One of the triumphs of modern particle physics has been the extent to which Quantum Chromodynamics (QCD) has successfully accounted for the strong interaction processes observed at high-energy particle colliders, for example the production of heavy quarks and jets of particles, and the short-distance parton structure of the proton. This book gives a detailed overview of collider physics with special emphasis on the study of QCD. After a general description of the QCD Lagrangian, and the properties of asymptotic freedom and colour confinement which derive from it, the most important applications at high-energy colliders are described in detail. These include the production of jets, heavy quarks, electroweak gauge bosons and Higgs bosons. The various methods of measuring the strong coupling constant are summarised. Many of the theoretical results are calculated from first principles, and the book will be both a textbook and a valuable source of reference material for all particle physicists.

We present a new analysis of parton distributions of the proton. This incorporates a wide range of new data, an improved treatment of heavy flavours and a reexamination of prompt photon production. The new set (MRST) shows systematic differences from previous sets of partons which can be identified with particular features of the new data and with improvements in the analysis. An 'explanation' of the behaviour seen on the Caldwell plot is offered.

We present a study of the central exclusive production (CEP) of meson pairs 1 , M M , at sufficiently high invariant mass that a perturbative QCD formalism is applicable. Within this framework, M M production proceeds via the gg → M M hard scattering sub-process, which can be calculated within the hard exclusive formalism. We present explicit calculations for the gg → M M helicity amplitudes for different meson states and, using these, show results for meson pair CEP in the perturbative regime. a KRYSTHAL collaboration b speaker

No abstract

Physics at the Large Hadron Collider (LHC) and the International e + e − Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC / LC Study Group so far is summarised in this report. Possible topics for future studies are outlined.4

We study the production of same-sign W boson pairs at the LHC in double parton interactions. Compared with simple factorised double parton distributions (dPDFs), we show that the recently developed dPDFs, GS09, lead to non-trivial kinematic correlations between the W bosons. A numerical study of the prospects for observing this process using same-sign dilepton signatures, including W ± W ± jj, di-boson and heavy flavour backgrounds, at 14 TeV centre-of-mass energy is then performed. It is shown that a small excess of same-sign dilepton events from double parton scattering over a background dominated by single scattering W ± Z(γ * ) production could be observed at the LHC.

We argue that the recent LHCb observation of J/ψ-pair production indicates a significant contribution from double parton scattering, in addition to the standard single parton scattering component. We propose a method to measure the double parton scattering at LHCb using leptonic final states from the decay of two prompt J/ψ mesons.PACS numbers: 12.20. Ds, 13.85.Ni, 14.40.Lb Introduction. The Large Hadron Collider (LHC) provides a unique environment for precise measurements of hitherto poorly understood phenomena. Since the flux of incoming partons increases with the collision energy, there is a high probability at the LHC of multiparton scattering, i.e. scattering of more than one pair of partons in the same hadron-hadron collision. The partonparton correlations and distributions of multiple partons within a proton are difficult to address within the framework of perturbative QCD. Therefore detailed experimental studies of multi-parton interactions are of great importance. In particular, it is widely expected that measurements of double parton scattering (DPS) processes with final states carrying relatively large transverse momentum (p T ) will provide relevant information on the nature of multiple scattering. Probing DPS processes using leptonic final states has been discussed in [1]. In this Letter, we discuss how observing four-muon final states from pair production of J/ψ could provide additional experimental input.

We study the sensitivity of our recent MSTW 2008 NLO and NNLO PDF analyses to the values of the charm-and bottom-quark masses, and we provide additional public PDF sets for a wide range of these heavy-quark masses. We quantify the impact of varying m c and m b on the cross sections for W , Z and Higgs production at the Tevatron and the LHC. We generate 3-and 4-flavour versions of the (5-flavour) MSTW 2008 PDFs by evolving the input PDFs and α S determined from fits in the 5-flavour scheme, including the eigenvector PDF sets necessary for calculation of PDF uncertainties. As an example of their use, we study the difference in the Z total cross sections at the Tevatron and LHC in the 4-and 5-flavour schemes. Significant differences are found, illustrating the need to resum large logarithms in Q 2 /m 2 b by using the 5-flavour scheme. The 4-flavour scheme is still necessary, however, if cuts are imposed on associated (massive) b-quarks, as is the case for the experimental measurement of Zbb production and similar processes.