期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：5
页码：2268-2274
DOI：10.1073/pnas.1909872117
出版社：The National Academy of Sciences of the United States of America
摘要：We apply to the random-field Ising model at zero temperature ( T = 0 ) the perturbative loop expansion around the Bethe solution. A comparison with the standard ϵ expansion is made, highlighting the key differences that make the expansion around the Bethe solution much more appropriate to correctly describe strongly disordered systems, especially those controlled by a T = 0 renormalization group (RG) fixed point. The latter loop expansion produces an effective theory with cubic vertices. We compute the one-loop corrections due to cubic vertices, finding additional terms that are absent in the ϵ expansion. However, these additional terms are subdominant with respect to the standard, supersymmetric ones; therefore, dimensional reduction is still valid at this order of the loop expansion.
关键词：disordered systems ; critical exponents ; perturbative expansion ; Bethe lattices ; Ising model
