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arXiv 1209.3030hep-thgr-qcquant-ph
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宇宙弦时空中平坦边界引起的费米真空极化

Fermionic vacuum polarization by a flat boundary in cosmic string spacetime

E. R. Bezerra de Mello, A. A. Saharian, S. V. Abajyan

摘要:

本文研究了宇宙弦时空中由平边界诱导的大质量费米子场的费米子凝聚和能量动量张量的重整化真空期望值。在此分析中,我们假设场算子在边界上服从MIT袋边界条件。我们明确地将VEVs分解为边界自由和边界诱导部分。这两个部分都提供了通用公式,它们对与宇宙弦相关的任何参数值都有效。对于无质量场,费米子凝聚体中的无边界部分和能量动量张量中的边界诱导部分消失。对于有质量的场,径向应力等于无边界部分和边界诱导部分的能量密度。沿宇宙弦轴的边界诱导应力部分消失了。总的能量密度处处为负,而沿方位角方向的有效压力在边界附近为正,在宇宙弦附近为负。我们表明,对于远离边界的点,边界诱导的部分在费米子凝聚和VEV的能量动量张量消失的字符串。

英文摘要:

In this paper we investigate the fermionic condensate and the renormalized vacuum expectation value (VEV) of the energy-momentum tensor for a massive fermionic field induced by a flat boundary in the cosmic string spacetime. In this analysis we assume that the field operator obeys MIT bag boundary condition on the boundary. We explicitly decompose the VEVs into the boundary-free and boundary-induced parts. General formulas are provided for both parts which are valid for any value of the parameter associated with the cosmic string. For a massless field, the boundary-free part in the fermionic condensate and the boundary-induced part in the energy-momentum tensor vanish. For a massive field the radial stress is equal to the energy density for both boundary-free and boundary-induced parts. The boundary-induced part in the stress along the axis of the cosmic string vanishes. The total energy density is negative everywhere, whereas the effective pressure along the azimuthal direction is positive near the boundary and negative near the cosmic string. We show that for points away from the boundary, the boundary-induced parts in the fermionic condensate and in the VEV of the energy-momentum tensor vanish on the string.

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