Matthias Saimpert

Light-by-light scattering with intact protons at the LHC: from standard model to new physics

A bstractWe discuss the discovery potential of light-by-light scattering at the Large Hadron Collider (LHC), induced by the Standard Model (SM) and by new exotic charged particles. Our simulation relies on intact proton detection in the planned forward detectors of CMS and ATLAS. The full four-photon amplitudes generated by any electrically charged particles of spins 1/2 and 1, including the SM processes involving loops of leptons, quarks and W bosons are implemented in the Forward Physics Monte Carlo generator. Our method provides model-independent bounds on massive charged particles, only parametrized by the spin, mass and “effective charge” Qeff of the new particle. We find that a new charged vector (fermion) with Qeff = 4 can be discovered up to m = 700 GeV (m = 370 GeV) with an integrated luminosity of 300 fb−1 at the LHC. We also discuss the sensitivities to neutral particles such as a strongly-interacting heavy dilaton and warped Kaluza-Klein gravitons, whose effects could be discovered for masses in the multi-TeV range.

Probing the Pomeron structure using dijets and gamma plus jet events at the LHC

We consider hard diffractive events in proton-proton collisions at the LHC, in which both protons escape the collision intact. In such double Pomeron exchange processes, we propose to measure dijet ...

Exploring the Pomeron structure at the LHC

We present some physics topics that will allow us to constrain the Pomeron structure at the LHC in terms of gluon and quark densities using the dijet and γ+jet events and tagged protons in AFP (ATLAS) and CMS-TOTEM. We also discuss the possibility to test the BFKL dynamics using jet-gap-jet events.

Constraining the pomeron structure using LHC data

We present here potential measurements at the LHC that can constrain the Pomeron, a colorless object which is exchanged during hard diffractive events in proton-proton collisions. So far, the Pomeron structure in terms of quarks and gluons has been extracted from QCD fits using HERA and Tevatron data. The LHC allows us to probe its structure in a completely new kinematical domain. The measurements which are discussed in this report use double Pomeron exchange (DPE) dijet and photon-jet final state processes, in which both protons escape the collision intact. Proton tagging is assumed and event generation is performed using the Forward Physics Monte Carlo (FPMC), a generator that has been designed to study forward physics, especially at the LHC.