Dynamics of baryons from string theory and vector dominance
Dynamics of baryons from string theory and vector dominance
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DOI：
10.1088/1126-6708/2007/09/063
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发表时间：
2007-05
影响因子：
5.4
通讯作者：
D. Hong;M. Rho;Ho-Ung Yee;Piljin Yi
中科院分区：
文献类型：
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作者：
D. Hong;M. Rho;Ho-Ung Yee;Piljin Yi
我们从弦论的角度考虑QCD的全息模型，并研究重子。在这个模型中，介子被统一地表示为一个五维U（NF）= U（1）× SU（NF）杨-米尔斯场，重子被经典地表示为具有单位庞特里亚金数和Nc个电荷的SU（NF）孤子。孤子被证明是非常小的大的t Hooft耦合限制，使我们能够引入一个有效的字段。它与介子的耦合由孤子结构决定，包括与SU（NF）场强度的直接磁耦合以及与U（NF）规范场的最小耦合。在降维后，这种有效作用量以与大Nc展开一致的方式再现了核子与无限介子塔之间的所有相互作用项。我们进一步发现，所有的电磁相互作用，通过全息处方从相同的有效作用推断，是由矢量介子的无限塔介导的，使重子电磁形状因子完全矢量主导。我们估计了核子-介子耦合和反常磁矩，与自然界比较。
We consider a holographic model of QCD from string theory, a la Sakai and Sugimoto, and study baryons. In this model, mesons are collectively realized as a five-dimensional U(NF) = U(1) × SU(NF) Yang-Mills field and baryons are classically identified as SU(NF) solitons with a unit Pontryagin number and Nc electric charges. The soliton is shown to be very small in the large 't Hooft coupling limit, allowing us to introduce an effective field . Its coupling to the mesons are dictated by the soliton structure, and consists of a direct magnetic coupling to the SU(NF) field strength as well as a minimal coupling to the U(NF) gauge field. Upon the dimensional reduction, this effective action reproduces all interaction terms between nucleons and an infinite tower of mesons in a manner consistent with the large Nc expansion. We further find that all electromagnetic interactions, as inferred from the same effective action via a holographic prescription, are mediated by an infinite tower of vector mesons, rendering the baryon electromagnetic form factors completely vector-dominated as well. We estimate nucleon-meson couplings and also the anomalous magnetic moments, which compare well with nature.