The FP420 R&D Project: Higgs and New Physics with forward protons at the LHC

TL;DR

The FP420 R&D project develops forward proton detectors at 420m from LHC interaction points to enable precise measurements of exclusive processes and search for new physics, including Higgs bosons, with detailed detector and physics analyses.

Contribution

It introduces a novel detector system at 420m for the LHC, enabling new measurements of central exclusive production and related physics processes.

Findings

Design of silicon tracker and fast-timing detectors for LHC

Feasibility of measuring Higgs via exclusive production

Detailed trigger and background rejection strategies

Abstract

We present the FP420 R&D project, which has been studying the key aspects of the development and installation of a silicon tracker and fast-timing detectors in the LHC tunnel at 420 m from the interaction points of the ATLAS and CMS experiments. These detectors would measure precisely very forward protons in conjunction with the corresponding central detectors as a means to study Standard Model (SM) physics, and to search for and characterise New Physics signals. This report includes a detailed description of the physics case for the detector and, in particular, for the measurement of Central Exclusive Production, pp --> p + phi + p, in which the outgoing protons remain intact and the central system phi may be a single particle such as a SM or MSSM Higgs boson. Other physics topics discussed are gamma-gamma and gamma-p interactions, and diffractive processes. The report includes a detailed study of the trigger strategy, acceptance, reconstruction efficiencies, and expected yields for a particular p p --> p H p measurement with Higgs boson decay in the b-bbar mode. The document also describes the detector acceptance as given by the LHC beam optics between the interaction points and the FP420 location, the machine backgrounds, the new proposed connection cryostat and the moving ("Hamburg") beam-pipe at 420 m, and the radio-frequency impact of the design on the LHC. The last part of the document is devoted to a description of the 3D silicon sensors and associated tracking performances, the design of two fast-timing detectors capable of accurate vertex reconstruction for background rejection at high-luminosities, and the detector alignment and calibration strategy.