There are different models which are based on the gauge symmetry <svg style="vertical-align:-3.24037pt;width:180.66251px;" id="M2" height="14.725" version="1.1" viewBox="0 0 180.66251 14.725" width="180.66251" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,14.725)"> <g transform="translate(72,-60.22)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑆</tspan> <tspan style="font-size: 12.50px; " x="8.1269503" y="0">𝑈</tspan> <tspan style="font-size: 12.50px; " x="18.304392" y="0">(</tspan> <tspan style="font-size: 12.50px; " x="22.467892" y="0">3</tspan> <tspan style="font-size: 12.50px; " x="28.719391" y="0">)</tspan> </text> <text transform="matrix(1,0,0,-1,-39.05,60.37)"> <tspan style="font-size: 8.75px; " x="0" y="0">𝐶</tspan> </text> <text transform="matrix(1,0,0,-1,-29.21,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">⊗</tspan> <tspan style="font-size: 12.50px; " x="13.303192" y="0">𝑆</tspan> <tspan style="font-size: 12.50px; " x="21.430141" y="0">𝑈</tspan> <tspan style="font-size: 12.50px; " x="31.620087" y="0">(</tspan> <tspan style="font-size: 12.50px; " x="35.783585" y="0">3</tspan> <tspan style="font-size: 12.50px; " x="42.035088" y="0">)</tspan> </text> <text transform="matrix(1,0,0,-1,17,60.37)"> <tspan style="font-size: 8.75px; " x="0" y="0">𝐿</tspan> </text> <text transform="matrix(1,0,0,-1,26.47,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">⊗</tspan> <tspan style="font-size: 12.50px; " x="13.303192" y="0">𝑈</tspan> <tspan style="font-size: 12.50px; " x="23.493137" y="0">(</tspan> <tspan style="font-size: 12.50px; " x="27.656635" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="33.908134" y="0">)</tspan> </text> <text transform="matrix(1,0,0,-1,64.54,60.37)"> <tspan style="font-size: 8.75px; " x="0" y="0">𝑋</tspan> </text> </g> </g> </svg> (331), and some of them include exotic particles, and others are constructed without any exotic charges assigned to the fermionic spectrum. Each model build-up on 331 symmetry has its own interesting properties according to the representations of the gauge group used for the fermionic spectrum, that is, the main reason to explore and identify the possible sources of flavor changing neutral currents and lepton flavor violation at tree level.