arXiv subjects

M. Worek

Publications and source records attributed to M. Worek.

43 records · Page 3Linked to original sources

arXiv2004

Transverse spin effects in H/A -> tau^+ tau^- ; tau^{+-} -> nu X^{+-}, Monte Carlo approach

The transverse spin effects may be helpful to distinguish between scalar (J^{PC}=0^{++}) or pseudoscalar (J^{PC}=0^{-+}) nature of the spin zero (Higgs) particle once discovered in future accelerator experiments. The correlations can manifest themselves e.g. in distribution of acollinearity angle of X^{+-} in decay chain H/A -> tau^+ tau^- ; tau^{+-} -> nu X^{+-}. This delicate measurement will require however reconstruction of the Higgs boson rest-frame. Then, questions of the combined detector-theoretical effects may be critical to establish reliability of the method. Appropriate Monte Carlo program is essential. In the present paper we extend the standard universal interface, of the TAUOLA tau-lepton decay library, to include the complete spin effects for tau leptons originating from the spin zero particle. As usual, the interface is expected to work with any Monte Carlo generator providing Higgs boson production, and subsequent decay into pair of tau leptons. Some example of numerical results and cross checks of the program, will be also given.

hep-ph↗

arXiv2004

Probing the CP nature of the Higgs boson at linear colliders with tau spin correlations; the case of mixed scalar--pseudoscalar couplings

The prospects for the measurement of the pseudoscalar admixture in the h-tau-tau coupling to a Standard Model Higgs boson of 120 GeV mass are discussed in a quantitative manner e+ e- collisions of 350 GeV centre-of-mass energy. Specific angular distributions in the h --> tau tau; tau --> rho nu decay chain can be used to probe mixing angles of scalar--pseudoscalar h-tau-tau couplings. In the discussion of the feasibility of the method, assumptions on the properties of a future detector for an e+ e- linear collider such as TESLA are used. The Standard Model Higgsstrahlung production process is taken as an example. For the expected performance of a typical Linear Collider set-up, the sensitivity of a measurement of the scalar--pseudoscalar mixing angle turned out to be 6 degree. It will be straightforward to apply our results to estimate the sensitivity of a measurement, in cases another scenario of the Higgs boson sector (Standard Model or not) is chosen by nature. The experimental error of the method is expected to be limited by the statistics.

hep-ph↗

arXiv2003

The tauola-photos-F environment for the TAUOLA and PHOTOS packages, release II

We present the system for versioning two packages: the TAUOLA of tau-lepton decay and PHOTOS for radiative corrections in decays. The following features can be chosen in an automatic or semi-automatic way: (1) format of the common block HEPEVT; (2) version of the physics input (for TAUOLA): as published, as initialized by the CLEO collaboration, as initialized by the ALEPH collaboration (it is suggested to use this version only with the help of the collaboration advice), new optional parametrizations of matrix elements in 4-pi decay channels; (3) type of application: stand-alone, universal interface based on the information stored in the HEPEVT common block including longitudinal spin effects in the elementary Z/gamma* -> tau+ tau- process, extended version of the standard universal interface including full spin effects in the H/A -> tau+ tau- decay, interface for KKMC Monte Carlo, (4) random number generators; (5) compiler options.

hep-ph↗

arXiv2003

Measuring the Higgs boson parity at a Linear Collider using the tau impact parameter and tau --> rho nu decay

We demonstrate that a measurement of the impact parameter in one-prong tau decay can be useful for the determination of the Higgs boson parity in the H/A --> tau tau; tau --> rho nu decay chain. We have estimated that for a detection set-up such as TESLA, use of the information from the tau impact parameter can improve the significance of the measurement of the parity of the Standard Model 120 GeV Higgs boson to 4.5 sigma, and in general by factor of about 1.5 with respect to the method where this information is not used. We also show that the variation in the assumption on the precision of the measurement of the impact parameter and/or pi's momenta does not affect the sensitivity of the method. This is because the method remains limited by the type of twofold ambiguity in reconstructing the tau momentum.

hep-ph↗

arXiv2002

Measuring the Higgs boson's parity using tau --> rho nu

We present a very promising method for a measurement of the Higgs boson parity using the H/A -> tau^+ tau^- --> rho^+ nu rho^- nu --> pi^+ pi^0 nu pi^- pi^0 nu decay chain. The method is both model independent and independent of the Higgs production mechanism. Angular distributions of the tau decay products which are sensitive to the Higgs boson parity are defined and are found to be measurable using typical properties of a future detector for an e^+ e^- linear collider. The prospects for the measurement of the parity of a Higgs boson with a mass of 120 GeV are quantified for the case of e^+ e^- collisons of 500 GeV center of mass energy with an integrated luminosity of 500 fb^-1. The Standard Model Higgsstrahlung production process is used as an example.

hep-ph↗

arXiv2002

Novosibirsk hadronic currents for tau -> 4pi channels of tau decay library TAUOLA

The new parameterization of form factors developed for 4pi channels of the tau lepton decay and based on Novosibirsk data on e^+e^- -> 4pi has been coded in a form suitable for the TAUOLA Monte Carlo package. Comparison with results from TAUOLA using another parameterization, i.e. the CLEO version of 1998 is also included.

hep-ph↗

arXiv2001

Spin effects in tau-lepton pair production at LHC

Question of the proper incorporation of spin effects in tau lepton decays is often of importance. In present work, case of the Z/gamma to tau+ tau- production mechanism is studied in detail. As an example, the effects due to the spin correlations on the potential for the Minimal Supersymmetric Standard Model (MSSM) Higgs searches in the tau tau decay channel at the Large Hadron Collider (LHC) are discussed. For these processes, the Standard Model Z/gamma to tau tau -pair production is a dominant background. The spin effects in high energy physics reactions, can be implemented up to certain approximation, independently of the algorithm and matrix elements used by the production program. Information stored on every generated event can be sufficient. The algorithm based on such approximation is documented. Question of the theoretical uncertaintity is discussed only partly.

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