“School of Particles And Accelerator”

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Paper   IPM / Particles And Accelerator / 14317
School of Particles and Accelerator
  Title:   Hadron energy spectrum in polarized top-quark decays considering the effects of hadron and bottom quark masses
1.  S. Mohammad Moosavi Nejad
2.  M Balali
  Status:   Published
  Journal: Eur. Phys. J. C
  No.:  3
  Vol.:  76
  Year:  2016
  Pages:   173
  Supported by:  IPM
We present the analytical expressions for the next-to-leading order corrections to the partial decay width t(↑) → bW+, followed by b → H_bX, for nonzero b-quark mass (mb≠0) in the fixed-flavor-number scheme (FFNs). To make the predictions for the energy distribution of outgoing hadrons H_b, as a function of the normalized H_b-energy fraction xH, we apply the general-mass variable-flavor-number scheme (GM-VFNs) in a specific helicity coordinate system where the polarization of top quark is evaluated relative to the b-quark momentum. We also study the effects of gluon fragmentation and finite hadron mass on the hadron energy spectrum so that hadron masses are responsible for the low-xH threshold. In order to describe both the b-quark and the gluon hadronizations in top decays we apply realistic and nonperturbative fragmentation functions extracted through a global fit to e+e− annihilation data from CERN LEP1 and SLAC SLC by relying on their universality and scaling violations.

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