Production of prompt photons associated with jets at LHC in kT-factorization

We use the kT–factorization approach to calculate total and differential cross sections of associated production of prompt photons and hadronic jets at the LHC energies. Our consideration relies on the pegasus Monte-Carlo generator with implemented ℴ(αα2s) off-shell gluon–gluon fusion subprocess g*g* → γqq− and several subleading quark-initiated contributions from ℴ(ααs) and ℴ(αα2s) subprocesses, taken into account in the collinear limit. Using Monte-Carlo generators CASCADE and PYTHIA, we investigate parton showering effects and compare our predictions with the data, taken by CMS and ATLAS collaborations at the LHC. We demostrate reasonabledescription of the data and the importance of parton shower effects in the kT–factorization.

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Higgs Boson Pair Production: Monte Carlo Generator Interface and Parton Shower

Acta Physica Polonica B Proceedings Supplement ◽

10.5506/aphyspolbsupp.11.295 ◽

2018 ◽

Vol 11 (2) ◽

pp. 295

Author(s):

S.P. Jones

Keyword(s):

Monte Carlo ◽

Higgs Boson ◽

Pair Production ◽

Parton Shower ◽

Monte Carlo Generator ◽

Boson Pair ◽

Boson Pair Production

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Transverse momentum dependent PDFs at N3LO

Journal of High Energy Physics ◽

10.1007/jhep09(2020)146 ◽

2020 ◽

Vol 2020 (9) ◽

Cited By ~ 2

Author(s):

Markus A. Ebert ◽

Bernhard Mistlberger ◽

Gherardo Vita

Keyword(s):

Transverse Momentum ◽

Cross Sections ◽

Production Cross ◽

Gluon Fusion ◽

Building Blocks ◽

Distribution Functions ◽

Leading Order ◽

Parton Distribution Functions ◽

Transverse Momentum Dependent ◽

Collinear Limit

Abstract We compute the quark and gluon transverse momentum dependent parton distribution functions at next-to-next-to-next-to-leading order (N3LO) in perturbative QCD. Our calculation is based on an expansion of the differential Drell-Yan and gluon fusion Higgs production cross sections about their collinear limit. This method allows us to employ cutting edge multiloop techniques for the computation of cross sections to extract these universal building blocks of the collinear limit of QCD. The corresponding perturbative matching kernels for all channels are expressed in terms of simple harmonic polylogarithms up to weight five. As a byproduct, we confirm a previous computation of the soft function for transverse momentum factorization at N3LO. Our results are the last missing ingredient to extend the qT subtraction methods to N3LO and to obtain resummed qT spectra at N3LL′ accuracy both for gluon as well as for quark initiated processes.

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CASCADE3 A Monte Carlo event generator based on TMDs

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09203-8 ◽

2021 ◽

Vol 81 (5) ◽

Author(s):

S. Baranov ◽

A. Bermudez Martinez ◽

L. I. Estevez Banos ◽

F. Guzman ◽

F. Hautmann ◽

...

Keyword(s):

Monte Carlo ◽

Transverse Momentum ◽

Parton Shower ◽

Monte Carlo Event ◽

Event Generator ◽

Initial State ◽

Collinear Factorization ◽

Transverse Momentum Dependent ◽

Monte Carlo Event Generator ◽

Parton Showering

AbstractThe Cascade3 Monte Carlo event generator based on Transverse Momentum Dependent (TMD) parton densities is described. Hard processes which are generated in collinear factorization with LO multileg or NLO parton level generators are extended by adding transverse momenta to the initial partons according to TMD densities and applying dedicated TMD parton showers and hadronization. Processes with off-shell kinematics within $$k_{{t}}$$ k t -factorization, either internally implemented or from external packages via LHE files, can be processed for parton showering and hadronization. The initial state parton shower is tied to the TMD parton distribution, with all parameters fixed by the TMD distribution.

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Photon and leptons induced processes at the LHC

Journal of High Energy Physics ◽

10.1007/jhep12(2021)073 ◽

2021 ◽

Vol 2021 (12) ◽

Author(s):

Luca Buonocore ◽

Paolo Nason ◽

Francesco Tramontano ◽

Giulia Zanderighi

Keyword(s):

Cross Sections ◽

Parton Shower ◽

Search Strategy ◽

Scalar Particle ◽

Leading Order ◽

Hadronic Tensor ◽

Factorization Approach ◽

Exotic Particles ◽

Initial States ◽

Standard Model Process

Abstract We study a few basic photon- and lepton-initiated processes at the LHC which can be computed using the recently developed photon and lepton parton densities. First, we consider the production of a massive scalar particle initiated by lepton-antilepton annihilation and photon-photon fusion as representative examples of searches of exotic particles. Then we study lepton-lepton scattering, since this Standard-Model process may be observable at the LHC. We examine these processes at leading and next-to-leading order and, using the POWHEG method, we match our calculations to parton shower programs that implement the required lepton or photon initial-states. We assess the typical size of cross-sections and their uncertainties and discuss the preferred choices for the factorization scale. These processes can also be computed starting directly from the lepto-production hadronic tensor, leading to a result where some collinear-enhanced QED corrections are missing, but all strong corrections are included. Thus, we are in the unique position to perform a comparison of results obtained via the factorization approach to a calculation that does not have strong corrections. This is particularly relevant in the case of lepton-scattering, that is more abundant at lower energies where it is affected by larger strong corrections. We thus compute this process also with the hadronic-tensor method, and compare the results with those obtained with POWHEG. Finally, for some lepton-lepton scattering processes, we compare the size of the signal to the main quark-induced background, which is double Drell-Yan production, and outline a preliminary search strategy to enhance the signal to background ratio.

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IR-improved DGLAP parton shower effects for associated production of a W boson and jets in pp collisions at s = 8 and 13 TeV

International Journal of Modern Physics A ◽

10.1142/s0217751x20501973 ◽

2020 ◽

Vol 35 (32) ◽

pp. 2050197

Author(s):

B. Shakerin ◽

B. F. L. Ward

Keyword(s):

Matrix Element ◽

Energy Dependence ◽

Cross Sections ◽

Parton Shower ◽

W Boson ◽

Exact Formula ◽

Leading Order ◽

Angular Correlations ◽

Associated Production ◽

Theoretical Predictions

In a previous paper, hereafter referred to as I, we have analyzed the 7 TeV LHC data on [Formula: see text] events from the standpoint of IR-improved DGLAP parton shower effects, using the IR-improved Herwiri1.031 parton shower MC in comparison with the Herwig6.5 parton shower MC in the context of the exact [Formula: see text] matrix element matched parton shower framework provided by MG5_aMC@NLO. In this paper, we extend this analysis to the LHC 8 and 13 TeV data to investigate the energy dependence of the results obtained in I. Specifically, [Formula: see text] events are generated in the MADGRAPH5_aMC@NLO framework and showered by HERWIG6.521 and HERWIRI1.031 with [Formula: see text] and 0 GeV, respectively. The differential cross sections are reported as functions of jet multiplicity, transverse linear momenta [Formula: see text], the jet pseudorapidity [Formula: see text] and the scalar sum of jet transverse momenta [Formula: see text] for different jet multiplicities 1–3. The dijet cross sections as functions of transverse linear momenta, invariant mass of the dijet and the jet separation are shown as well. Distributions of angular correlations between the jets and the muon are examined as well and the corresponding cross sections are presented. The respective measured cross sections are compared with the exact next-to-leading-order (NLO) matrix element matched parton shower theoretical predictions provided by MADGRAPH5_aMC@NLO/HERWIRI1.031 [Formula: see text] and MADGRAPH5_aMC@NLO/HERWIG6.521 [Formula: see text] and the phenomenological consequences are discussed with an eye toward their energy dependence.

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Electron Scattering in Solids

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133618 ◽

1990 ◽

Vol 48 (2) ◽

pp. 4-5

Author(s):

Ryuichi Shimizu ◽

Ze-Jun Ding

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Angular Distribution ◽

Elastic Scattering ◽

Electron Scattering ◽

Cross Sections ◽

Expansion Method ◽

Electron Excitation ◽

Partial Wave Expansion ◽

Backscattered Electrons

Monte Carlo simulation has been becoming most powerful tool to describe the electron scattering in solids, leading to more comprehensive understanding of the complicated mechanism of generation of various types of signals for microbeam analysis.The present paper proposes a practical model for the Monte Carlo simulation of scattering processes of a penetrating electron and the generation of the slow secondaries in solids. The model is based on the combined use of Gryzinski’s inner-shell electron excitation function and the dielectric function for taking into account the valence electron contribution in inelastic scattering processes, while the cross-sections derived by partial wave expansion method are used for describing elastic scattering processes. An improvement of the use of this elastic scattering cross-section can be seen in the success to describe the anisotropy of angular distribution of elastically backscattered electrons from Au in low energy region, shown in Fig.l. Fig.l(a) shows the elastic cross-sections of 600 eV electron for single Au-atom, clearly indicating that the angular distribution is no more smooth as expected from Rutherford scattering formula, but has the socalled lobes appearing at the large scattering angle.

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Collinear expansion for color singlet cross sections

Journal of High Energy Physics ◽

10.1007/jhep09(2020)181 ◽

2020 ◽

Vol 2020 (9) ◽

Author(s):

Markus A. Ebert ◽

Bernhard Mistlberger ◽

Gherardo Vita

Keyword(s):

Cross Section ◽

Cross Sections ◽

Production Cross ◽

Gluon Fusion ◽

Building Blocks ◽

Color Singlet ◽

Final State ◽

Beam Function ◽

Kinematic Limit ◽

State Radiation

Abstract We demonstrate how to efficiently expand cross sections for color-singlet production at hadron colliders around the kinematic limit of all final state radiation being collinear to one of the incoming hadrons. This expansion is systematically improvable and applicable to a large class of physical observables. We demonstrate the viability of this technique by obtaining the first two terms in the collinear expansion of the rapidity distribution of the gluon fusion Higgs boson production cross section at next-to-next-to leading order (NNLO) in QCD perturbation theory. Furthermore, we illustrate how this technique is used to extract universal building blocks of scattering cross section like the N-jettiness and transverse momentum beam function at NNLO.

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Development of SiO2 based doped with LiF, Cr2O3, CoO4 and B2O3 glasses for gamma and fast neutron shielding

Radiochimica Acta ◽

10.1515/ract-2020-0067 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Bünyamin Aygün ◽

Erdem Şakar ◽

Abdulhalik Karabulut ◽

Bünyamin Alım ◽

Mohammed I. Sayyed ◽

...

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Fast Neutron ◽

Cross Sections ◽

Gamma Ray ◽

Absorbed Dose ◽

Neutron Shielding ◽

Shielding Properties ◽

Effective Neutron ◽

Simulation Codes

AbstractIn this study, the fast neutron and gamma-ray absorption capacities of the new glasses have been investigated, which are obtained by doping CoO,CdWO4,Bi2O3, Cr2O3, ZnO, LiF,B2O3 and PbO compounds to SiO2 based glasses. GEANT4 and FLUKA Monte Carlo simulation codes have been used in the planning of the samples. The glasses were produced using a well-known melt-quenching technique. The effective neutron removal cross-sections, mean free paths, half-value layer, and transmission numbers of the fabricated glasses have been calculated through both GEANT4 and FLUKA Monte Carlo simulation codes. Experimental neutron absorbed dose measurements have been carried out. It was found that GS4 glass has the best neutron protection capacity among the produced glasses. In addition to neutron shielding properties, the gamma-ray attenuation capacities, were calculated using newly developed Phy-X/PSD software. The gamma-ray shielding properties of GS1 and GS2 are found to be equivalent to Pb-based glass.

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