Classifying bions in Grassmann sigma models and non-Abelian gauge theories by D-branes
Classifying bions in Grassmann sigma models and non-Abelian gauge theories by D-branes
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DOI：
10.1093/ptep/ptv009
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发表时间：
2014-09
影响因子：
3.5
通讯作者：
T. Misumi;M. Nitta;N. Sakai
中科院分区：
文献类型：
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作者：
T. Misumi;M. Nitta;N. Sakai
我们在具有扭曲边界条件的 R 1 × S 1 上对 Grassmann GrNF,NC sigma 模型（包括 CP NF−1 模型）中的生物进行分类。我们将这些模型表述为 UNCgauge 理论，在基本表示中带有 NF 风格。这些理论可以推广为超对称规范理论，并且进一步可以嵌入到 II 型超弦理论中的 D 膜构型中。我们重点关注由多个分数瞬时子组成的特定配置，称为中性生物离子和带电生物离子，Unsal 及其合作者将其识别为微扰红外重整子（G. V. Dunne 和 M. Unsal, J. High Energy Phys. 1211, 170 (2012)；G. V. Dunne 和 M. Unsal, Phys. Rev. D 87, 025015 （2013））。我们表明，D 膜构型以及模矩阵提供了一个非常有用的工具来对这些模型中所有可能的生物体构型进行分类。与 CP N F−1 模型相反，存在拓扑电荷大于 1（NC 阶）的 Bogomol'nyi-Prasad-Sommerfield (BPS) 分数瞬子，无法简化为瞬子和分数瞬子的复合。因此，我们发现 Grassmann sigma 模型承认由 BPS 和反 BPS 分数瞬子组成的中性生物粒子，每个瞬子的拓扑电荷大于（小于）一（负一），并且不能分解为瞬子-反瞬子对和其余的。发现 CP N F−1 模型没有带电生物离子。相比之下，我们发现 Grassmann sigma 模型承认带电生物离子，为此我们构造了场方程的精确非 BPS 解。
We classify bions in the Grassmann GrNF,NC sigma model (including the CP NF−1 model) on R 1 × S 1 with twisted boundary conditions. We formulate these models as UNCgauge the- ories with NF flavors in the fundamental representations. These theories can be promoted to supersymmetric gauge theories and, further, can be embedded into D-brane configurations in type-II superstring theories. We focus on specific configurations composed of multiple frac- tional instantons, termed neutral bions and charged bions, which are identified as perturbative infrared renormalons by Unsal and his collaborators (G. V. Dunne and M. Unsal, J. High Energy Phys. 1211, 170 (2012); G. V. Dunne and M. Unsal, Phys. Rev. D 87, 025015 (2013)). We show that D-brane configurations, as well as the moduli matrix, offer a very useful tool to classify all possible bion configurations in these models. In contrast to the CP N F−1 model, there exist Bogomol'nyi-Prasad-Sommerfield (BPS) fractional instantons with topological charges greater than unity (of order NC) that cannot be reduced to a composite of an instanton and fractional instantons. As a consequence, we find that the Grassmann sigma model admits neutral bions made of BPS and anti-BPS fractional instantons, each of which has a topological charge greater (less) than one (minus one), that are not decomposable into an instanton-anti-instanton pair and the rest. The CP N F−1 model is found to have no charged bions. In contrast, we find that the Grassmann sigma model admits charged bions, for which we construct exact non-BPS solutions of the field equations.