Production of $$\tau \tau jj$$ττjj final states at the LHC and the TauSpinner algorithm: the spin-2 case

Bahmani, M.; Kalinowski, J.; Richter-Wąs, E.; Wa̧s, Z.

doi:10.1140/epjc/s10052-017-5480-7

Cited by 13 publications

(7 citation statements)

References 37 publications

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“…As demonstrated in Ref. [26], matrix elements calculated for the non-standard type (eg. for non-standard resonance) may differ substantially from the default-standard mode ones.…”

Section: B4 Electroweak Correctionsmentioning

confidence: 99%

Documentation of TauSpinner algorithms: program for simulating spin effects in $$\uptau $$ τ -lepton production at LHC

2019

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The τ-lepton plays an important role in the physics program at the Large Hadron Collider (LHC). It offers a powerful probe in searches for New Physics and can be used to measure parameters of the Standard Model. Spin of τ lepton represents an interesting phenomenological quantity which can be used for the sake of separation of signal from background or in measuring properties of particles decaying to τ leptons. A proper treatment of τ spin effects in the Monte Carlo simulations is important for understanding the detector acceptance as well as for the measurements/use of τ polarization and τ spin correlations in experimental analysis.The TauSpinner package represents a tool which can be used to modify τ spin effects in any sample containing τ leptons. Also production matrix elements can be modified with its help. The general principle of TauSpinner algorithm is to rely on the kinematic of outgoing particles (or jets) only, and to average over all possible initial states accordingly to assumed parton distributions and cross-sections. Incoming on mass-shell parton four-momenta are reconstructed in approximation, but energy-momentum conservation is obeyed. Generated samples of events featuring τ leptons with their decay products, can be used as an input. The information on the polarization and spin correlations, and production/decay matrix elements is reconstructed from the kinematics of the τ lepton(s) (also ν τ in case of W -mediated processes) and τ decay products (also jets). No other information stored in the event record is required, except kinematics of these final state particles. By calculating spin (or production/decay matrix element) weights, attributed on the event-by-event basis, it enables numerical evaluation of modifications due to these effects without the need for regenerating events. With TauSpinner, the experimental techniques developed over years since LEP 1 times are already used and extended for LHC applications.Several applications of TauSpinner were prepared. Elements of program functionalities were presented in appendices of consecutive publications together with explanation how the program can be used in each case. The purpose of present publication is to systematically document physics basis of the program, as well as to give short overwiew of its application domain.

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“…As demonstrated in Ref. [26], matrix elements calculated for the non-standard type (eg. for non-standard resonance) may differ substantially from the default-standard mode ones.…”

Section: B4 Electroweak Correctionsmentioning

confidence: 99%

Documentation of TauSpinner algorithms: program for simulating spin effects in $$\uptau $$ τ -lepton production at LHC

2019

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“…(19) to the quarks and anti-quarks only. Gluon PDF's are used when weight calculation with matrix elements for lepton pair with two jets in final state is used [27]. The γ γ → l + l − contributions can be then taken into account as a part of the 2 → 4 matrix elements.…”

Section: Average Over Incoming Partons Flavourmentioning

confidence: 99%

“…The above affects not only shape but also normalization of the cross-section. In the formulae (27) we do not use running Z -boson width, which remains fixed.…”

Section: The Z -Boson Line-shapementioning

confidence: 99%

Documentation of TauSpinner approach for electroweak corrections in LHC $$Z \rightarrow ll$$ observables

Richter-Wąs

Wa̧s

2019

Eur. Phys. J. C

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The LHC Standard Model Z -boson couplings measurements approach the LEP legacy precision. The calculations of electroweak (EW) corrections available for the Monte Carlo generators become of relevance. Predictions of Z -boson production and decay require classes of QED/EW/QCD corrections and separatly from the production process QCD dynamics. At the LEP time electroweak form-factors and Improved Born Approximation were introduced for non QED genuine weak and line-shape corrections. This formalism was well suited for observables, socalled doubly-deconvoluted the Z -pole region where initialand final-state QED real and virtual emissions were treated separately or were integrated over. The approach was convenient for implementation into Monte Carlo programs for LEP, Belle-BaBar and other future e + e − colliders and for invariant mass of outgoing lepton pair from a few GeV to well above W W and even tt threshold. We attempt now to profit from that, for the LHC pp and 70-150 GeV window for the outgoing lepton pair invariant mass. Our technical focus is on the EW corrections for LHC Z → observables. For this purpose the TauSpinner package, for the reweighting of previously generated events, is enriched with the genuine EW corrections (QED effects subtracted) of the Dizet electroweak library, taken from the LEP era KKMC Monte Carlo. Complete genuine EW O(α) weak loop corrections and dominant higher-order terms are taken into account. For the efficiency and numerical stability look-up tables are used. For LHC observables: the Z -boson line-shape, the outgoing leptons forward-backward asymmetry, the effective leptonic weak mixing angles and finally for the spherical harmonic expansion coefficients of the lepton distributions, corrections are evaluated. Simplified calculations of Effective Born of modified EW couplings are compared with of Improved Born Approximation of complete set of EW formfactors. Approach uses LEP precision tests definitions and a e-mail: Z.Was@cern.ch thus offers consistency checks. The package can be useful to evaluate of observables precision limits and to determine which corrections are then important for LHC and FCC projects phenomenology.

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“…Finally, let us point that such factorization or semi-factorization was necessary to develop the code of TauSpinner, and for discussion of the reliability of its recent extension presented in [44] and in the contributions of proceedings.…”

Section: Table IImentioning

confidence: 99%

Deep Learning Approach to Measurement of Higgs Boson CP in the $H\rightarrow \tau \tau $ Decay Channel

Barberio¹,

Zanzi²,

Was³

et al. 2018

Acta Phys. Pol. B Proc. Suppl.

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The measurement of the Higgs boson CP is amongst the most vital measurements in establishing the nature of the Higgs boson. Of the many decay channels, the ditau final state is one of the most sensitive channels due to the Yukawa coupling allowing access to a potential mixing between CP-even and CP-odd Higgs bosons. While decay modes such as the τ → ρ ± ν are well-established in literature, modes such as the τ → a ± 1 ν are not so. A new approach to encompass many decay modes has been developed using deep learning neural networks. This article summarises work done in assessing the robustness of the approach with respect to detector resolution effects and potential modelling issues. Also discussed is the Drell-Yan background.

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Production of $$\tau \tau jj$$ττjj final states at the LHC and the TauSpinner algorithm: the spin-2 case

Cited by 13 publications

References 37 publications

Documentation of TauSpinner algorithms: program for simulating spin effects in $$\uptau $$ τ -lepton production at LHC

Documentation of TauSpinner algorithms: program for simulating spin effects in $$\uptau $$ τ -lepton production at LHC

Documentation of TauSpinner approach for electroweak corrections in LHC $$Z \rightarrow ll$$ observables

Deep Learning Approach to Measurement of Higgs Boson CP in the $H\rightarrow \tau \tau $ Decay Channel

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