Table of contents

The Large Hadron Collider (LHC) is expected to start operating at the European Particle Physics Laboratory, CERN, near Geneva, Switzerland, by the end of 2007. The LHC will collide two proton beams head-on with a total centre-of-mass system energy of 14 TeV and will thus offer a unique opportunity to study particle interactions at the TeV energy scale. The data that will be collected by experiments at the LHC are expected to be decisive in answering fundamental questions such as the origin of the electro-weak symmetry breaking in Nature. The most popular hypothesis to date is the existence of a Higgs field and an associated new type of particle, the Higgs boson, which is yet to be discovered. Furthermore, the LHC will break new ground in the quest for evidence of physics beyond the Standard Model of particle physics. New phenomena such as supersymmetry, extra dimensions, new gauge bosons, or new strongly interacting physics may well be within the reach of the LHC. Such new phenomena at the TeV scale are often required when taking into account all the cosmological and particle physics observations to date, and to stabilize the predictions of the Standard Model.

The CMS experiment is one of the two general purpose detectors designed for the search for new physics at the LHC. Together with ATLAS, CMS will study proton–proton collisions at the highest energies ever realized in the laboratory and sift through billions of events to find, at the start, a handful of unusual ones. However, these events may set the course of our understanding of space and matter for decades to come.

This special issue of Journal of Physics G: Nuclear and Particle Physics is dedicated to the publication of the second volume of the CMS Physics Technical Design Report. The first volume contains the detector performance capabilities and is available via the CMS web page:http://cmsdoc.cern.ch/cms/cpt/tdr/ptdr1_final_bw_full.pdf This second volume covers the capability of the CMS experiment to address physics at the LHC, presenting a large number of physics analyses performed with very detailed simulations of signal and backgrounds, within today's approximations and modelling of these signals and backgrounds.

By publication of the CMS Physics Technical Design Report in Journal of Physics G we hope to offer to the wider physics community an in-depth view of the physics capabilities provided by this unique scientific instrument.

CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider (LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007.

The principal aim of this report is to present the strategy of CMS to explore the rich physics programme offered by the LHC. This volume demonstrates the physics capability of the CMS experiment. The prime goals of CMS are to explore physics at the TeV scale and to study the mechanism of electroweak symmetry breaking—through the discovery of the Higgs particle or otherwise. To carry out this task, CMS must be prepared to search for new particles, such as the Higgs boson or supersymmetric partners of the Standard Model particles, from the start-up of the LHC since new physics at the TeV scale may manifest itself with modest data samples of the order of a few fb⁻¹or less.

The analysis tools that have been developed are applied to study in great detail and with all the methodology of performing an analysis on CMS data specific benchmark processes upon which to gauge the performance of CMS. These processes cover several Higgs boson decay channels, the production and decay of new particles such as Z' and supersymmetric particles, B_sproduction and processes in heavy ion collisions. The simulation of these benchmark processes includes subtle effects such as possible detector miscalibration and misalignment. Besides these benchmark processes, the physics reach of CMS is studied for a large number of signatures arising in the Standard Model and also in theories beyond the Standard Model for integrated luminosities ranging from 1 fb⁻¹to 30 fb⁻¹. The Standard Model processes include QCD, B-physics, diffraction, detailed studies of the top quark properties, and electroweak physics topics such as the Wand Z⁰boson properties. The production and decay of the Higgs particle is studied for many observable decays, and the precision with which the Higgs boson properties can be derived is determined. About ten different supersymmetry benchmark points are analysed using full simulation. The CMS discovery reach is evaluated in the SUSY parameter space covering a large variety of decay signatures. Furthermore, the discovery reach for a plethora of alternative models for new physics is explored, notably extra dimensions, new vector boson high mass states, little Higgs models, technicolour and others. Methods to discriminate between models have been investigated.

This report is organized as follows. Chapter 1, the Introduction, describes the context of this document. Chapters 2–6 describe examples of full analyses, with photons, electrons, muons, jets, missing E_T, B-mesons and τ's, and for quarkonia in heavy ion collisions. Chapters 7–15 describe the physics reach for Standard Model processes, Higgs discovery and searches for new physics beyond the Standard Model.