Mass dimension of a scalar field in two dimensions?

In summary, the mass dimension of a scalar field in 2 dimensions is 0. This can be seen by imposing that the action has dimension 0 and using the dimensions of the other terms in the action. However, when writing the action for a superfield, there can be difficulties with the dimensions of certain terms, such as the quadratic term which must have dimension 0. This can be resolved by using the kinetic term with derivatives, as shown in Green, Schwarz, and Witten's book. There may also be issues with the dimensions in two dimensions, where theta has two components and the components are real. Further clarification may be needed in this case.
  • #1
alialice
51
0
Which is the mass dimension of a scalar filed in 2 dimensions?
In 4 dim I know that a scalar field has mass dimension 1, by imposing that the action has dim 0:
[itex]S=\int d^4 x \partial_{\mu} A \partial^{\mu} A [/itex]
where
[itex]\left[S\right]=0[/itex]
[itex]\left[d^4 x \right] =-4[/itex]
[itex]\left[ \partial_{\mu} \right]=1[/itex]
[itex]\Rightarrow \left[A\right]=1[/itex]
Doing the same in 2 dim I found
[itex]\left[A\right]=0[/itex]
Is it right?
I need it for a model in supersymmetry.
 
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  • #2
Yes, that's right, if you stick to the same action.
 
  • #3
Ok thanks!
But now I have a problem in writing the action of the superfield
[itex] \phi =A +i \bar{\theta} \psi + \frac{i}{2}\bar{\theta} \theta F [/itex]
Phi has the same mass dimension of A, 0 in two dimension.
In the kinetic part of the action, there must be a quadratic term, such as [itex] \phi \bar{\phi} [/itex], which would have mass dimension zero. But the invariants
[itex] \int d^2 x d\theta [/itex] and [itex] \int d^2 x d^2 \theta [/itex]
need after them something of dimension 3/2 or 1 respectively, assumed that the dimension of [itex] d\theta [/itex] is 1/2 .
How can I resolve this?
 
  • #4
That quadratic term you mention doesn't seem to be a kinetic term; for that you need derivatives. See e.g. chapter 4.1 of Green,Schwarz,Witten (vol.1).
 
  • #5
haushofer said:
That quadratic term you mention doesn't seem to be a kinetic term; for that you need derivatives. See e.g. chapter 4.1 of Green,Schwarz,Witten (vol.1).

I'm studying on Paul West's book and at page 112 he says that [itex]\bar{\phi}\phi[/itex] is the kinetic term because if you resolve the integral in theta you find the kinetic action for the component of the superfield.
I'd like to do the same thing in two dimension: writing down the action of the superfield with the kinetic term, the term with the mass and the cubic interaction term. Only in the case of cubic phi I have to resolve the integral over theta.
But my problem is the dimensions as I've just said... So I don't know what to do! Maybe I'm doing some errors?
In two dimensions theta has two components, and I don't have used the chiral formalism; in addition the components are real.
In the superfield phi, which I wrote in a my previous post, appear both theta and bar theta.
Do you have an idea of what to do? Thank you!
 

Related to Mass dimension of a scalar field in two dimensions?

1. What is the mass dimension of a scalar field in two dimensions?

The mass dimension of a scalar field in two dimensions is given by the number of mass units, which is equivalent to the number of powers of mass in the field's Lagrangian. In two dimensions, the mass dimension is typically denoted as [M].

2. How does the mass dimension of a scalar field affect its behavior in two dimensions?

The mass dimension of a scalar field is directly related to its scaling behavior. In two dimensions, a scalar field with a mass dimension of [M] will scale as [M]^(2-d), where d is the number of dimensions. This means that the field will have different properties and interactions compared to fields with different mass dimensions.

3. Can the mass dimension of a scalar field in two dimensions be negative?

Yes, the mass dimension of a scalar field in two dimensions can be negative. This occurs when the field has a negative mass term in its Lagrangian, resulting in a negative power of mass in the dimension. Negative mass dimensions can also arise in theories with non-standard dimensions, such as fractional dimensions.

4. How is the mass dimension of a scalar field related to its renormalization?

The mass dimension of a scalar field is an important factor in its renormalization. In two dimensions, fields with different mass dimensions will have different scaling behaviors, which can affect the renormalizability of the theory. In general, a field with a lower mass dimension will be easier to renormalize than a field with a higher mass dimension.

5. Does the mass dimension of a scalar field change in different dimensions?

Yes, the mass dimension of a scalar field can change in different dimensions. In general, the mass dimension of a field in d dimensions is given by [M]^(d-2), meaning that the mass dimension will increase as the number of dimensions increases. This can have significant implications for the behavior and interactions of the field in different dimensions.

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