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Gauge/gravity duality: an overview Z. Bajnok

Gauge/gravity duality: an overview Z. Bajnok

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CFT: Integrablity + Bethe Ansatz<br />

Mixing matrix on the subspace Tr [ Z i1 . . . Z iJ<br />

]<br />

of dim 2 J : Minah<strong>an</strong>-Zarembo 2002<br />

∆ = H 0 + λH 1 + λ 2 H 2 + . . . = J I +<br />

λ<br />

8π 2H XXX + λ 2 H 2 + . . .<br />

H 2 : next-to-nearest neighbour integrable! → use Bethe <strong>an</strong>satz<br />

1. choose a groundstate: Z = Z 1 → Tr [ Z J] = Tr [ZZZZZ . . . ZZZZ] ↔| ↑ . . . ↑〉<br />

2. excitations Z...ZXZ...X with SUSY multiplet X = Z 2 , Z 3 , Ψ α a, Ψa, ˙α D µ<br />

n<br />

{ }} {<br />

3. pl<strong>an</strong>e wave: ∑ n e ipn Tr( Z...Z XZ . . . ZZ)<br />

4. scattering states: ∑ n 1 n 2 a 1 a 2<br />

e ip 1n 1 +ip 2 n 2 Tr( Z...Z } {{ } X a1 Z...Z X a2 Z . . . Z)+S(12) b 1b 2<br />

n 1<br />

n 2<br />

{ }} {<br />

symmetry completely fixes the S-matrix for <strong>an</strong>y λ (satisfies unitarity, crossing, Y<strong>an</strong>g-Baxter)<br />

Bethe <strong>an</strong>satz follows from S-matrix: Shastry’s Hubbard S-matrix<br />

a 1 a 2<br />

∑<br />

12

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