The ATLAS Forward Physics Project

We describe the main components of the ATLAS Forward Physics project, namely the movable beam pipe, the tracking and timing detectors which allow to detect intact protons in the final state at the LHC. The position detector is composed on 6 layers of 3D silicon detectors readout by FE-I4 chips developped for ATLAS. The fast timing detector is built from a quartz-based Cerenkov detector coupled to a microchannel plate photomultiplier tube, followed by the electronic elements that amplify, measure, and record the time of the event along with a stabilized reference clock signal, ensuring a time resolution of 10-15 picoseconds.Comment: Talk given at the 2012 Nuclear Science Symposium, IEEE, October 29 - November 3, Anaheim, US

Testing Pomeron flavour symmetry with diffractive W charge asymmetry

This study focuses on hard diffractive events produced in proton-proton collision at LHC exhibiting one intact proton in the final state which can be tagged by forward detectors. We report prospective results on the W boson charge asymmetry measured for such events, which allow to constrain the quark diffractive density functions in the Pomeron.Comment: 17 pages, 8 figures, Submitted to JHE

W+W−W^+ W^- pair production in proton-proton collisions: small missing terms

$W^+ W^-$ production is one of the golden channels for testing the Standard Model as well for searches beyond the Standard Model. We discuss many new subleading processes for inclusive production of $W^+ W^-$ pairs generally not included in the litterature so far. We focus mainly on photon-photon induced processes. We include elastic-elastic, elastic-inelastic, inelastic-elastic and inelastic-inelastic contributions. We also calculate the contributions with resolved photons including the partonic substructure of the virtual photon. Predictions for the total cross section and differential distributions in $W$- boson rapidity and transverse momentum as well as $WW$ invariant mass are presented. The $\gamma \gamma$ components only constitute about 1-2 \% of the inclusive $W^+ W^-$ cross section but increases up to about 10 \% at large $W^{\pm}$ transverse momenta, and are even comparable to the dominant $q \bar q$ component at large $M_{WW}$, i.e. are much larger than the $g g \to W^+ W^-$ one.Comment: 26 pages, 17 figure and 1 table. arXiv admin note: substantial text overlap with arXiv:1309.720

Measuring the diphoton coupling of a 750 GeV resonance

A slight excess has been observed in the first data of photon-photon events at the 13 TeV LHC, that might be interpreted has a hint of physics beyond the Standard Model. We show that a completely model-independent measurement of the photon-photon coupling of a putative 750 GeV resonance will be possible using the forward proton detectors scheduled at ATLAS and CMS.Comment: v2: version published in PR

Scattering Light by Light at 750 GeV at the LHC

We consider the possibility that the diphoton excess at 750 GeV is caused by a new scalar resonance produced in photon fusion. This scenario is parametrised by only one relevant effective couplings and is thus minimal. We show that this setup can reproduce both the production rate and width of the resonance, and is not in conflict with the 8 TeV limits on the diphoton cross section. The scenario also predicts event rates for $WW$, $ZZ$, $Z\gamma$ final states. We suggest to perform precision measurements by studying light-by-light scattering with intact protons detected in forward detectors. We construct a simple model that shows that the required couplings can be achieved with new vectorlike, uncolored fermions (with a strong Yukawa coupling to the resonance) which may also account for the required width.Comment: 6 pages, minor changes, references added. Matches PRD versio

Exclusive diffractive Higgs and jet production at the LHC

The implementation of exclusive diffractive production of Higgs boson and dijets in the FPMC (Forward Physics Monte Carlo) framework is presented following the models by Khoze, Martin, Ryskin and Cudell, Dechambre, Hernandez and Ivanov. The predictions of the models are compared to the CDF measurement of exclusive jets and the uncertainties on the Higgs boson and jet production cross sections at the LHC are discussed.Comment: Proceedings of the DIS 2010 workshop, Florence, Ital