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City University of New York (CUNY)

NLO Computations

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Full-Text Articles in Physics

Top-Quark Pair Hadroproduction In Association With A Heavy Boson At Nlo+Nnll Including Ew Corrections, Alessandro Broggio, Andrea Ferroglia, Rikkert Frederix, Davide Pagani, Benjamin D. Pecjak, Ioannis Tsinikos Jan 2019

Top-Quark Pair Hadroproduction In Association With A Heavy Boson At Nlo+Nnll Including Ew Corrections, Alessandro Broggio, Andrea Ferroglia, Rikkert Frederix, Davide Pagani, Benjamin D. Pecjak, Ioannis Tsinikos

Publications and Research

This work studies the associated production of a top-quark pair with a W, Z, or Higgs boson at the LHC. Predictions for the total cross sections as well as for several differential distributions of the massive particles in the final state are provided. These predictions, valid for the LHC operating at 13 TeV, include without any approximation all the NLO electroweak and QCD contributions of O(αisαj+1) with i + j = 2, 3. In addition, the predictions presented here improve upon the NLO QCD results by adding the effects of soft gluon emission …


Nnll Resummation For The Associated Production Of A Top Pair And A Higgs Boson At The Lhc, Alessandro Broggio, Andrea Ferroglia, Ben D. Pecjak, Li Lin Yang Feb 2017

Nnll Resummation For The Associated Production Of A Top Pair And A Higgs Boson At The Lhc, Alessandro Broggio, Andrea Ferroglia, Ben D. Pecjak, Li Lin Yang

Publications and Research

We study the resummation of soft gluon emission corrections to the production of a top-antitop pair in association with a Higgs boson at the Large Hadron Collider. Starting from a soft-gluon resummation formula derived in previous work, we develop a bespoke parton-level Monte Carlo program which can be used to calculate the total cross section along with differential distributions. We use this tool to study the phenomenological impact of the resummation to next-to-next-to-leading logarithmic (NNLL) accuracy, finding that these corrections increase the total cross section and the differential distributions with respect to NLO calculations of the same observables.


Associated Production Of A Top Pair And A W Boson At Next-To-Next-To-Leading Logarithmic Accuracy, Alessandro Broggio, Andrea Ferroglia, Giovanni Ossola, Ben D. Pecjak Sep 2016

Associated Production Of A Top Pair And A W Boson At Next-To-Next-To-Leading Logarithmic Accuracy, Alessandro Broggio, Andrea Ferroglia, Giovanni Ossola, Ben D. Pecjak

Publications and Research

We consider soft gluon emission corrections to the production of a top-antitop pair in association with a W boson at the Large Hadron Collider. We obtain a soft-gluon resummation formula for this production process which is valid up to next-to-next-to-leading logarithmic accuracy. We evaluate the soft gluon resummation formula in Mellin space by means of an in-house parton level Monte Carlo code which allows us to obtain predictions for the total cross section as well as for several differential distributions. We study the impact of the soft-gluon resummation corrections in comparison to fixed order calculations.


Associated Production Of A Top Pair And A Higgs Boson Beyond Nlo, Alessandro Broggio, Andrea Ferroglia, Ben D. Pecjak, Adrian Signer, Li Lin Yang Mar 2016

Associated Production Of A Top Pair And A Higgs Boson Beyond Nlo, Alessandro Broggio, Andrea Ferroglia, Ben D. Pecjak, Adrian Signer, Li Lin Yang

Publications and Research

We consider soft gluon emission corrections to the production of a top-antitop pair in association with a Higgs boson at hadron colliders. In particular, we present a softgluon resummation formula for this production process and gather all elements needed to evaluate it at next-to-next-to-leading logarithmic order. We employ these results to obtain approximate next-to-next-to-leading order (NNLO) formulas, and implement them in a bespoke parton-level Monte Carlo program which can be used to calculate the total cross section along with arbitrary differential distributions. We use this tool to study the phenomenological impact of the approximate NNLO corrections, finding that they increase …


Nnlo Hard Functions In Massless Qcd, Alessandro Broggio, Andrea Ferroglia, Ben D. Pecjak, Zhibai Zhang Dec 2014

Nnlo Hard Functions In Massless Qcd, Alessandro Broggio, Andrea Ferroglia, Ben D. Pecjak, Zhibai Zhang

Publications and Research

We derive the hard functions for all 2 → 2 processes in massless QCD up to next-to-next-to-leading order (NNLO) in the strong coupling constant. By employing the known one- and two-loop helicity amplitudes for these processes, we obtain analytic expressions for the ultraviolet and infrared finite, minimally subtracted hard functions, which are matrices in color space. These hard functions will be useful in carrying out higher-order resummations in processes such as dijet and highly energetic top-quark pair production by means of soft-collinear effective theory methods.


Multi-Leg One-Loop Massive Amplitudes From Integrand Reduction Via Laurent Expansion, Hans Van Deurzen, Gionata Luisoni, Pierpaolo Mastrolia, Edoardo Mirabella, Giovanni Ossola, Tiziano Peraro Mar 2014

Multi-Leg One-Loop Massive Amplitudes From Integrand Reduction Via Laurent Expansion, Hans Van Deurzen, Gionata Luisoni, Pierpaolo Mastrolia, Edoardo Mirabella, Giovanni Ossola, Tiziano Peraro

Publications and Research

We present the application of a novel reduction technique for one-loop scattering amplitudes based on the combination of the integrand reduction and Laurent expansion. We describe the general features of its implementation in the computer code Ninja, and its interface to GoSam. We apply the new reduction to a series of selected processes involving massive particles, from six to eight legs.


Scattering Amplitudes From Unitarity-Based Reduction Algorithm At The Integrand-Level, P. Mastrolia, Giovanni Ossola, T. Reiter, F. Tramontano Aug 2010

Scattering Amplitudes From Unitarity-Based Reduction Algorithm At The Integrand-Level, P. Mastrolia, Giovanni Ossola, T. Reiter, F. Tramontano

Publications and Research

Samurai is a tool for the automated numerical evaluation of one-loop corrections to any scattering amplitudes within the dimensional-regularization scheme. It is based on the decomposition of the integrand according to the OPP-approach, extended to accommodate an implementation of the generalized d-dimensional unitarity-cuts technique, and uses a polynomial interpolation exploiting the Discrete Fourier Transform. samurai can process integrands written either as numerator of Feynman diagrams or as product of tree-level amplitudes. We discuss some applications, among which the 6- and 8-photon scattering in QED, and the 6-quark scattering in QCD. samurai has been implemented as a Fortran90 library, publicly available, …