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Search: authors:"Simone Marzani"

13 papers found.
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Vector boson production in joint resummation

We study the transverse momentum (Q T ) distribution of an electro-weak vector boson produced via the Drell-Yan mechanism, in the context of joint resummation. This formalism allows for the simultaneous resummation of logarithmic contributions that are enhanced at small Q T and at partonic threshold. We extend joint resummation to next-to-next-to leading logarithmic accuracy and we ...

Small-x resummation from HELL

Small-x logarithmic enhancements arising from high-energy gluon emissions affect both the evolution of collinearly-factorized parton densities and partonic coefficient functions. With the higher collider energy reached by the LHC, the prospect of a future high-energy collider, and the recent deep-inelastic scattering (DIS) results at small-x from HERA, providing phenomenological ...

On the Higgs cross section at N3LO+N3LL and its uncertainty

We consider the inclusive production of a Higgs boson in gluon-fusion and we study the impact of threshold resummation at next-to-next-to-next-to-leading logarithmic accuracy (N3LL) on the recently computed fixed-order prediction at next-to-next-to-next-to-leading order (N3LO). We propose a conservative, yet robust way of estimating the perturbative uncertainty from missing higher ...

The Higgs transverse momentum spectrum with finite quark masses beyond leading order

We apply the leading-log high-energy resummation technique recently derived by some of us to the transverse momentum distribution for production of a Higgs boson in gluon fusion. We use our results to obtain information on mass-dependent corrections to this observable, which is only known at leading order when exact mass dependence is included. In the low p T region we discuss the ...

Thinking outside the ROCs: Designing Decorrelated Taggers (DDT) for jet substructure

We explore the scale-dependence and correlations of jet substructure observables to improve upon existing techniques in the identification of highly Lorentz-boosted objects. Modified observables are designed to remove correlations from existing theoretically well-understood observables, providing practical advantages for experimental measurements and searches for new phenomena. We ...

Resummed Higgs cross section at N3LL

Marco Bonvini 1 Simone Marzani 0 0 Institute for Particle Physics Phenomenology, Durham University , South Road, Durham DH1 3LE, England 1 Deutsches Elektronen-Synchroton, DESY, Notkestrae 85, D

NLO+NLL squark and gluino production cross sections with threshold-improved parton distributions

Laenen 3 4 5 Simone Marzani 8 Juan Rojo 7 0 Institute for Theoretical Physics, WWU Münster , 48149 Münster , Germany 1 Institute of Physics, University of Amsterdam , Amsterdam , The Netherlands 2

Top quark pair production beyond NNLO

We construct an approximate expression for the total cross section for the production of a heavy quark-antiquark pair in hadronic collisions at next-to-next-to-next-to-leading order (N3LO) in αs. We use a technique which exploits the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N ...

Soft evolution of multi-jet final states

We present a new framework for computing resummed and matched distributions in processes with many hard QCD jets. The intricate color structure of soft gluon emission at large angles renders resummed calculations highly non-trivial in this case. We automate all ingredients necessary for the color evolution of the soft function at next-to-leading-logarithmic accuracy, namely the ...

Parton distributions with threshold resummation

We construct a set of parton distribution functions (PDFs) in which fixed-order NLO and NNLO calculations are supplemented with soft-gluon (threshold) resummation up to NLL and NNLL accuracy respectively, suitable for use in conjunction with any QCD calculation in which threshold resummation is included at the level of partonic cross sections. These resummed PDF sets, based on the ...

Soft drop

We introduce a new jet substructure technique called “soft drop declustering”, which recursively removes soft wide-angle radiation from a jet. The soft drop algorithm depends on two parameters — a soft threshold z cut and an angular exponent β — with the β = 0 limit corresponding roughly to the (modified) mass drop procedure. To gain an analytic understanding of soft drop and ...

Boosted top production: factorization and resummation for single-particle inclusive distributions

We study single-particle inclusive (1PI) distributions in top-quark pair production at hadron colliders, working in the highly boosted regime where the top-quark p T is much larger than its mass. In particular, we derive a novel factorization formula valid in the small-mass and soft limits of the differential partonic cross section. This provides a framework for the simultaneous ...

Towards an understanding of jet substructure

We present first analytic, resummed calculations of the rates at which wide-spread jet substructure tools tag QCD jets. As well as considering trimming, pruning and the mass-drop tagger, we introduce modified tools with improved analytical and phenomenological behaviours. Most taggers have double logarithmic resummed structures. The modified mass-drop tagger is special in that it ...