标题： 一维系统中连续对称性下的长程关联 显示英文标题

标题： Infinite-range correlations in 1D systems with continuous symmetry

摘要： O(N)对称的格点标量场被考虑，与化学势和源项耦合。 以N=2为例，表明这样的系统甚至在(0+1)维情况下，当化学势取某些离散值时，也能产生长程相关性和非零的真空期望值。 讨论了后者现象产生的不同机制，这取决于源项是否设置为零或非零值。 在结论中，这些发现与Mermin-Wagner定理的关系被提及。 显示英文摘要

摘要： O(N)-symmetric lattice scalar fields are considered, coupled to a chemical potential and source terms. At the example of N=2, it is shown that such systems can even in (0+1) dimensions produce infinite-range correlations and a non-zero vacuum expectation value whenever the chemical potential assumes certain discrete values. Different mechanisms for how the latter phenomena are produced are discussed, depending on whether source terms are set to zero or non-zero values. In the conclusion, the relation of these findings to the Mermin-Wagner theorem is addressed.