Probe Anomalous $tqγ$ couplings through Single Top Photoproduction at the LHC

Abstract

In this work we study the constraints on the anomalous $tqγ$ ($q=u$, $c$) couplings by photon-produced leading single top production and single top jet associated production through the main reaction $pp\rightarrow pγp\rightarrow pt\rightarrow pW(\rightarrow\ell ν_\ell) b+X$ and $pp\rightarrow pγp\rightarrow ptj\rightarrow pW(\rightarrow\ell ν_\ell) bj+X$ assuming a typical LHC multipurpose forward detectors in a model independent effective lagrangian approach. Our results show that: for the typical detector acceptance $0.0015<ξ_1<0.5$, $0.1<ξ_2<0.5$ and $0.0015<ξ_3<0.15$ with a luminosity of 2 $\rm{fb}^{-1}$, the lower bounds of $κ_{tqγ}$ through leading single top channel (single top jet channel) are 0.0096 (0.0115), 0.0162 (0.0152) and 0.0098 (0.0122), respectively, correspond to $\rm{Br}(t\rightarrow qγ)\sim 3\times 10^{-5}$. With a luminosity of 200 $\rm{fb}^{-1}$, the lower bounds of $κ_{tqγ}$ are 0.0031 (0.0034), 0.0051 (0.0047) and 0.0031(0.0038), respectively, correspond to $\rm{Br}(t\rightarrow qγ)\sim 4\times 10^{-6}$. We conclude that both channels can be used to detect such anomalous $tqγ$ couplings and the detection sensitivity on $κ_{tqγ}$ can be improved.

37pages, 10 figures, 6 tables, to appear in Nuclear Physics B