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arXiv 1006.3756hep-phastro-ph.SR
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扩散超新星中微子背景集体味振荡的可观测性

On the Observability of Collective Flavor Oscillations in Diffuse Supernova Neutrino Background

Sovan Chakraborty, Sandhya Choubey, Kamales Kar

摘要:

集体味振荡已知会在超新星(SN)中微子和反中微子光谱中产生多重分裂。这些光谱分裂不仅取决于中微子的质量等级,而且还取决于初始的相对通量组成。对未来银河系超新星信号中光谱分裂的观测有望揭示中微子的质量等级模式。然而,由于扩散超新星中微子背景(DSNB)由所有过去超新星的中微子通量叠加而成,并且由于不同的超新星预计具有略微不同的初始通量,因此检查集体振荡的等级依赖签名是否可以在通量谱的平均化中幸存下来是相关的。由于中微子和反中微子的初始相对通量谱的SN的实际分布是未知的,我们假设它们的对数正态分布。我们研究了层次灵敏度对对数正态分布函数的均值和方差的依赖性。我们发现,层次的敏感性依赖于相对初始亮度的平均值至关重要。宽度的作用是降低所有平均初始相对光度值的层次敏感性。我们发现,在非常小的混合角($θ_{13}$)的限制,只考虑统计误差,即使是非常温和的值的方差,几乎没有可检测的层次的灵敏度,如果平均相对光度的$ν_e$和$\barν_e$大于1。

英文摘要:

Collective flavor oscillations are known to bring multiple splits in the supernova (SN) neutrino and antineutrino spectra. These spectral splits depend not only on the mass hierarchy of the neutrinos but also on the initial relative flux composition. Observation of spectral splits in a future galactic supernova signal is expected to throw light on the mass hierarchy pattern of the neutrinos. However, since the Diffuse Supernova Neutrino Background (DSNB) comprises of a superposition of neutrino fluxes from all past supernovae, and since different supernovae are expected to have slightly different initial fluxes, it is pertinent to check if the hierarchy dependent signature of collective oscillations can survive this averaging of the flux spectra. Since the actual distribution of SN with initial relative flux spectra of the neutrinos and antineutrinos is unknown, we assume a log-normal distribution for them. We study the dependence of the hierarchy sensitivity to the mean and variance of the log-normal distribution function. We find that the hierarchy sensitivity depends crucially on the mean value of the relative initial luminosity. The effect of the width is to reduce the hierarchy sensitivity for all values of the mean initial relative luminosity. We find that in the very small mixing angle ($θ_{13}$) limit considering only statistical errors even for very moderate values of variance, there is almost no detectable hierarchy sensitivity if the mean relative luminosities of $ν_e$ and $\barν_e$ are greater than 1.

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