Graviton production through photon-quark scattering at the LHC

We have investigated real graviton emission in the Arkani-Hamed-Dimopoulos–Dvali (ADD) and Randall-Sundrum (RS) models of extra dimensions through the photoproduction process $pp\to p\gamma p\to pGqX$ at the LHC. We have considered all contributions from the subprocesses $\gamma q\to Gq$, where $q=u,d,c,s,b,\overline{u},\overline{d},\overline{c},\overline{s},\overline{b}$ quark. The constraints on model parameters of the ADD and RS models of extra dimensions have been calculated. During numerical calculations we have taken into account 3, 4, 5, and 6 large extradimensional scenarios. The constraints on RS model parameters have been calculated by considering $G\to \gamma \gamma$, $e\overline{e}$, $\mu \overline{\mu }$ decay channels of the graviton.

Figure 1

The photoproduction process $pp\to p\gamma p\to pGqX$.

Figure 2

Tree-level Feynman diagrams for the subprocess $\gamma q\to Gq$ ($q=u,d,c,s,b,\overline{u},\overline{d},\overline{c},\overline{s},\overline{b}$).

Figure 3

The total cross section of the process $pp\to p\gamma p\to pGqX$ as a function of the fundamental scale $M_D$ for various numbers of extra dimensions $\delta$. The forward detector acceptance is chosen to be $0.0015<\xi <0.5$.

Figure 4

The total cross section of the process $pp\to p\gamma p\to pGqX$ as a function of the fundamental scale $M_D$ for various numbers of extra dimensions $\delta$. The forward detector acceptance is chosen to be $0.0015<\xi <0.15$.

Figure 5

The differential cross section of the process $pp\to p\gamma p\to pGqX$ as a function of the transverse momentum of the KK tower. The number of extra dimensions is chosen to be $\delta =3$ and $M_D=5\mathrm{TeV}$. In the left panel we present the total cross section (solid line), which represents the sum of all contributions from subprocesses in (1) and cross sections including individual contributions from each subprocess with quarks. In the right panel we present similar plots but for subprocesses with antiquarks.

Figure 6

The same as Fig. 5 but for $\delta =4$.

Figure 7

The same as Fig. 5 but for $\delta =5$.

Figure 8

The same as Fig. 5 but for $\delta =6$.

Figure 9

The missing transverse momentum dependence of the cross section for the process $pp\to p\gamma p\to pGqX$ and the Standard Model background in the center-of-momentum frame of the proton-proton system. VFD acceptance is taken to be $0.0015<\xi <0.5$ and $M_D=5\mathrm{TeV}$.

Figure 10

The missing invariant mass dependence of the cross section for the process $pp\to p\gamma p\to pGqX$ and the Standard Model background in the center-of-momentum frame of the proton-proton system. VFD acceptance is taken to be $0.0015<\xi <0.5$ and $M_D=5\mathrm{TeV}$.

Figure 11

The angular distribution of the graviton in the center-of-momentum frame of the proton-proton system. $\theta$ is the angle between the outgoing graviton and the incoming photon emitting intact proton. RS model parameters are chosen to be $\beta =0.05$ and $m_G=1\mathrm{TeV}$. In the left panel we present the total cross section (solid line) which represents the sum of all contributions from subprocesses in (1) and cross sections including individual contributions from each subprocess with quarks. In the right panel we present similar plots but for subprocesses with antiquarks.

Figure 12

The 95% C.L. limits in the RS parameter space for an integrated luminosity of $200{\mathrm{fb}}^{-1}$. The excluded regions are defined by the area above the curves. $G\to \gamma \gamma ,e\overline{e},\mu \overline{\mu }$ decay channels with a total branching ratio of 8% are considered.