Probe of extra dimensions in $\gamma q\to \gamma q$ at the LHC

We have examined TeV scale effects of extra spatial dimensions through the processes $\gamma q\to \gamma q$, where $q=u$, $d$, $c$, $s$, $b$, $\overline{u}$, $\overline{d}$, $\overline{c}$, $\overline{s}$, $\overline{b}$. These processes have been treated in a photon-proton collision via the main reaction $pp\to p\gamma p\to p\gamma qX$ at the LHC. We have employed the equivalent photon approximation for incoming photon beams and performed statistical analysis for various forward detector acceptances.

Figure 1

Schematic diagram for the reaction $pp\to p\gamma p\to p\gamma qX$.

Figure 2

Tree-level Feynman diagrams for the subprocess $\gamma q\to \gamma q$ ($q=u$, $d$, $c$, $s$, $b$, $\overline{u}$, $\overline{d}$, $\overline{c}$, $\overline{s}$, $\overline{b}$) in the presence of Kaluza-Klein graviton mediation.

Figure 3

The 95% C.L. lower bounds for ${\Lambda }_T$ as a function of integrated LHC luminosity for forward detector acceptance regions $0.0015<\xi <0.5$ (left panel) and $0.0015<\xi <0.15$ (right panel). Legends are for various values of the virtuality of the deep inelastic scattering.

Figure 4

The 95% C.L. lower bounds for ${\Lambda }_T$ as a function of integrated LHC luminosity for forward detector acceptance regions $0.1<\xi <0.5$ (left panel) and $0.1<\xi <0.15$ (right panel). Legends are for various values of the virtuality of the deep inelastic scattering.

Figure 5

Limits in the $\beta -m_G$ plane for an integrated luminosity of $200{\mathrm{fb}}^{-1}$. The regions above the curves are excluded at 95% C.L. The virtuality of the deep inelastic scattering is taken to be $Q^2=(5M_Z{)}^2$, where $M_Z$ is the mass of the $Z$ boson.