Changes between Version 1 and Version 2 of 331

06/14/17 11:23:27 (3 years ago)



  • 331

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     1= '''The 331 Model''' =
     3==  '''Author''' ==
     4* Dong-Ming Zhang (
     5 * School of Physics, Peking University
     7== '''Model Description''' ==
     8The 331 model is a simple extension of the SM based on the gauge group SU(3)_C x SU(3)_L x U(1)_X.
     9There are different versions of this model which can be characterized by a
     10parameter called beta. Models with different beta have new particles with different electric charges.
     11But in general, they all have the same features.
     12i) Unlike the SM that anomaly cancellation is fulfilled within each generation, the gauge anomaly is cancelled in the 331 model when considering all the generations. In particular, the number of triplets must be equal to the number of anti-triplets in fermion sector, due to the nontrivial SU(3) gauge structure. The number of generations N must be a multiple of three. On the other hand, in order to ensure QCD an asymptotic free theory, the number of generations N has to be smaller than six. So N is equal to three. That explains why the SM has three generations. 
     13ii) One of the three quark generations is different from the
     14other two, making sure that the anomaly is free, which leads to tree-level  Flavour Changing Neutral Current (FCNC) through a new neutral gauge boson Z'. And if we choose the third generation of quark as a different one, the heavy top quark mass may be explained.
     15iii) Peccei-Quinn (PQ) symmetry which can solve the strong CP problem is a natural result of
     16gauge invariance in the 331 model. Thus PQ symmetry does not suffer from quantum corrections, which means it is not a classical symmetry but a quantum-level one.
     17iiii) With the extension of gauge group, particles in the 331 model are richer than the SM.
     19== '''References''' ==
     20* arXiv:1611.09337
     22== '''Model Files''' ==
     24== '''Instructions''' ==