# First observation of top quark production in the forward region

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## Abstract

Top quark production in the forward region in proton-proton collisions is observed for the first time. The $W + b$ final state with $W\to\mu\nu$ is reconstructed using muons with a transverse momentum, $p_{\rm T}$, larger than 25 GeV in the pseudorapidity range $2.0<\eta<4.5$. The $b$ jets are required to have $50 < p_{\rm T} < 100$ GeV and $2.2 < \eta < 4.2$, while the transverse component of the sum of the muon and $b$-jet momenta must satisfy $p_{\rm T} > 20$ GeV. The results are based on data corresponding to integrated luminosities of 1.0 and $2.0$ fb$^{-1}$ collected at center-of-mass energies of 7 and 8 TeV by LHCb. The inclusive top quark production cross-sections in the fiducial region are $\sigma({\rm top})[7\rm{TeV}] = 239\pm53({\rm stat})\pm33({\rm syst})\pm24({\rm theory}) {\rm fb}$ and $\sigma({\rm top})[8\rm{TeV}] = 289\pm43({\rm stat})\pm40({\rm syst})\pm29({\rm theory}) {\rm fb}$. These results, along with the observed differential yields and charge asymmetries, are in agreement with next-to-leading order Standard Model predictions.

## Figures and captions

 Distribution of $p_{\rm T}$ (\mu)/ $p_{\rm T} (j_\mu)$ with fit overlaid for all $W+$jet candidates. Fig1.pdf [13 KiB] HiDef png [105 KiB] Thumbnail [92 KiB] *.C file Results for the inclusive $W+$jet yield (left) and charge asymmetry (right) versus $p_{\rm T} (\mu+j)$ compared to SM predictions at NLO obtained using MCFM. The data error bars are smaller than the marker size, the SM uncertainties are highly correlated across $p_{\rm T} (\mu+j)$ bins. Fig2a.pdf [13 KiB] HiDef png [92 KiB] Thumbnail [80 KiB] *.C file Fig2b.pdf [13 KiB] HiDef png [89 KiB] Thumbnail [82 KiB] *.C file Results for $W + c$ compared to SM predictions at NLO obtained using MCFM. Fig3.pdf [13 KiB] HiDef png [82 KiB] Thumbnail [72 KiB] *.C file Distribution of $p_{\rm T}$ (\mu)/ $p_{\rm T} (j_\mu)$ with fit overlaid for all $W + b$ candidates. Fig4.pdf [13 KiB] HiDef png [103 KiB] Thumbnail [90 KiB] *.C file Results for the $W + b$ yield (left) and charge asymmetry (right) versus $p_{\rm T} (\mu+b)$ compared to SM predictions obtained at NLO using MCFM. Fig5a.pdf [13 KiB] HiDef png [88 KiB] Thumbnail [77 KiB] *.C file Fig5b.pdf [13 KiB] HiDef png [101 KiB] Thumbnail [92 KiB] *.C file Distribution of $p_{\rm T}(\mu)/p_{\rm T}(j_{\mu})$ with fit overlaid for all $W + c$ candidates. Fig1s.pdf [13 KiB] HiDef png [100 KiB] Thumbnail [88 KiB] *.C file Animated gif made out of all figures. PAPER-2015-022.gif Thumbnail

## Tables and captions

 Relative systematic uncertainties. The symbol $\dagger$ denotes an uncertainty that only applies to the cross-section measurement and not the significance determination. Only the luminosity uncertainty depends on $\sqrt{s}$: 2% at 7 TeV and 1% at 8 TeV. Table_1.pdf [54 KiB] HiDef png [131 KiB] Thumbnail [57 KiB] tex code

Created on 11 July 2020.