标题： 非零化学势下的U(1) Gross-Neveu 模型 显示英文标题

标题： The U(1) Gross-Neveu Model at Non-Zero Chemical Potential

摘要： 在非零化学势 $\mu$ 下，利用 $1/N_f$ 展开和计算机模拟研究了三维连续手征对称性的四费米子模型。 对于强耦合情况，该模型在零化学势下自发破缺其 U(1) 手征对称性，并通过无质量的派生实现金石机制。 计算机模拟预测了临界化学势 $\mu_c$，接近模型中最轻的费米子质量。 当 $\mu$ 增大超过 $\mu_c$ 时，派生物种的质量迅速从零增加到一个非零值，表明对称性恢复。 得出了一些与非零 $\mu$ 的格点QCD模拟相关的经验教训。 显示英文摘要

摘要： The four-fermi model with continuous chiral symmetry is studied in three dimensions at non-zero chemical potential $\mu$ using both the $1/N_f$ expansion and computer simulations. For strong coupling this model spontaneously breaks its U(1) chiral symmetry at zero chemical potential and the Goldstone mechanism is realized through massless pions. The computer simulation predicts a critical chemical potential $\mu_c$ close to the lightest fermion mass in the model. As $\mu$ is increased beyond $\mu_c$, the pion screening mass increases rapidly from zero to a nonvanishing value indicating symmetry restoration. Some lessons are drawn relevant to lattice QCD simulations at non-zero $\mu$.