The first measurements of the top- and antitop-quark differential production cross-sections and the top-quark charge asymmetry in the forward region are presented, using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 5.4 $fb^{ -1}$. The total production cross-sections of top and antitop quarks are also determined. Measurements are performed using the $\mu+b\text{ -jet}$ final state within a fiducial region defined by a $b\text{ -jet}$ $p_{ \text{ T, jet}}>50$ GeV and pseudorapidity $2.2<\eta_{ \text{ jet}}<4.0$,, with the muon from the $W$-boson decay required to have $p_{ \text{ T},\mu}>25$ GeV and pseudorapidity $2.0<\eta_{ \mu}<4.5$. The muon and $b$-jet system must satisfy $p_{ T}(\mu+\text{ jet}) > 20$ GeV. The measured integrated production cross-sections for the top and antitop quarks are $\sigma_{ t} = 0.95 \pm 0.04 \pm 0.08 \pm 0.02$ pb, $\sigma_{ \bar{ t}} = 0.81 \pm 0.03 \pm 0.07 \pm 0.02$ pb, where the first uncertainty is statistical, the second systematic, and the third accounts for the luminosity uncertainty. The top-quark charge asymmetry is measured to be $A_C^{ t} = 0.08 \pm 0.03 \pm 0.01$, where the first uncertainty is statistical and the second is systematic. These results are consistent with next-to-leading-order Standard Model predictions.
Categories: hep-ex