Top Quark Modelling and Generators

Measurements at hadron colliders rely on large scale quantum chromodynamics (QCD) Monte Carlo (MC) production for interpretation of the data. MC simulations allow testing Standard Model (SM) with more accurate and precise calculations to understand perturbative QCD as well as electroweak effects, and extrapolations of the irreducible backgrounds to signal phase-space regions for new physics searches or for the measurements of rare SM processes. In the MC codes, there are many pieces, approximations, and parameters and settings to compare to the data and tune. Precise experimental measurements at the LHC require similar level of precision in theoretical calculations.

Top quark measurements provide important tests of QCD and of the consistency of the standard model (SM). Better understanding of perturbative and non-perturbative effects is required to obtain the highest possible precision in the measurement of top quark properties, in particular, the top quark mass, and its interpretation. Differential measurements done with well-defined top-quark objects are also important to improve the accuracy of predictions in different phase space regions in searches for beyond the SM effects. The uncertainties in the measurements and the predictions need to be at a level where deviations from the predictions from the MC codes or deviations due to new physics effects may become visible.

Papers and notes related to top quark modelling:

• E. Yazgan, “Modelling the Data at the LHC”, Proceedings of Particles and Nuclei International Conference - PANIC2021, 5-10 September, 2021, arXiv:2110.02599 [hep-ex, hep-ph] , PoS(PANIC2021)410

• CMS Collaboration, “A new set of CMS tunes for novel colour reconnection models in PYTHIA8 based on underlying-event data”, CMS-PAS-GEN-17-002

• CMS Collaboration, “Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements”, arXiv:1903.12179 , Eur. Phys. J. C 80 (2020) 4.

• CMS Collaboration, “Study of the underlying event in top quark pair production in pp collisions at 13 TeV”, arXiv:1807.02810 , Eur. Phys. J. C 79 (2019) 123 .

• E. Yazgan, “Quantum Chromodynamics Monte Carlo Tuning Studies in CMS”, arXiv:1906.09952 [hep-ex] , in the proceedings of XXVII International Workshop on Deep-Inelastic Scattering and Related Subjects - DIS2019, 8-12 April 2019, Torino, Italy Report number: CMS CR-2019/076, PoS(DIS2019)080

• E. Yazgan,”Top Quark Modeling and Generators in CMS”, arXiv:1801.05025 [hep-ex, hep-ph] in the proceedings of TOP2017, 10th International Workshop on Top Quark Physics, Braga, Portugal, 17-22 September 2017, Report number: CMS-CR-2017/404

• E. Yazgan, “Top quark modelling in CMS”, arXiv:1709.02585 [hep-ex] , in the proceedings of EPS Conference on High Energy Physics Venice, Italy, 5-12 July 2017, Report number: CMS-CR-2017-204, PoS (EPS-HEP2017) 474 .

• CMS Collaboration, “Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements”, CMS Public Analysis Summary CMS-PAS-GEN-17-001

• CMS Collaboration, “Study of the underlying event in top quark pair production at 13 TeV”, CMS Note CMS-PAS-TOP-17-015

• CMS Collaboration, “Object definitions for top quark analyses at the particle level”, CMS Note, CERN-CMS-NOTE-2017-004

• CMS Collaboration, “Investigations of the impact of the parton shower tuning in Pythia 8 in the modelling of ttbar at sqrt(s)=8 and 13 TeV”, CMS Physics Analysis Summary, CMS-PAS-TOP-16-021

• CMS Collaboration, “Underlying Event Measurement with ttbar+X Events with p-p Collision Data at sqrt(s) = 13 TeV”, CMS Physics Analysis Summary CMS-PAS-TOP-15-017

• CMS Collaboration, “Comparisons of Theory Predictions with Data for ttbar Production in pp Collisions at sqrt(s) = 8 TeV”, CMS Physics Analysis Summary, CMS-PAS-TOP-15-011 .

Presentations related to top quark modelling:

• E. Yazgan, QCD Monte Carlo model tuning studies with CMS data at 13 TeV at 27th Workshop on Deep-Inelastic Scattering and Related Subjects - DIS2019, Torino, Italy
• E. Yazgan, News from CMS , at the PDF4LHC meeting, 13 December 2018, CERN, Geneva, Switzerland.
• E. Yazgan, CMS Needs and Concerns , at the Physics Event Generator Computing Workshop, 26-28 November 2018, CERN, Geneva, Switzerland.
• E. Yazgan, Event Generators in CMS, in CMS Heavy Flavor Tagging Workshop 2018, 11-13 April 2018, Vrije Universiteit Brussel, Belgium.
• E. Yazgan, Top Quark Modelling and Tuning (CMS) , at TOP2017 - 10th International Workshop on Top Quark Physics, 11-22 September 2017, Braga, Portugal.
• E. Yazgan, PDF Order and Pythia8 Tunes in CMS , at the PDF4LHC meeting, 6 September 2017, CERN, Geneva, Switzerland.
• E. Yazgan, Top Quark Event Modelling and Generators in CMS at European Physical Society (EPS) Conference on High Energy Physics, 5-12 July 2017, Venice, Italy
• E. Yazgan, Other Follow-up points from LHC MC Workshop (intro followed by discussion) at The Working Group on Top Physics at the LHC (TOPLHCWG) meeting, 6-7 June 2017, CERN, Geneva, Switzerland.
• A. H. Knue, E. Yazgan Discussion of top modeling systematics for Run 2 in ATLAS+CMS at The Working Group on Top Physics at the LHC (TOPLHCWG) meeting, 6-7 June 2017, CERN, Geneva, Switzerland.
• J. Goh, O. Hindrichs, A. O. M. Iorio, M. Komm, Y. Roh, M. Seidel, P. Silva, E. Yazgan Object Definitions for Top Quark Analyses at the Particle Level CMS-NOTE-2017-004 at The Working Group on Top Physics at the LHC (TOPLHCWG) meeting, 6-7 June 2017, CERN, Geneva, Switzerland. (TOPLHCWG) meeting, 6-7 June 2017, CERN, Geneva, Switzerland.
• E. Yazgan, Underlying event and Multi-Parton Interactions Tuning in CMS , at the ATLAS-CMS Monte Carlo Generators Workshop, 2-5 May 2017, CERN, Geneva, Switzerland.
• E. Yazgan for the ATLAS and CMS Collaborations, <a href=”https://indico.cern.ch/event/537012/timetable/” Differential Distributions: comparison to MCs and interpretation </a> at The Working Group on Top Physics at the LHC (TOPLHCWG) meeting, 21-23 November 2016, CERN, Geneva, Switzerland.
• E. Yazgan, Top Quark Modelling in CMS , in LHC Days in Split, 19-24 September 2016, Split, Crotia.
• E. Yazgan for the ATLAS and CMS Collaborations, ATLAS and CMS pole mass measurements at The Working Group on Top Physics at the LHC (TOPLHCWG) meeting, 17-18 November 2015, CERN, Geneva, Switzerland.
• K. Beernaert, M. Grunewald, E. Yazgan, Towards a Measurement of Spin Correlations in ttbar Events at the LHC using Matrix Element Method at Zurich Phenomenology Workshop (ZPW2014) Monte Carlo Simulation and 2nd Mini-Workshop on Advances in the Matrix Element Methods, University of Zurich, Switzerland.