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arXiv 0907.5003astro-ph.COhep-ph
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在中性子暗物质方案中大质量引力子的核合成约束

Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

Richard H. Cyburt, John Ellis, Brian D. Fields, Feng Luo, Keith A. Olive, Vassilis C. Spanos

摘要:

在大爆炸核合成(BBN)过程中或之后,大质量引力伴子衰变为中性伴子暗物质粒子和标准模型,这可能会改变原始轻元素丰度。在这里,我们提出了一套新的代码的细节,用于评估这种影响,包括一个新的治疗的基础上PYTHIA的强子衰变的大规模,不稳定的粒子,如引力子引起的阵雨的演变。我们还开发了一个分析处理的非热强子在早期宇宙中的传播,并使用此轻元素的生产,进而对衰变粒子的寿命和丰度的分析估计。然后,我们考虑具体的情况下,不稳定的大质量引力子的约束最小超对称扩展的标准模型(CMSSM)。我们目前的上限,其可能的原始丰度衰变前的不同可能的引力子质量,与CMSSM参数沿带最轻的中性子提供所有的天体物理冷暗物质密度。我们没有发现任何CMSSM解决方案的宇宙学Li 7问题的小m_{3/2}。不考虑这一点,对于m_{1/2} ~ 500 GeV和tan β = 10,其他轻元素丰度强加了上限m_{3/2} n_{3/2} /n_γ< 3 \times 10^{-12} GeV到< 2 \times 10^{-13} GeV,对于m_{3/2} = 250 GeV到1 TeV,这在共湮灭和聚焦点带中都是类似的,并且对于tan β = 50稍微弱一些,特别是对于较大的m_{1/2}。对于较大的m_{3/2},这种约束一般也会减弱,对于m_{3/2} > 3 TeV,我们发现m_{3/2} n_{3/2} /n_γ的范围很窄,其值随m_{3/2}的增加而增加,其中Li 7的丰度与其他轻元素的丰度勉强相容。

英文摘要:

The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical cold dark matter density. We do not find any CMSSM solution to the cosmological Li7 problem for small m_{3/2}. Discounting this, for m_{1/2} ~ 500 GeV and tan beta = 10 the other light-element abundances impose an upper limit m_{3/2} n_{3/2}/n_γ< 3 \times 10^{-12} GeV to < 2 \times 10^{-13} GeV for m_{3/2} = 250 GeV to 1 TeV, which is similar in both the coannihilation and focus-point strips and somewhat weaker for tan beta = 50, particularly for larger m_{1/2}. The constraints also weaken in general for larger m_{3/2}, and for m_{3/2} > 3 TeV we find a narrow range of m_{3/2} n_{3/2}/n_γ, at values which increase with m_{3/2}, where the Li7 abundance is marginally compatible with the other light-element abundances.

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