# Tagged Questions

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### Wick's theorem for calculating OPE

I am trying to understand a calculation using Wick's theorem. Let $T(z)$ be the analytic part of a stress-energy tensor, and $\phi(z)$ a free boson field. Now, ...
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### The basic equation of bosonization

[..quoting from Page 11 of Polchinski Vol2..] Given $1+1$ conformal bosonic fields $H(z)$ one has their OPE as, $H(z)H(0) \sim -ln(z)$ Then from here how do the following identities come? ...
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I have a s****d question, how to calculate the central charge of $bc$ conformal-field theory in Polchinski's string theory, Eq. (2.5.12)? For a $bc$ CFT given by $$S=\frac{1}{2\pi } \int d^2 z \,\,b ... 2answers 117 views ### Identity of Operator Product Expansion (OPE) I have one more s****d question in Polchinski's string theory book, Eqs. (2.3.14a)$$ j^{\mu}(z) :e^{ik \cdot X(0,0)}:~ \sim~ \frac{k^{\mu}}{2 z} :e^{ik \cdot X(0,0)}:,$$where j^{\mu}_a ... 1answer 130 views ### Virasoro TT OPE in Polchinski's book I'm trying to understand eq. 2.2.11 in Polchinski's first book. He's computing$$:\partial X^\mu(z)\partial X_\mu(z): :\partial' X^\nu(z')\partial' X_\nu(z'):$$Now, I understand why this ... 0answers 97 views ### Explicit evaluation of a radially ordered product I am trying to understand the application of the operator product expansion to calculate the radially ordered product in the complex plain of T_{zz}(z)\partial_w X^{\rho}(w) which should result in ... 1answer 1k views ### Why/How is this Wick's theorem? Let \phi be a scalar field and then I see the following expression for the square of the normal ordered version of \phi^2(x).$$T(:\phi^2(x)::\phi^2(0):) ~=~ 2<0|T(\phi(x)\phi(0))|0>^2  ...
I don't understand how to calculate this generalized two-point function or propagator, used in some advanced topics in quantum field theory, a normal ordered product (denoted between $::$) is ...