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arXiv 1101.2402hep-th
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截断BPS理论中的Skyrmions

Skyrmions in a truncated BPS theory

Paul Sutcliffe

摘要:

最近的研究表明,(4 + 1)维Yang-Mills理论可以写成一个(3 + 1)维BPS Skyrme模型,其中Skyrme场耦合到一个无限大的矢量介子塔上。将这座塔截断为一个单一的矢量介子,得到了标准Skyrme模型的扩展,即π介子与ρ介子耦合的理论,其中显著的简化是没有引入额外的自由参数。本文讨论这种截断理论,并给出了重子数为1~4的Skyrmions的结果。该方法涉及到使用的Atiyah-Manton建设,其中Skyrme场近似的杨米尔斯瞬子的holonomy的扩展版本。结果发现,耦合到ρ介子显着降低Skyrmion结合能,产生一个改进的比较与核的实验数据。一个截断,包括一个矢量和一个轴矢量介子也进行了研究,提供了一个模型的π介子,ρ介子和α 1介子。结合能因包含这个额外的介子而进一步降低,使Skyrmion能量更接近原子核的能量。通过将重子4号Skyrmion的能量等同于He-4的质量来固定能量单位,得到的所有较低重子数的质量都在实验值的20 MeV以内,这是一个比标准Skyrme模型小四倍的误差。

英文摘要:

Recently, it has been shown that (4+1)-dimensional Yang-Mills theory may be written as a (3+1)-dimensional BPS Skyrme model, in which the Skyrme field is coupled to an infinite tower of vector mesons. Truncating this tower to a single vector meson yields an extension of the standard Skyrme model to a theory of pions coupled to the rho meson, with the significant simplification that no additional free parameters are introduced. The present paper is concerned with this truncated theory and results are presented for Skyrmions with baryon numbers one to four. The approach involves the use of an extended version of the Atiyah-Manton construction, in which the Skyrme field is approximated by the holonomy of a Yang-Mills instanton. It is found that the coupling to the rho meson significantly reduces Skyrmion binding energies, to produce an improved comparison with the experimental data on nuclei. A truncation that includes both a vector and an axial vector meson is also investigated, providing a model of pions, the rho meson and the a1 meson. Binding energies are further reduced by the inclusion of this additional meson, shifting the Skyrmion energies a little closer to those of nuclei. Fixing the energy unit by equating the energy of the baryon number four Skyrmion to the He-4 mass, yields masses for all lower baryon numbers that are within 20 MeV of the experimental values, which is an error that is four times smaller than in the standard Skyrme model.

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