Quantum field theory Exercises 6.
2005-12-05
•Exercise 6.1.
Derive the equations of motion for the complex scalar field with the folowing action S=
Z d4x
∂µφ ∂µφ∗−λ
2(φ φ∗−v2)2
.
•Exercise 6.2.
Check explicitly in the model of one scalar field with potentialV(φ) S=
Z d4x
1
2∂µφ ∂µφ−V(φ)
that the energy
E= Z
d3x
1
2φ˙2+1
2∂iφ ∂iφ+V(φ)
is conserved (dE/dt =0) on the equations of motion.
•Exercise 6.3.
Find the dimensions of scalar, spinor, and gauge fields in space-time of dimension d=4.
A useful starting point is the fact that dimension of action S is the dimension of the Plank’s constant, i.e. it is dimensionless in ¯h= 1 units. Repeat the anaysis in arbitrary number of dimensionsd, using actionS=RddxL with usual expressions for LagrangianL.
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