Measurement of the top quark mass in the dileptonic ttbar decay channel using the Mbl, MT2, and MAOS Mblv observables

We report on a measurement of the top-quark mass ($\mathrm{M}_{\mathrm{t}}$) in the dileptonic $\mathrm{t}\overline{\mathrm{t}}$ decay channel using events selected from a data sample corresponding to an integrated luminosity of $19.7 \pm 0.5 \text{ fb}^{-1}$. The events were recorded by the CMS detector at the LHC in proton-proton collisions at $\sqrt{s} = 8$ TeV. The analysis is based on three observables whose distribution shapes are sensitive to the value of $\mathrm{M}_{\mathrm{t}}$. The $\mathrm{M}_{\mathrm{b}\ell}$ invariant mass and $\mathrm{M}_{\mathrm{T}2}^{\mathrm{bb}}$ `stransverse mass' observables are employed in a simultaneous fit to determine the value of $\mathrm{M}_{\mathrm{t}}$ and an overall jet energy scale factor (JSF). In a complementary approach, the $\mathrm{M}_{\mathrm{T}2}$-Assisted On-Shell reconstruction technique is used to construct an $\mathrm{M}_{\mathrm{b}\ell\nu}$ invariant mass observable that is combined with $\mathrm{M}_{\mathrm{T}2}^{\mathrm{bb}}$ to measure $\mathrm{M}_{\mathrm{t}}$. The shapes of the observables, along with their evolutions in $\mathrm{M}_{\mathrm{t}}$ and JSF, are modeled by a non-parametric Gaussian Process regression technique. The top-quark mass is measured to be $172.22 \pm 0.18 \text{ (stat)} \,^{+0.89}_{-0.93} \text{ (syst) GeV}$.