Matching NLO parton shower matrix element with exact phase space: case of W→lν(γ) and γ
                     ∗→π
                     +
                     π
                     −(γ)

Nanava, G.; Xu, Q. J.; Wa̧s, Z.

doi:10.1140/epjc/s10052-010-1454-8

Cited by 14 publications

(20 citation statements)

References 44 publications

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“…To gain flexibility of its application, the FORTRAN implementation is being replaced gradually by C++ and instead of HEPEVT, the C++ event structure HepMC [102] is used as the event record. Emission kernel based on complete first order matrix elements for QED final state bremsstrahlung was introduced, following papers [99,103] in [104].…”

Section: Appendix A5: Photosmentioning

confidence: 99%

Precision studies of observables in $$p p \rightarrow W \rightarrow l\nu _l$$ p p → W → l ν l and $$ pp \rightarrow \gamma ,Z \rightarrow l^+ l^-$$ p p → γ , Z → l + l - processes at the LHC

et al. 2017

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This report was prepared in the context of the LPCC Electroweak Precision Measurements at the LHC WG (https://lpcc.web.cern.ch/lpcc/index.php?page=electroweak_ wg) and summarizes the activity of a subgroup dedicated to the systematic comparison of public Monte Carlo codes, which describe the Drell-Yan processes at hadron colliders, in particular at the CERN Large Hadron Collider (LHC). This work represents an important step towards the definition of an accurate simulation framework necessary for very high-precision measurements of electroweak (EW) observables such as the W boson mass and the weak mixing angle. All the codes considered in this report share at least nexta e-mail: alessandro.vicini@mi.infn.it b e-mail: dow@ubpheno.physics.buffalo.edu to-leading-order (NLO) accuracy in the prediction of the total cross sections in an expansion either in the strong or in the EW coupling constant. The NLO fixed-order predictions have been scrutinized at the technical level, using exactly the same inputs, setup and perturbative accuracy, in order to quantify the level of agreement of different implementations of the same calculation. A dedicated comparison, again at the technical level, of three codes that reach next-to-nextto-leading-order (NNLO) accuracy in quantum chromodynamics (QCD) for the total cross section has also been performed. These fixed-order results are a well-defined reference that allows a classification of the impact of higher-order sets of radiative corrections. Several examples of higherorder effects due to the strong or the EW interaction are discussed in this common framework. Also the combination 123 280 Page 2 of 53 Eur. Phys. J. C (2017) 77 :280 of QCD and EW corrections is discussed, together with the ambiguities that affect the final result, due to the choice of a specific combination recipe. All the codes considered in this report have been run by the respective authors, and the results presented here constitute a benchmark that should be always checked/reproduced before any high-precision analysis is conducted based on these codes. In order to simplify these benchmarking procedures, the codes used in this report, together with the relevant input files and running instructions, can be found in a repository at https://twiki.cern.ch/twiki/ bin/view/Main/DrellYanComparison.

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Section: Appendix A5: Photosmentioning

confidence: 99%

Precision studies of observables in $$p p \rightarrow W \rightarrow l\nu _l$$ p p → W → l ν l and $$ pp \rightarrow \gamma ,Z \rightarrow l^+ l^-$$ p p → γ , Z → l + l - processes at the LHC

et al. 2017

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“…Phase space parameterization was carefully documented in [26]. Gradually for selected decays [26][27][28]54], also exact matrix elements were implemented and could be activated in place of universal kernels. 4 Originally [23], only single photon radiation was possible and approximations in the universal kernel were present even in the soft photon region.…”

Section: Photosmentioning

confidence: 99%

“…Precision tag for the QED FSR calculation implemented in PHOTOS or SANC is finally given for a broad class of observables: first for the photonic bremsstrahlung and then for complete FSR corrections. 2 In our work we concentrate on the applications for LHC experiments of techniques, calculations and programs developed earlier: PHOTOS [23][24][25][26][27][28][29], SANC [30][31][32][33][34][35][36][37][38][39] and KKMC 2 In this paper we use the name photonic bremsstrahlung whenever we want to stress that only diagrams resulting from supplementing Born level amplitudes with photon lines are considered. The name final-state radiation is used when we stress presence of additional pairs and finalstate interaction when we want to discuss separation with remaining parts of electroweak interactions.…”

Section: Introductionmentioning

confidence: 99%

QED bremsstrahlung in decays of electroweak bosons

2013

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Isolated lepton momenta, in particular their directions are the most precisely measured quantities in pp collisions at LHC. This offers opportunities for multitude of precision measurements.It is of practical importance to verify if precision measurements with leptons in the final state require all theoretical effects evaluated simultaneously or if QED bremsstrahlung in the final state can be separated without unwanted precision loss.Results for final-state bremsstrahlung in the decays of narrow resonances are obtained from the Feynman rules of QED in an unambiguous way and can be controlled with a very high precision. Also for resonances of non-negligible width, if calculations are appropriately performed, such separation from the remaining electroweak effects can be expected.Our paper is devoted to validation that final-state QED bremsstrahlung can indeed be separated from the rest of QCD and electroweak effects, in the production and decay of Z and W bosons, and to estimation of the resulting systematic error. The quantitative discussion is based on Monte Carlo programs PHOTOS and SANC, as well as on KKMC which is used for benchmark results. We show that for a large class of W and Z boson observables as used at LHC, the theoretical error on photonic bremsstrahlung is 0.1 or 0.2 %, depending on the program options used. An overall theoretical error on the QED final-state radiation, i.e. taking into account missing corrections due to pair emission and interference with initial state radiation is estimated respectively at 0.2 % or 0.3 % again depending on the program option used. a

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“…In C++ applications, the complete first-order matrix elements for the two-body decays of the Z [16] and W [26] decays into a lepton pair are now available. Kernels with complete matrix elements, for the decays of scalar B mesons into a pair of scalars [25] are available for the C++ users as well.…”

Section: Photos Monte Carlo For Bremsstrahlung and Its Systematic Uncmentioning

confidence: 99%

“…Kernels with complete matrix elements, for the decays of scalar B mesons into a pair of scalars [25] are available for the C++ users as well. For K → lνπ and for γ * → π + π − decays [26,27] matrix element based kernels are still available for tests only. Properly oriented reference frames are needed in those cases.…”

Section: Photos Monte Carlo For Bremsstrahlung and Its Systematic Uncmentioning

confidence: 99%

New hadronic currents in TAUOLA: for confrontation with the experimental data

Wa̧s

2012

Nuclear Physics B - Proceedings Supplements

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The status of implementation of new hadronic currents into the Monte Carlo system for simulation of τ-lepton production and decay in high-energy accelerator experiments is reviewed. Since the τ-lepton conference in 2010 substantial progress was achieved: (i) For the TAUOLA Monte Carlo generator of τ-lepton decays, automated and simultaneous use of many versions of form factors for the calculation of optional weights for fits was developed and checked to work in the Belle and BaBar software environment. Alternative parameterizations of hadronic currents based on the Resonance Chiral approach are available now. This was achieved for more than 88% of the total τ hadronic width.(ii) the TAUOLA universal interface based on HepMC (the C++ event record) is available. This is the case for C++ users of PHOTOS Monte Carlo for radiative corrections in decays, as well. An algorithm for weighted events to explore spin effects in analysis of hard processes was prepared. (iii) Kernels featuring a complete first-order matrix element are available now for PHOTOS users interested in decays of Z and W bosons. New tests with different options of matrix elements for those and for K l3 decays are available as well.Presented results illustrate the status of the projects performed in collaboration with

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Matching NLO parton shower matrix element with exact phase space: case of W→lν(γ) and γ ∗→π + π −(γ)

Cited by 14 publications

References 44 publications

Precision studies of observables in $$p p \rightarrow W \rightarrow l\nu _l$$ p p → W → l ν l and $$ pp \rightarrow \gamma ,Z \rightarrow l^+ l^-$$ p p → γ , Z → l + l - processes at the LHC

Precision studies of observables in $$p p \rightarrow W \rightarrow l\nu _l$$ p p → W → l ν l and $$ pp \rightarrow \gamma ,Z \rightarrow l^+ l^-$$ p p → γ , Z → l + l - processes at the LHC

QED bremsstrahlung in decays of electroweak bosons

New hadronic currents in TAUOLA: for confrontation with the experimental data

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