math phi z phi r math bare field renormalised field constant determined lagrangian density becomes math mathcal l frac partial mu phi r partial mu phi r frac r phi r frac lambda r phi r frac delta z partial mu phi r partial mu phi r frac delta phi r frac delta lambda phi r math experimentally measurable renormalised mass coupling constant respectively math delta z z quad delta z r quad delta lambda lambda z lambda r math constants determined first three terms lagrangian density written terms renormalised quantities
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