Exploring High-Purity Multiparton Scattering at Hadron Colliders.

Multiparton interactions are a fascinating phenomenon that occur in almost every high-energy hadron-hadron collision yet are remarkably difficult to study quantitatively. In this Letter, we present a strategy to optimally disentangle multiparton interactions from the primary scattering in a collision. That strategy enables probes of multiparton interactions that are significantly beyond the state of the art, including their characteristic momentum scale, the interconnection between primary and secondary scatters, and the pattern of three and potentially even more simultaneous hard scatterings.

Parton Showering with Higher Logarithmic Accuracy for Soft Emissions.

The accuracy of parton-shower simulations is often a limiting factor in the interpretation of data from high-energy colliders. We present the first formulation of parton showers with accuracy 1 order beyond state-of-the-art next-to-leading logarithms, for classes of observables that are dominantly sensitive to low-energy (soft) emissions, specifically nonglobal observables and subjet multiplicities. This represents a major step toward general next-to-next-to-leading logarithmic accuracy for parton showers.

The Higgs boson turns ten.

The discovery of the Higgs boson, ten years ago, was a milestone that opened the door to the study of a new sector of fundamental physical interactions. We review the role of the Higgs field in the Standard Model of particle physics and explain its impact on the world around us. We summarize the insights into Higgs physics revealed so far by ten years of work, discuss what remains to be determined and outline potential connections of the Higgs sector with unsolved mysteries of particle physics.

Parton Showers beyond Leading Logarithmic Accuracy.

Parton showers are among the most widely used tools in collider physics. Despite their key importance, none so far have been able to demonstrate accuracy beyond a basic level known as leading logarithmic order, with ensuing limitations across a broad spectrum of physics applications. In this Letter, we propose criteria for showers to be considered next-to-leading logarithmic accurate.

Probing the Time Structure of the Quark-Gluon Plasma with Top Quarks.

The tiny droplets of quark gluon plasma (QGP) created in high-energy nuclear collisions experience fast expansion and cooling with a lifetime of a few fm/c. Despite the information provided by probes such as jet quenching and quarkonium suppression, and the excellent description by hydrodynamical models, direct access to the time evolution of the system remains elusive. We point out that the study of hadronically decaying W bosons, notably in events with a top-antitop quark pair, can provide key novel insight into the time structure of the QGP.

Erratum: Fully Differential Vector-Boson-Fusion Higgs Production at Next-to-Next-to-Leading Order [Phys. Rev. Lett. 115, 082002 (2015)].

This corrects the article DOI: 10.1103/PhysRevLett.115.

Determination of the strong coupling constant from measurements of the total cross section for top-antitop-quark production.

We present a determination of the strong coupling constant using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Following a procedure first applied by the CMS Collaboration, we extract individual values of from measurements by different experiments at several centre-of-mass energies, using QCD predictions complete in NNLO perturbation theory, supplemented with NNLL approximations to all orders, and suitable sets of parton distribution functions. The determinations are then combined using a likelihood-based approach, where special emphasis is put on a consistent treatment of theoretical uncertainties and of correlations between various sources of systematic uncertainties.

How Bright is the Proton? A Precise Determination of the Photon Parton Distribution Function.

It has become apparent in recent years that it is important, notably for a range of physics studies at the Large Hadron Collider, to have accurate knowledge on the distribution of photons in the proton. We show how the photon parton distribution function (PDF) can be determined in a model-independent manner, using electron-proton (ep) scattering data, in effect viewing the ep→e+X process as an electron scattering off the photon field of the proton. To this end, we consider an imaginary, beyond the Standard Model process with a flavor changing photon-lepton vertex.

Fully Differential Vector-Boson-Fusion Higgs Production at Next-to-Next-to-Leading Order.

We calculate the fully differential next-to-next-to-leading-order (NNLO) corrections to vector-boson fusion (VBF) Higgs boson production at proton colliders, in the limit in which there is no cross talk between the hadronic systems associated with the two protons. We achieve this using a new "projection-to-Born" method that combines an inclusive NNLO calculation in the structure-function approach and a suitably factorized next-to-leading-order VBF Higgs plus three-jet calculation, using appropriate Higgs plus two-parton counterevents. An earlier calculation of the fully inclusive cross section had found small NNLO corrections, at the 1% level.

SoftKiller, a particle-level pileup removal method.

Existing widely used pileup removal approaches correct the momenta of individual jets. In this article we introduce an event-level, particle-based pileup correction procedure, SoftKiller. It removes the softest particles in an event, up to a transverse momentum threshold that is determined dynamically on an event-by-event basis.

Pileup subtraction for jet shapes.

Jets in high energy hadronic collisions often contain the fingerprints of the particles that produced them. Those fingerprints, and thus the nature of the particles that produced the jets, can be read off with the help of quantities known as jet shapes. Jet shapes are, however, severely affected by pileup, the accumulation in the detector of the residues of the many simultaneous collisions taking place in the Large Hadron Collider (LHC).

Higgs- and Z-boson production with a jet veto.

We derive first next-to-next-to-leading logarithmic resummations for jet-veto efficiencies in Higgs and Z-boson production at hadron colliders. Matching with next-to-next-to-leading order results allows us to provide a range of phenomenological predictions for the LHC, including cross-section results, detailed uncertainty estimates, and comparisons to current widely used tools.

Fat jets for a light higgs boson.

At the LHC associated top quark and Higgs boson production with a Higgs boson decay to bottom quarks has long been a heavily disputed search channel. Recently, it has been found not to be viable. We show how it can be observed by tagging massive Higgs bosons and top jets.

Discovering baryon-number violating neutralino decays at the LHC.

Recently there has been much interest in the use of single-jet mass and jet substructure to identify boosted particles decaying hadronically at the LHC. We develop these ideas to address the challenging case of a neutralino decaying to three quarks in models with baryonic violation of R parity. These decays have previously been found to be swamped by QCD backgrounds.

Jet substructure as a new Higgs-search channel at the Large Hadron Collider.

It is widely considered that, for Higgs boson searches at the CERN Large Hadron Colider, WH and ZH production where the Higgs boson decays to bb are poor search channels due to large backgrounds. We show that at high transverse momenta, employing state-of-the-art jet reconstruction and decomposition techniques, these processes can be recovered as promising search channels for the standard model Higgs boson around 120 GeV in mass.