# Sign confusions on CFT (yellow book) Page 29

1. Oct 24, 2012

### ivantheczar

On the book Conformal Field Theory by Francesco, Mathieu and Senechal (the yellow book), in the derivation of the propagator kernel $K(\delta t,\xi,\xi')$ on (2.73), the signs on the first and second line just doesn't match.

On first line it has $-\xi^+ T \xi'-{\xi'}^+ T \xi'$ while the second line, after simplifying, has $\xi^+ T \xi'-{\xi'}^+ T \xi'$, which is necessary to identify the term with the derivatives.

However, tracing back up to the definition of the properties of the coherent states, I cannot find any way to fix this sign. Does any one has encounter this part and have a solution?

(For those without the book, the page is attached)

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2. Oct 25, 2012

### Hypersphere

It is not mentioned in the errata (for future reference, it is found at http://www.physique.usherbrooke.ca/pages/senechal/cft ), however I wonder if there really should be a negative sign in the exponent in eq. (2.69c). I don't have time to check it carefully now, but compare, for example, Fradkin's notes: http://webusers.physics.illinois.edu/~efradkin/phys582/582-chapter8.pdf [Broken]

Last edited by a moderator: May 6, 2017