Top-quark pair production cross sections at NNLO+NNLL in pPb collisions at $\sqrt{s_{NN}}$ = 8.16 TeV

Total and fiducial top pair ($t\bar{t}$) production cross sections in proton-lead (pPb) collisions at $\sqrt{s_{NN}}$ = 8.16 TeV are computed at next-to-next-to-leading-order (NNLO) accuracy including next-to-next-to-leading-log (NNLL) gluon resummation, using the CT14 and CT10 proton parton distribution functions (PDF), and the EPPS16 and EPS09 nuclear PDF parametrizations for the lead ion. The total cross sections amount to $\sigma(pPb\to t\bar{t}+X) = 59.0 \pm 5.3$(CT14+EPPS16)$\,^{+1.6}_{-2.1}$(scale) nb, and $57.5 \pm \,^{+4.3}_{-3.3}$(CT10+EPS09)$\,^{+1.5}_{-2.0}$(scale) nb, with small modifications with respect to the result computed using the free proton PDF alone. The normalized ratio of pPb to pp cross sections (nuclear modification factor) is $R_{pPb} = 1.04 \,^{\pm 0.07(EPPS16)}_{\pm0.03(EPS09)}$. In the lepton+jets decay mode, $t\bar{t} \to b\bar{b} W(\ell\nu) W(q\bar{q}')$, one expects $\sim$600 $t\bar{t}$ events in the 180 nb$^{-1}$ integrated luminosity collected in pPb collisions at the LHC so far, after typical acceptance and efficiency losses. Differential cross sections at NLO accuracy are presented as a function of transverse momentum and rapidity of the top quarks, and of their decay b-jets and isolated leptons.