Abstract
uptau -leptons produced in pp collisions allow to measure Standard Model parameters and offer probes for New Physics. The TauSpinner program can be used to modify spin (or production matrix elements) effects in any uptau sample. It relies on the kinematics of outgoing particles: uptau lepton(s) (also upnu _uptau in case of W-mediated processes, optionally also four-moments of accompanying hard jets) and uptau decay products. No other information is required from the event record. With calculated spin (or production/decay matrix element) weights, attributed on the event-by-event basis, modifications to the spin/decay/production features, is possible without the need for regenerating events. With TauSpinner algorithms, the experimental techniques developed over years since LEP 1 times are already used and extended for LHC applications. The purpose of the present publication is to systematically document physics basis of the program, and to overview its application domain and systematic errors.
Highlights
At LHC experiments, interest in τ leptons lies in the use of decays for the measurements of the properties of hard production processes, of the properties of resonances like W, Z or Higgs boson or in the searches for New Physics
The kinematical frames for τ lepton pair production and τ decays need to be explicitly related by the set of Lorentz transformations with the frames used in matrix element calculations
A further approximation to include longitudinal spin effects only, means that terms Ri, j are set to zero for i, j = x, y. In general those terms can be large, but as they result in dependencies of transverse with respect to τ lepton direction components of τ lepton decay products momenta, they often do not lead to measurable effects and can be dropped
Summary
At LHC experiments, interest in τ leptons lies in the use of decays for the measurements of the properties of hard production processes, of the properties of resonances like W, Z or Higgs boson or in the searches for New Physics. At the beginning the TauSpinner project was focused on the longitudinal spin effects only [11]. It was used to calculate appropriate weights, to include spin effects into (or removed from) the generated events sample. [12], an additional weight was introduced to manipulate the production process by adding or replacing the generated production process with an alternative one, including for example exchange of new intermediate particles. Reference [13] brought the possibility of introducing complete spin effects (longitudinal and transverse) in decays of intermediate Higgs bosons, and in Ref.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
