Z. Was homepage | Z. Czyczula e-mail: Zofia.Czyczula (at) cern.ch | T. Przedzinski hompege



As of 2012-07-25 TauSpinner is merged with Tauola++, for further develpments check Tauola++ website.

This website will no longer be updated

TauSpinner: tau spin reweight algorithm
Authors: Z. Czyczula, T. Przedzinski, Z. Was


PHYSICS PURPOSE:
For previously generated sample involving tau, its spin effects can be:
  1. validated. Eg. if spin effects were taken into account when events were generated
  2. calculate spin weght for previously generated events and stored on the tape.
    • In original sample spin effects could have been missing.
      Then spin weight will be in range (0 , 2n);
      n denotes number of taus in final state.
    • In original sample spin effects are eg for W+ and we would like to see how it would look if H+ was present instead.
  3. reweight on flight such events with spin weight. Such unweighted events can be then monitored with MC-Tester for quick evaluation of spin effects
At present only nine main decay channels of tau have their spin effects used in algorithm.
These channels cover already now above 95% of total tau width.

For more information on agorithm use see README
(This README is included in distribution tarball as well)


The most up-to-date version is available from
Tauola++ website



DOWNLOAD: version 1.0 (as of 07.Dec.11)



Development version

QUICK LOOK AT SUBDIRECTORIES, NUMERICAL RESULTS AND OLD VERSIONS:

LIST OF HARD PROCESSES:
    *
  • W^- &rarr tau^- nu_tau
  • W^+ &rarr tau^+ nu_tau
    *
  • H^- &rarr tau^- nu_tau
  • H^+ &rarr tau^+ nu_tau
*
  • gamma^* &rarr tau^+ tau^-
  • Z &rarr tau^+ tau^-
    *
  • h &rarr tau^+ tau^-
  • a &rarr tau^+ tau^-

    • Partial kinematical information is used (4 momenta of taus and their parent only).
    Only longitudinal spin effects.

    LIST OF TAU DECAY CHANNELS WHEN SPIN EFFECTS ARE TAKEN:
      1
    • tau^- &rarr e^- anti_nu_e nu_tau [+ gamma]
    • tau^+ &rarr e^+ nu_e anti_nu_tau [+ gamma]
      2
    • tau^- &rarr mu^- anti_nu_mu nu_tau [+ gamma]
    • tau^+ &rarr mu^+ nu_mu anti_nu_tau [+ gamma]
      3
    • tau^- &rarr pi^- nu_tau
    • tau^+ &rarr pi^+ anti_nu_tau
      4
    • tau^- &rarr pi^- pi^0 nu_tau
    • tau^+ &rarr pi^+ pi^0 anti_nu_tau
      5
    • tau^- &rarr pi^- pi^0 pi^0 nu_tau
    • tau^+ &rarr pi^+ pi^0 pi^0 anti_nu_tau

    • tau^- &rarr pi^- pi^- pi^+ nu_tau
    • tau^+ &rarr pi^+ pi^+ pi^- anti_nu_tau
    6
  • tau^- &rarr K^- nu_tau
  • tau^+ &rarr K^+ anti_nu_tau
    7
  • tau^- &rarr K^- pi^0 nu_tau
  • tau^+ &rarr K^+ pi^0 anti_nu_tau

  • tau^- &rarr pi^- K_S0 nu_tau
  • tau^+ &rarr pi^+ K_S0 anti_nu_tau

  • tau^- &rarr pi^- K_L0 nu_tau
  • tau^+ &rarr pi^+ K_L0 anti_nu_tau
    8
  • tau^- &rarr pi^- pi^- pi^+ pi^0 nu_tau
  • tau^+ &rarr pi^+ pi^+ pi^- pi^0 anti_nu_tau
    9
  • tau^- &rarr pi^0 pi^0 pi^0 pi^- nu_tau
  • tau^+ &rarr pi^0 pi^0 pi^0 pi^+ anti_nu_tau

    • For other channels spin weight at present will not be calculated. 1.0 will be returned.

    ACKNOWLEDGMENTS:


    The first functional version of this algorithm was created on inspiration and with help from Dimitris Varouchas, Claire Gwenlan, Soshi Tsuno, Andy Buckley, Elzbieta Richter-Was and other members of ATLAS MC group.

    USER INPUT OUTPUT METHODS; FURTHER PARTICIPATION NEEDED:


    We need help from pilot users. In particular methods to read events stored in formats used in experiments MC simulations need to be prepared.

    Last update: 19 November 2012