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arXiv 2009.06274math.AG
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带点光滑曲线上主丛的通用模栈的Picard群 II

The Picard group of the universal moduli stack of principal bundles on pointed smooth curves II

Roberto Fringuelli, Filippo Viviani

AI总结:

本文研究了代数闭域上约化群$G$的通用模栈$\mathrm{Bun}_{G,g,n}$的Picard群,给出了新的函子表示,确定了刚化后的Picard群及相关障碍同态的像,并以此计算出半稳定$G$-丛模空间的除子类群。

摘要:

本文是arXiv:2002.07494的续篇。对于代数闭域$k$上的任意约化群$G$,我们研究了亏格为$g$的$n$点光滑射影曲线上$G$-丛的通用模栈$\mathrm{Bun}_{G,g,n}$的Picard群。具体而言:我们给出了$\mathrm{Bun}_{G,g,n}$的Picard群的新函子表示;我们研究了限制同态,将其映射到固定光滑曲线上主$G$-丛的模栈的Picard群;我们确定了$\mathrm{Bun}_{G,g,n}$通过$G$的中心进行刚化后的Picard群,以及相关gerbe的障碍同态的像。作为推论,我们计算了亏格为$g$的$n$点光滑射影曲线上半稳定$G$-丛的模空间的除子类群。

英文摘要:

In this paper, which is a sequel of arXiv:2002.07494, we investigate, for any reductive group $G$ over an algebraically closed field $k$, the Picard group of the universal moduli stack $\mathrm{Bun}_{G,g,n}$ of $G$-bundles over $n$-pointed smooth projective curves of genus $g$. In particular: we give new functorial presentations of the Picard group of $\mathrm{Bun}_{G,g,n}$; we study the restriction homomorphism onto the Picard group of the moduli stack of principal $G$-bundles over a fixed smooth curve; we determine the Picard group of the rigidification of $\mathrm{Bun}_{G,g,n}$ by the center of $G$ as well as the image of the obstruction homomorphism of the associated gerbe. As a consequence, we compute the divisor class group of the moduli space of semistable $G$-bundles over $n$-pointed smooth projective curves of genus $g$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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