12.07.2015 Views

Ivancevic_Applied-Diff-Geom

Ivancevic_Applied-Diff-Geom

Ivancevic_Applied-Diff-Geom

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

1154 <strong>Applied</strong> <strong>Diff</strong>erential <strong>Geom</strong>etry: A Modern Introductionwe can see by a direct calculation that the end points of the string becomenoncommutative⎧⎨ iθ ij , (σ = σ ′ = 0)[X i (τ, σ), X j (τ, σ ′ )] = −iθ ij , (σ = σ ′ = π)⎩0, (otherwise).On the other hand, it is noted that the conjugate momenta have the modeexpansion identical with that in the Neumann case:P i (τ, σ) = 12πα ′ (g ij∂ τ − 2πα ′ B ij ∂ σ )X j (τ, σ)= 1 π p i + 1π √ ∑e −inτ cos(nσ)α n,i .2α ′Note that the relations (6.247) and (6.248) are in the same form as aT–duality transformation, although the correspondence is a formal sense,because we are not considering any compactification of space–time. Thegeneralized T–duality transformation, namely O(D, D)−transformation, isdefined byn≠0E ′ = (aE + b)(cE + d) −1 , (6.251)with a, b, c and d being D ׄD«real matrices. (D is the dimension ofa bspace–time.) The matrix h = is O(D, D) matrix, which satisfiesc dh T Jh = J, where J =( ) 0 1D.1 D 0The relations (6.247) and (6.248) correspond to the case of the inversiona = d = 0, b = c = 1 D .6.5.9.3 Construction of Overlap VerticesHere we construct Witten’s open string theory in the constant B−fieldbackground by obtaining the explicit formulas of the overlap vertices. As isunderstood from the fact that the action of the ghosts (6.239) contains nobackground fields, the ghost sector is not affected by turning on the B−fieldbackground. Thus we may consider the coordinate sector only. First, let us

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!