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arXiv 0802.0970cond-mat.str-elcond-mat.stat-mech
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具有二次能量色散和长程相互作用的Luttinger液体的动态结构因子

Dynamic structure factor of Luttinger liquids with quadratic energy dispersion and long-range interactions

Peyman Pirooznia, Florian Schuetz, Peter Kopietz

摘要:

本文计算了具有二次能量色散k^2/2 m和长程密度-密度相互作用的一维无自旋费米子的动力学结构因子S(Ω,q),其傅里叶变换f_q由小动量转移q << q_0 << k_F决定.这里q_0是动量转移截止,k_F是费米动量。利用泛函玻色化和对称化闭费米子环的已知性质,得到了小参数q_0 /kF下的逆不可约极化的二阶展开式.与基于传统玻色化的微扰理论相比,我们的泛函玻色化方法不受质量壳层奇异性的困扰。对于可展开为f_q = f_0 + f_0^{2} q^2/2 + O(q^4)且f_0^{2}有限的相互作用,我们证明了动量标度q_c = 1/|m f_0^{2}|分离了两种状态,其特征在于集体零声模式的宽度gamma_q的不同q依赖性和S(ω,q)的其他特征。当q_c << q << k_F时,我们发现在这个区域中的线形是非洛仑兹的,其总宽度为q^3/(mq_c),并且在下边缘处具有阈值奇异性。

英文摘要:

We calculate the dynamic structure factor S (omega, q) of spinless fermions in one dimension with quadratic energy dispersion k^2/2m and long range density-density interaction whose Fourier transform f_q is dominated by small momentum-transfers q << q_0 << k_F. Here q_0 is a momentum-transfer cutoff and k_F is the Fermi momentum. Using functional bosonization and the known properties of symmetrized closed fermion loops, we obtain an expansion of the inverse irreducible polarization to second order in the small parameter q_0 / k_F. In contrast to perturbation theory based on conventional bosonization, our functional bosonization approach is not plagued by mass-shell singularities. For interactions which can be expanded as f_q = f_0 + f_0^{2} q^2/2 + O (q^4) with finite f_0^{2} we show that the momentum scale q_c = 1/ | m f_0^{2} | separates two regimes characterized by a different q-dependence of the width gamma_q of the collective zero sound mode and other features of S (omega, q). For q_c << q << k_F we find that the line-shape in this regime is non-Lorentzian with an overall width gamma_q of order q^3/(m q_c) and a threshold singularity at the lower edge.

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