SEMILEPTONIC DECAY IN THE LEPTOPHOBIC Z MODEL

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SEMILEPTONIC DECAY IN THE
LEPTOPHOBIC Z MODEL
BERIN B.
SIRVANLI Gazi University TROIA07
International Conference on Hadron Physics
30 August 3 September 2007 Çanakkale - Türkiye
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OUTLINE

• Leptophobic Z Model
• Matrix Elements for the
  Decay
• Numerical Analysis
• Conclusion

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1- LEPTOPHOBIC Z MODEL

• Z gauge bosons are proposed some models in
  the SM extension . These are
• E6-Model
• LR-Symmetric models
• Extra Dimensions
• 3-3-1 Model etc.

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• The extra neutral gauge boson can be leptophobic
  by introducing the kinetic mixing term in the E6-
  model.
• In the leptophobic model, U(1) charge is zero
  for all the ordinary left and right handed lepton
  fields within the SM. However, 27 representation
  of E6 contain new right handed neutrino which is
  absent in SM.
• In Grand Unification Theory of view, a U(1)
  gauge group remains as a low energy effective
  theory after the symmetry breaking of the E6
  group. We assume that the E6 group is broken
  through the following breaking chain,
• E6 ---gt SO(10) ? U(1)?
• ---gt SU(5) ? U(1)? ? U(1)?
• ---gt SU(2)L ? U(1)Y ? U(1)
• where U(1) is a linear combination of two
  additional gauge group, U(1)? and U(1)?.
• U(1) gauge group charge is Q Q? cos? - Q?
  sin?.
• ? is the E6 (?-type) mixing
  angle(?tan-1(3/5)-1 37o) .

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• The interaction Lagrangian of fermion fields
  and Z gauge boson can be written as
• where the ratio of gauge couplings
  ,
• gQ and gY is the gauge couplings respectively ,
  U(1) and U(1).
• The general fermion Z
  couplings depend on two free parameters, tan? and
  ?.

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The Z gauge boson can be leptophobic when
for lepton doublet L, and
right-handed singlet ec (Lepton fields in E6
models)The Z boson can be made leptophobic
with
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2 - MATRIX ELEMENTS FOR THE
DECAY

• The decay at quark
  level is described by
• transition. In the SM, effective Hamiltonian
  responsible for the
• transition is given by
• The effective Hamiltonian describing
  transition can be written as
• where

Hadronic Part
Leptonic Part
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For the decay amplitude of the
decay in the leptophobic Z we have,

• where
  
• Seklinde verilir.

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• For the form factors are given as follows,
• A1 (f1 - g1) , A2 (f2 g2)
• B1 (f1 g1) , B2 (f2 g2)
• (T.M.Aliev,M.Savci /hep-ph/0510133).

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• We write the ? baryon spin(1/2) four vector in
  terms of a unit vector along the ? baryon spin
  in its rest frame,
• And we choose the unit vectors along
  longitudinal, transverse and normal components of
  the ? polarization as

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Differential decay rate
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To analysis the asymmetry parameter

• When ? is unpolarized, (??0)
• When ?b is unpolarized, (??b0)

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3- Numerical Analysis

• The value of input parameters
• Z mass limits are between
  

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The dependence of the differential decay
branching ratio as function of the momentum
transfer
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Total branching ratio as function of the
effective coupling constant in the leptophobic Z
model
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The dependence of the longitudinal polarization
for the decay
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The dependence of the normal polarization for the
decay
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• The transverse component PT of the ??
  polarization,
• There is no interference terms between SM and
  Leptophobic Z model contributions and terms
  proportional to Usb involves to the BR and
  polarization effects. Therefore it can not induce
  CP violation.

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The distribution of asymmetry
parameter as a function of momentum transfer .
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• 4- CONCLUSION
• We have analysed the longitudinal,transverse and
  normal polarization of ? baryon on q2 dependence.
• The dependence of the branching ratio on
• is investigated and the dependence of the
  polarization parameter of ?b baryon on q2
  dependence is also investigated.
• ?b asymmetry parameter hasnt been measured yet.
  However, it can be measured in the LHC. It is a
  good tool for investigate to new physics and make
  test of the theoretical models.

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• THANK YOU!