TY - JOUR

T1 - Exact four-spinon dynamical correlation function of the Heisenberg model

AU - Abada, A.

AU - Bougourzi, A. H.

AU - Si-Lakhal, B.

N1 - Funding Information:
The work of A.H.B. is supported by the NSF Grant # PHY9309888.

PY - 1997/7/28

Y1 - 1997/7/28

N2 - In this paper we derive the exact expression of the four-spinon contribution to the dynamical correlation function of the spin S = 1/2 anisotropic (XXZ) Heisenberg model in the antiferromagnetic regime. We extensively study its isotropic (XXX) limit and derive perturbatively the Ising one. Our method relies on the quantum affine symmetry of the model, which allows for a systematic diagonalization of the Hamiltonian in the thermodynamic limit and for an exact calculation of matrix elements of local spin operators. In fact, we argue that the familiar criticism of this method related to the complication of these matrix elements is not justified. First, we give, in the form of contour integrals, an exact expression for the n-spinon contribution. After we compile recently found results concerning the two-spinon contribution, we specialize the n-spinon formula to the new case n = 4. Then we give an explicit series representation of this contribution in the isotropic limit. Finally, after we show that this representation is free of divergences, we discuss the Ising limit in which a simple expression is found up to first order in the anisotropy parameter.

AB - In this paper we derive the exact expression of the four-spinon contribution to the dynamical correlation function of the spin S = 1/2 anisotropic (XXZ) Heisenberg model in the antiferromagnetic regime. We extensively study its isotropic (XXX) limit and derive perturbatively the Ising one. Our method relies on the quantum affine symmetry of the model, which allows for a systematic diagonalization of the Hamiltonian in the thermodynamic limit and for an exact calculation of matrix elements of local spin operators. In fact, we argue that the familiar criticism of this method related to the complication of these matrix elements is not justified. First, we give, in the form of contour integrals, an exact expression for the n-spinon contribution. After we compile recently found results concerning the two-spinon contribution, we specialize the n-spinon formula to the new case n = 4. Then we give an explicit series representation of this contribution in the isotropic limit. Finally, after we show that this representation is free of divergences, we discuss the Ising limit in which a simple expression is found up to first order in the anisotropy parameter.

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U2 - 10.1016/S0550-3213(97)00285-X

DO - 10.1016/S0550-3213(97)00285-X

M3 - Article

AN - SCOPUS:0031589473

VL - 497

SP - 733

EP - 753

JO - Nuclear Physics B

JF - Nuclear Physics B

SN - 0550-3213

IS - 3

ER -