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arXiv 0903.5495hep-ph
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从含介质规范玻色子传播子的Schwinger-Dyson方程看强耦合等离子体中准费米子的消失

Disappearance of quasi-fermions in the strongly coupled plasma from the Schwinger-Dyson equation with in-medium gauge boson propagator

Masayasu Harada, Shunji Yoshimoto

摘要:

我们非微扰地研究了手征对称位相中的费米子谱,着重研究了规范玻色子的介质内修正效应。费米子谱是通过求解Schwinger-Dyson方程(ψ)在实时间轴上用阶梯近似得到的。结果表明,与树型玻色子传播子相比,规范玻色子的介质内效应使费米子谱函数的峰值展宽。随着规范耦合值的增加,峰值变得更宽。这种加宽是由费米子和规范玻色子的多次散射引起的,这些散射是通过非微扰的重新计算引起的。特别是规范玻色子传播子的朗道阻尼在展宽中起着重要的作用。结果表明,在强耦合区没有明显的峰,这意味着强耦合等离子体中准费米子的消失。这表明在强耦合QGP中准粒子图像可能不再成立。

英文摘要:

We non-perturbatively study the fermion spectrum in the chiral symmetric phase focusing on the effects of in-medium corrections for gauge boson. The fermion spectrum is derived by solving the Schwinger-Dyson equation (SDE) with ladder approximation on the real time axis. It is shown that the peak of the fermion spectral function is broadened by in-medium effects for gauge boson compared with the peak obtained with the tree gauge boson propagator. The peak becomes much broader as the value of the gauge coupling increases. This broadening is caused by multiple scatterings of fermions and gauge bosons included through the non-perturbative resummation done by the SDE. In particular, the Landau damping of gauge boson propagator plays an important role in the broadening. Our results show no clear peak in the strong coupling region, implying the disappearance of quasi-fermions in the strongly coupled plasma. This indicates that quasi-particle picture may be no longer valid in the strongly coupled QGP.

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