The lF4 and sine-Gordon Field Equation
•The simplest examples are:
•J = lF4  which leads to the cubic KG equation:
• ¶m¶mF + m2F +lF3 = 0
•And  JsG = (sin lF) m2/l-m2 F
•which leads to the sine-Gordon equation:
•
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When l approaches  zero they both reduce to the  usual linear KG equation: ¶m¶m+m2f=0