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In physics, the Pati–Salam model is a Grand Unification Theory (GUT) proposed in 1974 by nobel laureate Abdus Salam and Jogesh Pati. The unification is based on there being four quark color charges, dubbed red, green, blue and violet (or lilac), instead of the conventional three, with the new "violet" quark being identified with the leptons. The model also has Left–right symmetry and predicts the existence of a high energy right handed weak interaction with heavy W' and Z' bosons. Originally the fourth color was labelled "lilac" to alliterate with "lepton". Pati–Salam is a mainstream theory and a viable alternative to the . It can be embedded within an (as can ). ==Core theory== The Pati–Salam model states that the gauge group is either or and the fermions form three families, each consisting of the representations and . This needs some explanation. The center of is . The in the quotient refers to the two element subgroup generated by the element of the center corresponding to the two element of and the 1 elements of and . This includes the right-handed neutrino, which is now likely believed to exist. See neutrino oscillations. There is also a and/or a scalar field called the Higgs field which acquires a VEV. This results in a spontaneous symmetry breaking from to or from to and also, : : : : : See restricted representation. Of course, calling the representations things like and is purely a physicist's convention, not a mathematician's convention, where representations are either labelled by Young tableaux or Dynkin diagrams with numbers on their vertices, but still, it is standard among GUT theorists. The weak hypercharge, Y, is the sum of the two matrices: :. The last also needs explaining. It corresponds to an automorphism of the (unextended) Pati–Salam group which is the composition of an involutive outer automorphism of which isn't an inner automorphism with interchanging the left and right copies of . This explains the name left and right and is one of the main motivations for originally studying this model. This extra "left-right symmetry" restores the concept of parity which had been shown not to hold at low energy scales for the weak interaction. In this extended model, is an irrep and so is . This is the simplest extension of the minimal left-right model unifying QCD with B−L. Since the homotopy group : this model predicts monopoles. See 't Hooft–Polyakov monopole. This model was invented by Jogesh Pati and Abdus Salam. This model doesn't predict gauge mediated proton decay (unless it is embedded within an even larger GUT group). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pati–Salam model」の詳細全文を読む スポンサード リンク
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