bar{B}}_{(s)}^0+\mathrm{j}\mathrm{e}\mathrm{t}$ decay is estimated in top-pair events produced in proton-proton collisions at $\sqrt{s}=14,100$ TeV at the LHC and FCC, respectively. Combining many exclusive hadronic ${\bar{B}}_{(s)}^0$ decays, with $J/\psi$ or $D^{0,\pm }$ final states, about 50 (16\,000) events are expected in 3 (20) ab${}^{-1}$ of integrated luminosity at the LHC (FCC), after ty
pical selection criteria, acceptance, and efficiency losses. An observation of the two-body top-quark decay can also be achieved in the interesting $t\to b(\mathrm{j}\mathrm{e}\mathrm{t})+\mathrm{c}(\mathrm{j}\mathrm{e}\mathrm{t})$ dijet final state, where t
he ${\bar{B}}_{(s)}^0$ decay products are reconstructed as a jet, with 5\,300 and 1.4 million signal events above backgrounds expected after selection criteria at the LHC and FCC, respectively. Such unique final states provide a new direct method to precisely measure the top-quark mass via simple 2-body invariant mass analyses.

Presentation materials

dde_top_2body_decay_DIS_apr2021.pdf

Youtube Link