Undergrad Metrics and conformal transformations

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Conformal field theory involves complex concepts, particularly conformal transformations, which require understanding how metrics transform. The transformation condition $$\Lambda (x) g_{\mu \nu} = g_{\rho \sigma} \frac {\partial x'^\rho}{\partial x^\mu} \frac {\partial x'^\sigma}{\partial x^\nu}$$ is crucial for deriving the relationship between different coordinate systems. A query arises regarding the use of the metric $$g_{\mu \nu}$$ in the original coordinates to lower indices of $$dx'^\mu$$ from a different coordinate system. Clarification is sought on whether this approach is valid given the transformation laws. Understanding these transformations is essential for grasping the underlying principles of conformal field theory.
FuzzySphere
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Conformal field theory is way over my head at the moment, but I decided to "dip my toes into it," and I watched a little video talking about conformal transformations. Now, I know that in a conformal transformation, $$x^\mu \to x'^\mu ,$$ the metric must satisfy $$\Lambda (x) g_{\mu \nu} = g_{\rho \sigma} \frac {\partial x'^\rho}{\partial x^\mu} \frac {\partial x'^\sigma}{\partial x^\nu}.$$ From this I have been informed that we can derive the condition $$dx'^\mu dx'_\mu = \Lambda (x) dx^\mu dx_\mu .$$ I have tried using the condition on the metric to derive this, only to get to this condition: $$g_{\mu \nu} dx'^\mu dx'^\nu = \Lambda g_{\mu \nu} dx^\mu dx ^\nu ,$$ but I have one query: can we use the metric $$g_{\mu \nu}$$ in the $$x^\mu$$ coordinates to lower the indices of $$dx'^\mu ,$$ seeing as they are from a different coordinate system?
 
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FuzzySphere said:
the metric must satisfy Λ(x)gμν=gρσ∂x′ρ∂xμ∂x′σ∂xν.
I observe ' and without ' are upside down.
\Lambda g_{\mu\nu}=g'_{\mu\nu}=g_{\rho\sigma} \ (\partial x^{\rho}/\partial x'^{\mu}) \ ( \partial x^{\sigma}/ \partial x'^{\nu})
 
anuttarasammyak said:
I observe ' and without ' are upside down.
\Lambda g_{\mu\nu}=g'_{\mu\nu}=g_{\rho\sigma} \ (\partial x^{\rho}/\partial x'^{\mu}) \ ( \partial x^{\sigma}/ \partial x'^{\nu})
No, that is the transformation law for the metric, what I have is the coordinate representation of the pull back of the metric by the conformal transformation.
 
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