Abstract
The TauSpinner algorithm is a tool that allows one to modify the physics model of the Monte Carlo generated samples due to the changed assumptions of event production dynamics, but without the need of re-generating events. With the help of weights tau -lepton production or decay processes can be modified accordingly to a new physics model. In a recent paper a new version TauSpinner ver.2.0.0 has been presented which includes a provision for introducing non-standard states and couplings and study their effects in the vector-boson-fusion processes by exploiting the spin correlations of tau -lepton pair decay products in processes where final states include also two hard jets. In the present paper we document how this can be achieved taking as an example the non-standard spin-2 state that couples to Standard Model particles and tree-level matrix elements with complete helicity information included for the parton–parton scattering amplitudes into a tau -lepton pair and two outgoing partons. This implementation is prepared as the external (user-provided) routine for the TauSpinner algorithm. It exploits amplitudes generated by MadGraph5 and adapted to the TauSpinner algorithm format. Consistency tests of the implemented matrix elements, re-weighting algorithm and numerical results for observables sensitive to tau polarisation are presented.
Highlights
Before discussing TauSpinner as a tool for studying observables of New Physics let us briefly recall some virtues of the TauSpinner algorithm
In a recent paper a new version TauSpinner ver.2.0.0 has been presented which includes a provision for introducing non-standard states and couplings and study their effects in the vector-boson-fusion processes by exploiting the spin correlations of τ -lepton pair decay products in processes where final states include two hard jets
In the present paper we document how this can be achieved taking as an example the non-standard spin-2 state that couples to Standard Model particles and tree-level matrix elements with complete helicity information included for the parton–parton scattering amplitudes into a τ -lepton pair and two outgoing partons
Summary
Before discussing TauSpinner as a tool for studying observables of New Physics let us briefly recall some virtues of the TauSpinner algorithm. Since τ -leptons cannot be observed directly due to their short life-time with more than 20 different decay channels, each with somewhat distinct signature, recalculating and reanalyzing observables involving τ decays is time consuming. The τ -lepton spin polarisation can be inferred from their decays, contrary to the case of electron or muon signatures.
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