Central Exclusive Production at Hadron Colliders

Group members: James Stirling

exclusive hard diffractive process

We study exclusive ('hard diffractive') processes pp → X pp at the Tevatron and LHC, where X is a heavy colour-singlet particle or final state. This can be an important source of (SM and SUSY) Higgs bosons and other exotic new particles at the LHC. The theoretical formalism is, however, not as rigorously developed as for standard inclusive hard scattering, and therefore benchmarking with Tevatron, RHIC and early LHC data is important. We are currently interested in the final states X = χc, χb, γγ and light meson pairs, working in collaboration with Valery Khoze (IPPP, Durham) and Misha Ryskin (Petersburg Nuclear Physics Institute, St. Petersburg). We have developed a publicly available Monte Carlo event generator, SuperCHIC, for simulating central exclusive J/ψ, Υ, γγ, χ(c,b), η(c,b) and meson pair (ππ, ηη, η'η'...) production at the Tevatron, RHIC and LHC.

We have also recently begun looking, in collaboration with Steve Kom (Liverpool) and Kazuki Sakurai (DESY), at methods for extracting the masses of new invisible particles (not seen in the detector) when they are created by (photon-mediated) CEP. These particles are characteristically produced in various BSM scenarios, such as SUSY and models with extra dimensions, and are potential dark matter candidates. With this process in mind, we have developed the PHOCEP Monte Carlo generator for the two-photon exclusive production of pairs of generic (scalar, fermion or boson) particles.

For further information, see for example arXiv:1005.0695, arXiv:1105.1626 and arXiv:1110.4320.