Exploring Polyakov's Action: Diffeomorphism Symmetry?

In summary, the Polyakov action S describes the dynamics of a string in a target space and has two local symmetries, diffeomorphism on the world sheet and Weyl invariance. The target space metric G_{ij}(X) transforms under diffeomorphism on the target space as G_{ij}(X)\to G_{ij}^\prime(X^\prime)=\frac{\partial X^k}{\partial X^i}\frac{\partial X^l}{\partial X^j}G_{kl}(X). The handling of the term \partial_\alpha X^i\partial_\beta X^j can be done using the chain rule.
  • #1
synoe
23
0
The Polyakov action,

[tex]
S=\frac{1}{4\pi\alpha^\prime}\int d^2\sigma\sqrt{-h}h^{\alpha\beta}G_{ij}(X)\partial_\alpha X^i\partial_\beta X^j
[/tex]

has the local symmetries, diffeomorphism on world sheet and the Weyl invariance.
But is diffeomorphism on the target space also a symmetry?
The target space metric transforms

[tex]
G_{ij}(X)\to G_{ij}^\prime(X^\prime)=\frac{\partial X^k}{\partial X^i}\frac{\partial X^l}{\partial X^j}G_{kl}(X).
[/tex]

But I don't know how to deal with the part, [itex]\partial_\alpha X^i\partial_\beta X^j[/itex].
 
Physics news on Phys.org
  • #2
Apply the chain rule as usual, it should work.
 

1. What is Polyakov's action and why is it important in physics?

Polyakov's action is a mathematical expression used in theoretical physics to describe the behavior of strings in space-time. It is important because it helps to explain the fundamental interactions between elementary particles and can provide insights into the nature of the universe.

2. What is the diffeomorphism symmetry and how does it relate to Polyakov's action?

The diffeomorphism symmetry is a mathematical concept that describes the invariance of a system under smooth coordinate transformations. It is relevant to Polyakov's action because the action is invariant under diffeomorphisms, meaning that the equations of motion are unchanged even if the coordinates are transformed.

3. What implications does diffeomorphism symmetry have for our understanding of space-time?

The diffeomorphism symmetry implies that space-time is a flexible and dynamic concept, where the geometry and coordinates can change without affecting the fundamental laws of physics. This challenges our traditional understanding of space-time as a fixed and rigid framework.

4. How does the concept of diffeomorphism symmetry impact string theory?

In string theory, the concept of diffeomorphism symmetry is essential as it allows for the consistent formulation of the theory. This symmetry ensures that the equations of motion are valid in any coordinate system, making it a powerful tool for studying the behavior of strings in a wide range of scenarios.

5. What are some current research areas related to exploring Polyakov's action and diffeomorphism symmetry?

Some current research areas include using diffeomorphism symmetry to study higher-dimensional string theories, investigating its role in holography and black hole thermodynamics, and exploring its applications in other areas of physics such as condensed matter systems and quantum gravity.

Similar threads

  • Beyond the Standard Models
Replies
1
Views
988
  • Beyond the Standard Models
Replies
1
Views
1K
  • Beyond the Standard Models
Replies
4
Views
3K
  • Beyond the Standard Models
Replies
1
Views
1K
  • Beyond the Standard Models
Replies
1
Views
1K
  • Special and General Relativity
Replies
4
Views
598
  • Beyond the Standard Models
Replies
2
Views
2K
  • Beyond the Standard Models
Replies
7
Views
1K
  • Beyond the Standard Models
Replies
1
Views
1K
  • Advanced Physics Homework Help
Replies
1
Views
1K
Back
Top