Conjecture on the thermodynamic limit of the effective reduced density-matrix series

Let ρN(x,t)\rho_N(x,t) be the finite-volume one-particle reduced density matrix. Let wLL1+1/4w_L\sim L^{1+1/4}, define

BL={nZ:wL<n<wL},BLext=BL{1,,N+1},BLint={1,,N+1},\mathcal{B}_L=\{n\in\mathbb{Z}:-w_L<n<w_L\},\qquad \mathcal{B}_L^{\mathrm{ext}}=\mathcal{B}_L\setminus\{1,\ldots,N+1\},\qquad \mathcal{B}_L^{\mathrm{int}}=\{1,\ldots,N+1\},

and let μpa\mu_{p_a} and μha\mu_{h_a} be the rapidities associated with particle indices paBLextp_a\in\mathcal{B}_L^{\mathrm{ext}} and hole indices haBLinth_a\in\mathcal{B}_L^{\mathrm{int}}. Let D^NG^N;1\widehat D_N\widehat{\mathcal G}_{N;1} and F0F_0 be the functionals and form-factor data appearing in the effective series.

Effective-series thermodynamic-limit conjecture.

limN,L+ρN(x,t)=limN,L+ρN;eff(x,t),\lim_{N,L\to+\infty}\rho_N(x,t)=\lim_{N,L\to+\infty}\rho_{N;\mathrm{eff}}(x,t),

where

ρN;eff(x,t)=n=0N+1p1<<pn\paBLexth1<<hn\haBLinta=1neixu(μha)eixu(μpa)(D^NG^N;1)({pa}1n{ha}1n)[F0({μpa}{μha});ξ;ξF0].\rho_{N;\mathrm{eff}}(x,t)=\sum_{n=0}^{N+1}\sum_{\substack{p_1<\dots<p_n\p_a\in\mathcal{B}_L^{\mathrm{ext}}}}\sum_{\substack{h_1<\dots<h_n\h_a\in\mathcal{B}_L^{\mathrm{int}}}}\prod_{a=1}^{n}\frac{e^{-\mathrm{i}xu(\mu_{h_a})}}{e^{-\mathrm{i}xu(\mu_{p_a})}}\cdot(\widehat D_N\widehat{\mathcal G}_{N;1})\left(\begin{array}{c}\{p_a\}_{1}^{n}\\\{h_a\}_{1}^{n}\end{array}\right)\left[F_0\left(*\left|\begin{array}{c}\{\mu_{p_a}\}\\\{\mu_{h_a}\}\end{array}\right.\right);\xi;\xi_{F_0}\right].

Here the star denotes the running variable of F0F_0 on which the two functionals act.

The conjecture formalizes the approximation obtained by restricting excitation integers, dropping the stated finite-volume remainders, and replacing the oscillating exponent by its thermodynamic limit. The supplied text does not establish the equality, so its resolution remains open.

Sources & referencesView supporting material

Primary source

K. K. Kozlowski, “Asymptotic analysis and quantum integrable models”, arXiv:1508.06085 (2015).

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