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arXiv 1905.05850gr-qc
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在QCD相变中由径迹异常产生的原初标量引力波

Primordial scalar gravitational waves produced at the QCD phase transition due to the trace anomaly

De-Chang Dai, Dejan Stojkovic

摘要:

仅依靠基本粒子和引力的标准模型,我们研究了起源于量子物理学的一个新的引力波源的细节。也就是说,众所周知,弯曲背景中的无质量场会遭受所谓的“迹异常”。这种反常可以用新的标量自由度来解释,这种自由度考虑了量子物质在引力场中的宏观效应。这些场的线性有效作用量描述了标量(与横向相反)引力波,这在爱因斯坦的理论中是不存在的。由于这些新的自由度直接耦合到QCD中的规范场标量,早期宇宙中的QCD相变时期可能是原初宇宙引力辐射的一个来源。虽然在QCD密度下(温度比u和d夸克质量高得多),异常很可能完全不受抑制,但为了小心,我们引入了窗函数,它切断了异常效应可能被抑制的非常低的频率。然后我们计算了今天经过适当调整的引力波信号的特征应变。没有窗函数的参数空间区域给出了更强的信号,并且应变和频率都落在不久的将来的引力波实验(例如LISA和大爆炸观察者)的灵敏度范围内。即使在原则上,人们也可以用引力波天文学来研究量子物理的可能性是令人兴奋的,并且对该领域的未来努力具有价值。

英文摘要:

Relying only on the standard model of elementary particles and gravity, we study the details of a new source of gravitational waves whose origin is in quantum physics. Namely, it is well known that massless fields in curved backgrounds suffer from the so-called "trace anomaly". This anomaly can be cast in terms of new scalar degrees of freedom which take account of macroscopic effects of quantum matter in gravitational fields. The linearized effective action for these fields describes scalar (as opposed to transverse) gravitational waves, which are absent in Einstein's theory. Since these new degrees of freedom couple directly to the gauge field scalars in QCD, the epoch of the QCD phase transition in early universe is a possible source of primordial cosmological gravitational radiation. While the anomaly is most likely fully unsuppressed at the QCD densities (temperature is much higher than the u and d quark masses), just to be careful we introduced the window function which cuts-off very low frequencies where the anomaly effect might be suppressed. We then calculated the characteristic strain of the properly adjusted gravitational waves signal today. The region of the parameter space with no window function gives a stronger signal, and both the strain and the frequencies fall within the sensitivity of the near future gravitational wave experiments (e.g. LISA and The Big Bang Observer). The possibility that one can study quantum physics with gravitational wave astronomy even in principle is exciting, and will be of value for future endeavors in this field.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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