We consider the algebraic couplings in the tree level effective action of the heterotic string. We show how these couplings can be computed from closed string field theory. When the light fields we are interested in are charged under an underlying N $$ \mathcal{N} $$ = 2 R-charge in the left-moving sector, their quartic effective potential localizes at the boundary of the worldsheet moduli space, in complete analogy to the previously studied open string case. In particular we are able to compute the quartic closed string field theory potential without resorting to any explicit expression for the 3- and the 4-strings vertices but only using the L ∞ relations between them. As a non trivial example we show how the heterotic Yang-Mills quartic potential arises in this way.

中文翻译：

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异性弦场理论中有效作用的定位

我们考虑异质串的树级有效作用中的代数耦合。我们展示了如何从闭弦场理论计算这些耦合。当我们感兴趣的光场在左移扇区中的潜在 N $$ \mathcal{N} $$ = 2 R-charge 下充电时，它们的四次有效势定位在世界表模空间的边界处，在与之前研究的开放字符串案例完全类似。特别是，我们能够计算四次闭弦场论势，而无需对 3 弦和 4 弦顶点使用任何明确的表达式，而仅使用它们之间的 L ∞ 关系。作为一个非平凡的例子，我们展示了异质性 Yang-Mills 四次势是如何以这种方式产生的。